fbpx
Wikipedia

TRS-80

December 31, 2022

This article is about the original TRS-80 (Model I) and its successors (Models III and 4). For an overview of all computers using the TRS-80 and Tandy names, see List of TRS-80 and Tandy-branded computers. For other uses, see TRS-80 (disambiguation).

The TRS-80 Micro Computer System (TRS-80, later renamed the Model I to distinguish it from successors) is a desktop microcomputer launched in 1977 and sold by Tandy Corporation through their Radio Shack stores. The name is an abbreviation of Tandy Radio Shack, Z80 [microprocessor].[4] It is one of the earliest mass-produced and mass-marketed retail home computers.[5]

TRS-80 Model I
TRS-80 Model I with Expansion Interface and display
ManufacturerTandy Corporation
TypeHome computer
Release dateAugust 3, 1977; 45 years ago (1977-08-03)[1]
Lifespan1977–1981, 4 years
Introductory priceUS$599.95 (equivalent to $2,680 in 2021)
DiscontinuedJanuary 1981; 41 years ago (1981-01)
Units sold
  • 100,000+ (as of 1979)[2]
  • 2.4 million (all models)[3]
Operating systemTRSDOS, LDOS, NewDos/80, Level I BASIC
CPUZilog Z80 @ 1.774 MHz
Memory4–48 KB
DisplayMonochrome 12" CRT, 64 × 16 character semigraphics
SoundSquare wave tones

The TRS-80 has a full-stroke QWERTY keyboard, the Zilog Z80 processor, 4 KB dynamic random-access memory (DRAM) standard memory, small size and desk area, floating-point Level I BASIC language interpreter in read-only memory (ROM), 64-character per line video monitor, and a starting price of US$600[1] (equivalent to US$2,700 in 2021). A cassette tape drive for program storage was included in the original package.

While the software environment was stable, the cassette load/save process combined with keyboard bounce issues and a troublesome Expansion Interface contributed to the Model I's reputation as not well-suited to serious use. It lacked support for lowercase characters, which also hampered business adoption.

An extensive line of upgrades and add-on hardware peripherals for the TRS-80 was developed and marketed by Tandy/Radio Shack. The basic system can be expanded with up to 48 KB of RAM (in 16 KB increments), and up to four floppy disk drives and/or hard disk drives. Tandy/Radio Shack provided full-service support including upgrade, repair, and training services in their thousands of stores worldwide.

By 1979, the TRS-80 had the largest selection of software in the microcomputer market.[6] Until 1982, the TRS-80 was the best-selling PC line, outselling the Apple II series by a factor of five according to one analysis.[4]

In mid-1980, the broadly compatible TRS-80 Model III was released. The Model I was discontinued shortly thereafter, primarily due to stricter Federal Communications Commission (FCC) regulations on radio-frequency interference to nearby electronic devices.[7][8] In April 1983, the Model III was succeeded by the compatible TRS-80 Model 4.

Following the original Model I and its compatible descendants, the TRS-80 name became a generic brand used on other unrelated computer lines sold by Tandy, including the TRS-80 Model II, TRS-80 Model 2000, TRS-80 Model 100, TRS-80 Color Computer, and TRS-80 Pocket Computer.

History

Development

 
Tandy/Radio Shack TRS-80 Model I

In the mid-1970s, Tandy Corporation's Radio Shack division was a successful American chain of more than 3,000 electronics stores. Among the Tandy employees who purchased a MITS Altair kit computer was buyer Don French, who began designing his own computer and showed it to vice president of manufacturing John V. Roach, Tandy's former electronic data processing manager.[9][10] Although the design did not impress Roach, the idea of selling a microcomputer did. When the two men visited National Semiconductor in California in mid-1976, Homebrew Computer Club member Steve Leininger's expertise on the SC/MP microprocessor impressed them. National executives refused to provide Leininger's contact information when French and Roach wanted to hire him as a consultant, but they found Leininger working part-time at Byte Shop. Leininger was unhappy at National, his wife wanted a better job, and Texas did not have a state income tax. Hired for his technical and retail experience, Leininger began working with French in June 1976. The company envisioned a kit, but Leininger persuaded the others that because "too many people can't solder", a preassembled computer would be better.[11][12][13][14]

Tandy had 11 million customers that might buy a microcomputer, but it would be much more expensive than the US$30 median price of a Radio Shack product, and a great risk for the very conservative company.[14][13] Executives feared losing money as Sears did with Cartrivision,[15] and many opposed the project; one executive told French, "Don't waste my time—we can't sell computers." As the popularity of CB radio—at one point comprising more than 20% of Radio Shack's sales—declined, however, the company sought new products. In December 1976 French and Leininger received official approval for the project but were told to emphasize cost savings; for example, leaving out lowercase characters saved US$1.50 in components and reduced the retail price by US$5. The original US$199 retail price required manufacturing cost of US$80; the first design had a membrane keyboard and no video monitor. Leininger persuaded Roach and French to include a better keyboard; it, a monitor, datacassette storage, and other features required a higher retail price to provide Tandy's typical profit margin. In February 1977 they showed their prototype, running a simple tax-accounting program, to Charles Tandy, head of Tandy Corporation. The program quickly crashed as the computer's implementation of Tiny BASIC could not handle the US$150,000 figure that Tandy typed in as his salary, and the two men added support for floating-point math to its Level I BASIC to prevent a recurrence. The project was formally approved on 2 February 1977; Tandy revealed that he had already leaked the computer's existence to the press. When first inspecting the prototype, he remarked that even if it did not sell, the project could be worthy if only for the publicity it might generate.[16][13][14]

MITS sold 1,000 Altairs in February 1975, and was selling 10,000 a year. When Charles Tandy asked who would buy the computer, company president Lewis Kornfeld admitted that they did not know if anyone would, but suggested that small businesses and schools might. Knowing that demand was very strong for the US$795 Altair—which cost more than $1,000 with a monitor—Leininger suggested that Radio Shack could sell 50,000 computers,[17][13] but no one else believed him; Roach called the figure "horseshit", as the company had never sold that many of anything at that price. Roach and Kornfeld suggested 1,000 to 3,000 per year; 3,000 was the quantity the company would have to produce to buy the components in bulk. Roach persuaded Tandy to agree to build 3,500—the number of Radio Shack stores—so that each store could use a computer for inventory purposes if they did not sell.[6][11][12][16][13] RCA agreed to supply the video monitor—a black-and-white television with the tuner and speakers removed—after others refused because of Tandy's low initial volume of production. Tandy used the black-and-silver colors of the RCA CRT unit's cabinet for the TRS-80 units also.[13]

Announcement

Having spent less than US$150,000 on development, Radio Shack announced the TRS-80 (Tandy Radio Shack) at a New York City press conference on August 3, 1977.[18] It cost US$399 ($1784 today), or US$599 ($2679 today) with a 12" monitor and a Radio Shack tape recorder; the most expensive product Radio Shack previously sold was a US$500 stereo. The company hoped that the new computer would help Radio Shack sell higher-priced products, and improve its "schlocky" image among customers. Small businesses were the primary target market, followed by educators, then consumers and hobbyists; despite its hobbyist customer base, Radio Shack saw them as "not the mainstream of the business" and "never our large market".[12][19][17][20][21][13]

Although the press conference did not receive much media attention because of a terrorist bombing elsewhere in the city, the computer received much more publicity at Boston University's Personal Computer Fair two days later.[22][21][19][23][24][20][25][26][17][12][6][27][28][excessive citations] A front-page Associated Press article discussed the novelty of a large consumer-electronics company selling a home computer that could "do a payroll for up to 15 people in a small business, teach children mathematics, store your favorite recipes or keep track of an investment portfolio. It can also play cards." Six sacks of mail arrived at Tandy headquarters asking about the computer, over 15,000 people called to purchase a TRS-80—paralyzing the company switchboard—and 250,000 joined the waiting list with a $100 deposit.[12][6][17][24][25][13][excessive citations]

Despite the internal skepticism, Radio Shack aggressively entered the market. The company advertised "The $599 personal computer" as "the most important, useful, exciting, electronic product of our time".[29] Kornfeld stated when announcing the TRS-80, "This device is inevitably in the future of everyone in the civilized world—in some way—now and so far as ahead as one can think", and Tandy's 1977 annual report called the computer "probably the most important product we've ever built in a company factory". Unlike competitor Commodore—which had announced the PET several months earlier but had not yet shipped any—Tandy had its own factories (capable of producing 18,000 computers a month) and distribution network, and even small towns had Radio Shack stores. The company announced plans to be selling by Christmas a range of peripherals and software for the TRS-80, began shipping computers by September, opened its first computer-only store in October, and delivered 5,000 computers to customers by December. Still forecasting 3,000 sales a year, Radio Shack sold over 10,000 TRS-80s in its first one and a half months of sales, 55,000 in its first year, and over 200,000 during the product's lifetime;[25][11][30][12][16][6][21][15][31]: 4 [19][13][excessive citations] one entered the Smithsonian's National Museum of American History.[32] By mid-1978 the waits of two months or more for delivery were over,[33] and the company could state in advertisements that TRS-80 was "on demonstration and available from stock now at every Radio Shack store in this community!"[29]

 
Byte's "1977 trinity": Commodore PET, Apple II, and TRS-80 Model I

Delivery

The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small-businesses. Tandy Corporation's leading position[34] in what Byte magazine called the "1977 Trinity" (Apple Computer, Commodore, and Tandy) had much to do with Tandy's retailing the computer through more than 3,000 of its Radio Shack storefronts in the USA.[35] Tandy claimed it had "7000 [Radio Shack] stores in 40 countries".[36] The pre-release price for the basic system (CPU/keyboard and video monitor) was US$500 and a US$50 deposit was required, with a money-back guarantee at time of delivery.

By 1978, Tandy/Radio Shack promoted itself as "The Biggest Name in Little Computers".[37][36] By 1979 1,600 employees built computers in six factories.[13] Kilobaud Microcomputing estimated in 1980 that Tandy was selling three times as many computers as Apple Computer, with both companies ahead of Commodore.[38] By 1981, InfoWorld described Radio Shack as "the dominant supplier of small computers".[39] Hundreds of small companies produced TRS-80 software and accessories,[40] and Adam Osborne described Tandy as "the number-one microcomputer manufacturer" despite having "so few roots in microcomputing".[41] That year Leininger left his job as director for advanced research; French had left to found a software company,[42] while Roach became Tandy's CEO. Selling computers did not change the company's "schlocky" image; the Radio Shack name embarrassed business customers, and Tandy executives disliked the "Trash-80" nickname for its products. By 1984, computers accounted for 35% of sales, however, and the company had 500 Tandy Radio Shack Computer Centers.[11][16][21][13][43]

Model II and III

By 1979, when Radio Shack launched the business-oriented, and incompatible, TRS-80 Model II, the TRS-80 was officially renamed the TRS-80 Model I to distinguish the two product lines.

After some exhibitors at the 1979 Northeast Computer Show were forced to clarify that their products bearing the TRS-80 name were not affiliated with Radio Shack, publications and advertisers briefly began to use "S-80" generically rather than "TRS-80" under scare of legal action, though this never materialized.[44]

Following the Model III launch in mid-1980, Tandy stated that the Model I was still sold,[45] but it was discontinued by the end of the year. Tandy cited one of the main reasons as being the prohibitive cost of redesigning it to meet stricter FCC regulations covering the significant levels of radio-frequency interference emitted by the original design.[8][7] The Model I radiated so much interference that, while playing games, an AM radio placed next to the computer could be used to provide sounds.[46] Radio Shack offered upgrades (double-density floppy controller, LDOS, memory, reliable keyboard with numeric keypad, lowercase, Level II, RS-232C) as late as 1985.[47]

Hardware

 
Tandy/Radio Shack TRS‑80 Model I PCB
 
Tandy/Radio Shack TRS‑80 Model I Rear Panel Connectors
 
Tandy/Radio Shack TRS‑80 Model I Level II ROM Upgrade PCB

The Model I combines the mainboard and keyboard into one unit, which became a design trend in the 8-bit microcomputer era, although the Model I has a separate power supply unit. It uses a Zilog Z80 processor clocked at 1.78 MHz (later models shipped with a Z80A). The initial Level I machines shipped in late 1977-early 1978 have only 4 KB of RAM. After the Expansion Interface and Level II BASIC were introduced in mid-1978, RAM configurations of 16 KB and up were offered (the first 16 KB was in the Model I itself and the remaining RAM in the Expansion Interface).

The OS ROMs, I/O area, video memory and OS work space occupy the first 16 KB of memory space on the Model I. The remaining 48 KB of the 64 KB memory map space is available for program use, subject to the amount of physical RAM installed. Although the Z80 CPU can use port-based I/O, the Model I's I/O is memory-mapped aside from the cassette tape and RS-232 serial ports.

Keyboard

 
Tandy/Radio Shack TRS‑80 Model I ALPS Keyboard PCB

The TRS-80 Model I keyboard uses mechanical switches that suffer from "keyboard bounce", resulting in multiple letters being typed per keystroke.[48] The problem was described in Wayne Green's editorial in the first issue of 80 Micro.[49] Dirt, cigarette smoke, or other contamination enters the unsealed key switches, causing electrical noise that the computer detects as multiple presses. The key switches can be cleaned, but the bounce recurs when the keyboard is reexposed to the contaminating environment.[50]

Keyboard bounce only occurs in Model I computers with Level II BASIC firmware; Level I BASIC has a "debounce" delay to the keyboard driver to avoid the noisy switch contacts. Tandy's KBFIX utility, the Model III, the last Model I firmware, and most third-party operating systems also implement the software fix, and Tandy changed the keyboard during the Model III's lifetime to an Alps Electric design with sealed switches. The Alps keyboard was available as an upgrade for the Model I for $79.[50]

The keyboard is memory mapped so that certain locations in the processor's memory space correspond to the status of a group of keys.

Video and audio

 
Layout of characters and pixels on the TRS-80 display[51]

The color of the 12" KCS 172 RCA monitor's[13] text is faintly blue (the standard P4 phosphor used in black-and white televisions). Green and amber filters, or replacement tubes to reduce eye fatigue were popular aftermarket items. Later models came with a green-on-black display.

Complaints about the video display quality were common. As Green wrote, "hells bells, [the monitor] is a cheap black and white television set with a bit of conversion for computer use".[49] (The computer could be purchased without the Radio Shack monitor.)[25] CPU access to the screen memory causes visible flicker. The bus arbitration logic blocks video display refresh (video RAM reads) during CPU writes to the VRAM, causing a short black line. This has little effect on normal BASIC programs, but fast programs made with assembly language can be affected. Software authors worked to minimize the effect, and many arcade-style games are available for the Tandy TRS-80.

Because of bandwidth problems in the interface card that replaced the TV's tuner, the display loses horizontal sync if large areas of white are displayed. A simple half-hour hardware fix corrects the problem.

The graphics are displayed at a resolution of 64×16 character positions on a screen measuring 7.5 inches (19 cm) wide and 6.625 inches (16.83 cm) tall.[52] Each character is composed of a 2×3 matrix of pixels, and corresponds to one byte of the 1 KB video memory used by the TRS-80. In each of those bytes, the first six bits control which pixel is displayed. The seventh bit is ignored, and the eighth toggles graphics mode.[51][53] The reason that the seventh bit is ignored is due to the company's decision to have only seven 2102 static RAM chips installed on the computer's motherboard instead of eight to keep the manufacturing cost low.[54] Thus, there are no lowercase letters in the TRS-80 character set of an unmodified Model I, and the number of both graphics symbols and alphanumeric symbols is 64.[55] This can be worked around by deleting the unused bit and piggybacking an eighth 2102 chip onto another.[56] The alphanumeric symbols are displayed in 5×7 matrices of pixels.[51] The 1978 manual for the popular word processor Electric Pencil came with instructions for modifying the computer. Although the modification needs to be disabled for Level II BASIC, its design became the industry standard and was widely sold in kit form,[57] along with an eighth 2102 chip. Later models came with the hardware for the lowercase character set to be displayed with descenders.

With higher-density RAM chips and purpose-built monitors, higher resolution crisp displays are obtainable; 80x24 character displays are available in the Model II, Model 4, and later systems.

The Model I has no built-in speaker. Square wave tones can be produced by outputting data to the cassette port and plugging an amplifier into the cassette "Mic" line. Most games use this ability for sound effects. An adapter was available to use Atari joysticks.[58]

Peripherals

Cassette tape drive

User data was originally stored on cassette tape. Radio Shack's model CTR-41 cassette recorder was included with the US$599 package.[31]: 3–4  The software-based[11] cassette tape interface is slow and erratic;[48] Green described it as "crummy ... drives users up the wall", and the first issue of 80 Micro has three articles on how to improve cassette performance.[49] It is sensitive to audio volume,[25] and the computer gives only a crude indication as to whether the correct volume was set, via a blinking character on screen while data is loaded. To find the correct volume at first use, the load is started and the volume is adjusted until the TRS-80 picked up the data. Then it is halted to rewind the tape and restart the load. Users were instructed to save multiple copies of a software program file, especially if audio tape cassettes instead of certified data tape was used. Automatic gain control or indicator circuits can be constructed to improve the loading process (the owner's manual provides complete circuit diagrams for the whole machine, including the peripheral interfaces, with notes on operation).

An alternative to using tape was data transmissions from the BBC's Chip Shop programme in the UK, which broadcast software for several different microcomputers over the radio. A special program was loaded using the conventional tape interface. Then the radio broadcast was connected to the cassette tape interface. Tandy eventually replaced the CTR-41 unit with the CTR-80 which had built-in AGC circuitry (and no volume control). This helped the situation, but tape operation is still unreliable.

TRS-80 Model I computers with Level I BASIC read and wrote tapes at 250 baud (about 30 bytes per second); Level II BASIC doubles this to 500 baud (about 60 bytes per second). Some programmers wrote machine-language programs that increases the speed to up to 2,000 bits per second without a loss of reliability on their tape recorders. With the Model III and improved electronics in the cassette interface, the standard speed increased to 1,500 baud that works quite reliably on most tape recorders.

For loading and storing data from tape, the CPU creates the sound by switching the output voltage between three states, creating crude sine wave audio.

The first version of the Model I also has a hardware problem that complicated loading programs from cassette recorders. Tandy offered a small board which was installed at a service center to correct the issue. The ROMs in later models were modified to correct this.

Model I Expansion Interface

Only the Model I uses an Expansion Interface; all later models have everything integrated in the same housing.

The TRS-80 does not use the S-100 bus like other early 8080 and Z80-based computers.[12] A proprietary Expansion Interface (E/I) box, which fits under the video monitor and served as its base, was offered instead. Standard features of the E/I are a floppy disk controller, Centronics parallel port for a printer, and added cassette connector. Optionally, an extra 16 or 32 KB of RAM can be installed and a daughterboard with an RS-232 port.[59] The 40-conductor expansion connector passes through to a card edge connector, which permits the addition of external peripherals such as an outboard hard disk drive, a voice synthesizer, or a VOXBOX voice recognition unit.[60][61]

Originally, printing with the Model I requires the Expansion Interface, but later Tandy made an alternative parallel printer interface available.

The Model I Expansion Interface is the most troublesome part of the TRS-80 Model I system. It went through several revisions. The E/I connects to the CPU/keyboard with a 6-inch ribbon cable which is unshielded against RF interference and its card edge connector tends to oxidize due to its base metal contacts. This demands periodic cleaning with a pencil eraser in order to avoid spontaneous reboots, which contributes to its "Trash-80" sobriquet. Aftermarket connectors plated with gold solves this problem permanently. Software developers also responded by devising a recovery method which became a standard feature of many commercial programs. They accept an "asterisk parameter", an asterisk (star) character typed following the program name when the program is run from the TRSDOS Ready prompt. When used following a spontaneous reboot (or an accidental reset, program crash, or exit to TRSDOS without saving data to disk), the program loads without initializing its data area(s), preserving any program data still present from the pre-reboot session. Thus, for example, if a VisiCalc user suffers a spontaneous reboot, to recover data the user enters V+C+SPACE+✶ at TRSDOS Ready, and Visicalc restores the previous computing session intact.[note 1]

The power button on the E/I is difficult to operate as it is recessed so as to guard against the user accidentally hitting it and turning it off while in use. A pencil eraser or similar object is used to depress the power button and the E/I has no power LED, making it difficult to determine if it is running or not.

The expansion unit requires a second power supply, identical to the base unit power supply. An interior recess holds both supplies.

The user is instructed to power on and power off all peripherals in proper order to avoid corrupting data or potentially damaging hardware components. The manuals for the TRS-80 advise turning on the monitor first, then any peripherals attached to the E/I (if multiple disk drives are attached, the last drive on the chain is to be powered on first and work down from there), the E/I, and the computer last. When powering down, the computer is to be turned off first, followed by the monitor, E/I, and peripherals. In addition, users are instructed to remove all disks from the drives during power up or down (or else leave the drive door open to disengage the read/write head from the disk). This is because a transient electrical surge from the drive's read/write head would create a magnetic pulse that could corrupt data. This was a common problem on many early floppy drives.

The E/I displays a screen full of garbage characters on power up and unless a bootable system disk is present in Drive 0, it hangs there until the user either presses RESET on the back of the computer, which causes it to attempt to boot the disk again, or Break+Reset was pressed, which drops the computer into BASIC. Due to the above-mentioned problems with potentially corrupting disks, it is recommended to power up to the garbage screen with the disk drives empty, insert a system disk, and then hit RESET.

InfoWorld compared the cable spaghetti connecting the TRS-80 Model I's various components to the snakes in Raiders of the Lost Ark.[48] Radio Shack offered a "TRS-80 System Desk"[62] that concealed nearly all the cabling. It can accommodate the complete computer system plus up to four floppy drives and the Quick Printer. Since the cable connecting the Expansion Interface carries the system bus, it is short (about 6 inches). The user has no choice but to place the E/I directly behind the computer with the monitor on top. This causes problems for a non-Tandy monitor whose case did not fit the mounting holes. Also, the friction fit of the edge connector on the already short interconnect cable makes it possible to disconnect the system bus from the CPU if either unit is bumped during operation.

Floppy disk drives

Radio Shack introduced floppy drives in July 1978, about six months after the Model I went on sale. The Model I disk operating system TRSDOS was written by Randy Cook under license from Radio Shack; Randy claimed to have been paid $3000 for it. The first version released to the public was a buggy v2.0. This was quickly replaced by v2.1.[63] Floppy disk operation requires buying the Expansion Interface, which included a single-density floppy disk interface (with a formatted capacity of 85K) based on the Western Digital 1771 single-density floppy disk controller chip. The industry standard Shugart Associates SA-400 minifloppy disk drive was used. Four floppy drives can be daisy-chained to the Model I. The last drive in the chain is supposed to have a termination resistor installed but often it is not needed as it is integrated into later cables.[64]

Demand for Model I drives greatly exceeded supply at first.[49] The drive is unreliable, partly since the interface lacked an external data separator (buffer).[48] The early version(s) of TRSDOS are also buggy, and not helped by the Western Digital FD1771 chip that cannot reliably report its status for several instruction cycles after it receives a command. A common method of handling the delay was to issue a command to the 1771, perform several "NOP" instructions, then query the 1771 for the result. Early TRSDOS neglects the required yet undocumented wait period, and thus false status often returns to the OS, generating random errors and crashes. Once the 1771 delay was implemented, it is fairly reliable.

In 1981, Steve Ciarcia published in Byte the design for a homemade, improved expansion interface with more RAM and a disk controller for the TRS-80.[65]

A data separator and a double-density disk controller (based on the WD 1791 chip) were made by Percom (a Texas peripheral vendor), LNW, Tandy, and others. The Percom Doubler adds the ability to boot and use double density floppies using a Percom-modified TRSDOS called DoubleDOS. The LNDoubler adds the ability to read and write 5+1⁄4-inch (130 mm) diskette drives with up to 720 KB of storage, and also the older 8-inch (200 mm) diskettes with up to 1,155 KB. Near the end of the Model I's lifespan in 1982, upgrades were offered to replace its original controller with a double-density one.

The first disk drives offered on the Model I were Shugart SA-400s which supported 35 tracks and was the sole 5+1⁄4-inch drive on the market in 1977–78. By 1979, other manufacturers began offering drives. Models 3/4/4P uses Tandon TM-100 40-track drives. The combination of 40 tracks and double density gives a capacity of 180 kilobytes per single-sided floppy disk. The use of index-sync means that a "flippy disk" requires a second index hole and write-enable notch. One could purchase factory-made "flippies". Some software publishers formatted one side for Apple systems and the other for the TRS-80.

The usual method of connecting floppy drives involves setting the drive letter via jumper blocks on the drive controller board, but Tandy opted for a slightly more user-friendly technique where all four select pins on the drives are jumpered and the ribbon cable is missing the Drive Select line. Thus, the user does not need to worry about moving jumpers around depending on which position on the chain a drive was in.

A standard flat floppy ribbon cable is usable on the Model I, in which case the drives is jumpered to their number on the chain, or even an IBM PC "twist" cable, which requires setting each drive number to 1, but only permits two drives on the chain.

Although third-party DOSes allow the user to define virtually any floppy format wanted, the "lowest common denominator" format for TRS-80s is the baseline single-density, single-sided, 35-40 track format of the Model I.

Third-party vendors like Aerocomp made available double-sided and 80 track 5+1⁄4-inch and later 3+1⁄2-inch floppy drives with up to 720 KB of storage each. These new drives are half-height and therefore require different or modified drive housings.

Exatron Stringy Floppy

An alternative to cassette tape and floppy disk storage from Exatron sold over 4,000 units by 1981. The device is a continuous loop tape drive, dubbed the stringy floppy or ESF. It requires no Expansion Interface, plugging directly into the TRS-80's 40-pin expansion bus, is much less expensive than a floppy drive, can read and write random-access data like a floppy drive unlike a cassette tape, and it transfers data at up to 14,400 baud. Exatron tape cartridges store over 64 KB of data. The ESF can coexist with the TRS-80 data cassette drive. Exatron also made a complementary RAM expansion board that installed in the TRS-80 keyboard to increase memory to 48 KB without the EI.[66]

Hard drive

Radio Shack introduced a 5 MB external hard disk for the TRS-80 Model III/4 in 1983. It is the same hard disk unit offered for the Model II line, but came with OS software for Model III/4. An adapter is required to connect it to the Model I's E/I.[67] The unit is about the same size as a modern desktop computer enclosure. Up to four hard disks can be daisychained for 20 MB of storage. The LDOS operating system by Logical Systems was bundled, which provides utilities for managing the storage space and flexible backup. The initial retail price for the first (primary) unit (US$2,495 (equivalent to $6,800 in 2021)). Later, a 15MB hard disk was offered in a white case, which can be daisychained for up to 60 MB. Like most hard disks used on 8-bit machines, there is no provision for subdirectories, but the DiskDISK utility is a useful alternative that creates virtual hard disk ".DSK" files that can be mounted as another disk drive, and used like a subdirectory would. To display the directory/contents of an unmounted DiskDISK virtual disk file, a shareware DDIR "Virtual Disk Directory Utility"[68] program was commonly used.

Printers

The "Quick Printer" [69] is an electrostatic rotary printer that scans the video memory through the bus connector, and prints an image of the screen onto aluminum-coated paper in about one second. However, it is incompatible with both the final, buffered version of the Expansion Interface, and with the "heartbeat" interrupt used for the real-time clock under Disk BASIC. This can be overcome by using special cabling, and by doing a "dummy" write to the cassette port while triggering the printer.

Two third-party printers were for 57 mm (2.2 in) metal-coated paper, selling for approximately DM 600 in Germany, and a dot-matrix printer built by Centronics for normal paper, costing at first DM 3000, later sold at approximately DM 1500 in some stores. It has only 7 pins, so letters with descenders such as lowercase "g" do not reach under the baseline, but are elevated within the normal line.

Radio Shack offered an extensive line of printers for the TRS-80 family, ranging from basic 9-pin dot matrix units to large wide-carriage line printers for professional use, daisy-wheel printers, ink jet printers, laser printers and color plotters. All have a Centronics-standard interface and after the introduction of the Color Computer in 1980, many also had a connector for the CoCo's serial interface.

FP-215 is a flatbed plotter.[70]

Software

BASIC

Three versions of the BASIC programming language were produced for the Model I. Level I BASIC fits in 4 KB of ROM, and Level II BASIC fits into 12 KB of ROM. Level I is single precision only and had a smaller set of commands. Level II introduced double precision floating point support and has a much wider set of commands. Level II was further enhanced when a disk system was added, allowing for the loading of Disk BASIC.[12]

Level I BASIC is based on Li-Chen Wang's free Tiny BASIC with more functions added by Radio Shack.[15] The accompanying User's Manual for Level 1 by David A. Lien presents lessons on programming with text and cartoons. Lien wrote that it was "written specifically for people who don't know anything about computers ... I want you to have fun with your computer! I don't want you to be afraid of it, because there is nothing to fear".[71][25] Reviewers praised the manual's quality.[12][72][73] Level I BASIC has only two string variables (A$ and B$), 26 numeric variables (A – Z), and one array, A(). Code for functions like SIN(), COS() and TAN() is not included in ROM but printed at the end of the book. The only error messages are "WHAT?" for syntax errors, "HOW?" for arithmetic errors such as division by zero, and "SORRY" for out of memory errors.

Level I BASIC is not tokenized; reserved words are stored literally. In order to maximize the code that fits into 4 KB of memory, users can enter abbreviations for reserved words. For example, writing "P." instead of "PRINT" saves 3 bytes.

Level II BASIC, introduced in mid-1978, was licensed from Microsoft and is required to use the expansion bus and disk drives. Radio Shack always intended for Level I BASIC to be a stopgap until Level II was ready, and the first brochure for the Model I in January 1978 mentioned that Level II BASIC was "coming soon". It is an abridged version of the 16K Extended BASIC, since the Model I has 12 KB of ROM space. According to Bill Gates, "It was a sort of intermediate between 8K BASIC and Extended BASIC. Some features from Extended BASIC such as descriptive errors and user defined functions were not included, but there were double precision variables and the PRINT USING statement that we wanted to get in. The entire development of Level II BASIC took about four weeks from start to finish." The accompanying manual is more terse and technical than the Level I manual. Original Level I BASIC-equipped machines could be retrofitted to Level II through a ROM replacement performed by Radio Shack for a fee (originally $199). Users with Level I BASIC programs stored on cassette have to convert these to the tokenized Level II BASIC before use. A utility for this was provided with the Level II ROMS.

Disk BASIC allows disk I/O, and in some cases (NewDos/80, MultiDOS, DosPlus, LDOS) adds powerful sorting, searching, full screen editing, and other features. Level II BASIC reserves some of these keywords and issues a "?L3 ERROR", suggesting a behind-the-scenes change of direction intervened between the creation of the Level II ROMs and the introduction of Disk BASIC.

Microsoft also marketed an enhanced BASIC called Level III BASIC written by Bill Gates,[74] on cassette tape. The cassette contains a "Cassette File" version on one side and a "disk file" version on the second side for disk system users (which was to be saved to disk).[75] Level III BASIC adds most of the functions in the full 16 KB version of BASIC plus many other TRS-80 specific enhancements. Many of Level III BASIC's features are included in the TRS-80 Model III's Level II BASIC and disk BASIC.

Level I BASIC was still offered on the Model I in either 4K or 16K configurations after the introduction of Level II BASIC.

Other programming languages

Radio Shack published a combined assembler and program editing package called the Series I Assembler Editor.[76] 80 Micro magazine printed a modification enabling it to run under the Model 4's TRSDOS Version 6. Also from Radio Shack was Tiny Pascal.[77]

Microsoft made its Fortran, COBOL and BASCOM BASIC compiler available through Radio Shack.[76]

In 1982, Scientific Time Sharing Corporation published a version of its APL for the TRS-80 Model III as APL*PLUS/80.[78]

Other applications

Blackjack and backgammon came with the TRS-80, and at its debut Radio Shack offered four payroll, personal finance, and educational programs on cassette.[12][31]: 3 [13] Its own products' quality was often poor.[79] A critical 1980 80 Micro review of a text adventure described it as "yet another example of Radio Shack's inability to deal with the consumer in a consumer's market". The magazine added, "Sadly, too, as with some other Radio Shack programs, the instructions seem to assume that the reader is either a child or an adult with the mentality of a slightly premature corned beef".[80]

The more than 2,000 Radio Shack franchise stores as of September 1982 sold third-party hardware and software, but the more than 4,300 company-owned stores were at first prohibited from reselling or even mentioning products not sold by Radio Shack itself.[81][82][83][79][84][13] Green stated in 1980 that although "there are more programs for the 80 than for all other systems combined" because of the computer's large market share, "Radio Shack can't advertise this because they are trying as hard as they can to keep this fact a secret from their customers. They don't want the TRS-80 buyers to know that there is anything more than their handful of mediocre programs available", many of which "are disastrous and, I'm sure, doing tremendous damage to the industry".[85][86] Broderbund, founded that year, began by publishing TRS-80 software, but by 1983 cofounder Doug Carlston said that the computer "turned out to be a terrible market because most of the distribution networks were closed, even though there were plenty of machines out there".[87] Green wrote in 1982 that Apple had surpassed Tandy in sales and sales outlets despite the thousands of Radio Shack dealers because it supported third-party development, while "we find the Shack seeming to begrudge any sale not made by them and them alone".[79] Dealers not affiliated with Radio Shack preferred to sell software for other computers and not compete with the company; mail-order sales were also difficult, because company-owned stores did not sell third-party publications like 80 Micro.[82][13]

Charles Tandy reportedly wanted to encourage outside developers but after his death a committee ran the company, which refused to help outside developers, hoping to monopolize the sale of software and peripherals.[13] Leininger reportedly resigned because he disliked the company's bureaucracy after Tandy's death.[42] An author wrote in a 1979 article on the computer's "mystery of machine language graphics control" that "Radio Shack seems to hide the neat little jewels of information a hobbyist needs to make a treasure of the TRS-80". He stated that other than the "excellent" Level I BASIC manual "there has been little information until recently ... TRS-80 owners must be resourceful", reporting that the computer's "keyboard, video, and cassette" functionality were also undocumented.[72] The first book authorized by Tandy with technical information on TRSDOS for the Model I did not appear until after the computer's discontinuation.[84]

By 1982, the company admitted—after no software appeared for the Model 16 after five months—that it should have, like Apple, encouraged third-party developers of products like the killer app VisiCalc.[88][13] (A lengthy 1980 article in a Tandy publication introducing the TRS-80 version of VisiCalc did not mention that the spreadsheet had been available for the Apple II for a year.[89]) However, in the early 1980s, it was not uncommon for small companies and municipalities to write custom programs for computers such as the TRS-80 to process a variety of data. In one case a small town's vehicle fleet was managed from a single TRS-80.[90]

By 1985, the company's Ed Juge stated that other than Scripsit and DeskMate, "we intend to rely mostly on 'big-name', market proven software from leading software firms".[91] A full suite of office applications became available from the company and others, including the VisiCalc and Multiplan spreadsheets and the Lazy Writer, Electric Pencil, and from Radio Shack itself the Scripsit and SuperScripsit word processors.[92]

Compared to the contemporary Commodore and Apple micros, the TRS-80's block graphics and crude sound were widely considered limited. The faster speed available to the game programmer, not having to processor color data in high resolution, went a long way to compensating for this. TRS-80 arcade games tended to be faster with effects that emphasized motion. This perceived disadvantage did not deter independent software companies such as Big Five Software from producing unlicensed versions of arcade games like Namco's Galaxian, Atari's Asteroids,[93] Taito's Lunar Rescue, Williams's Make Trax,[94] and Exidy's Targ[58] and Venture. Sega's Frogger and Zaxxon were ported to the computer and marketed by Radio Shack.[95][94] Namco/Midway's Pac-Man was cloned by Philip Oliver and distributed by Cornsoft Group as Scarfman.[94][96] Atari's Battlezone was cloned for the Models I/III by Wayne Westmoreland and Terry Gilman and published by Adventure International as Armored Patrol.[97] They also cloned Eliminator (based on Defender) and Donkey Kong;[98] the latter wasn't published until after the TRS-80 was discontinued, because Nintendo refused to license the game.[94]

Some games originally written for other computers were ported to the TRS-80. Microchess has three levels of play and can run in the 4 KB of memory that is standard with the Model I; the classic ELIZA is another TRS-80 port. Both were offered by Radio Shack.[94][99] Apple Panic, itself a clone of Universal's Space Panic, was written for the TRS-80 by Yves Lempereur and published by Funsoft.[100] Epyx's Temple of Apshai runs slowly on the TRS-80.[94] Infocom ported its series of interactive text-based adventure games to the Models I/III; the first, Zork I, was marketed by Radio Shack.[95][94]

Adventure International's text adventures began on the TRS-80,[94] as did Sea Dragon by Westmoreland and Gilman, later ported to the other home micros.[citation needed] Android Nim by Leo Christopherson was rewritten for the Commodore PET and Apple.[citation needed] Many games are unique to the TRS-80, including Duel-N-Droids,[101] also by Christopherson, an early first-person shooter 13 Ghosts by Software Affair (the Orchestra-80, -85 and -90 people)[102][103][104] and shooters like Cosmic Fighter and Defence Command,[citation needed] and strange experimental programs such as Christopherson's Dancing Demon,[94][105] in which the player composes a song for a devil and choreographs his dance steps to the music.[106] Radio Shack offered simple graphics animation programs Micro Movie and Micro Marquee, and Micro Music.[99]

Radio Shack offered a number of programming utilities, including an advanced debugger, a subroutine package, and a cross reference builder.[107] Probably the most popular utility package was Super Utility written by Kim Watt of Breeze Computing.[108] Other utility software such as Stewart Software's Toolkit offered the first sorted directory, decoding or reset of passwords, and the ability to eliminate parts of TRSDOS that were not needed in order to free up floppy disk space. They also produced the On-Line 80 BBS, a TRSDOS based Bulletin Board System. Misosys Inc. was a prolific producer of sophisticated TRS-80 utility and language software for all models of TRS-80 from the very beginning.[109]

Perhaps because of the lack of information on TRSDOS[84] and its bugs,[13] by 1982 perhaps more operating systems existed for the TRS-80 than for any other computer.[110] TRSDOS is limited in its capabilities, since like Apple DOS 3.3 on the Apple II, it is mainly conceived of as a way of extending BASIC to support disk drives. Numerous alternative DOSes appeared, the most prominent being LDOS because Radio Shack licensed it from Logical Systems and adopted it as its official DOS for its Models I and III hard disk drive products. Other alternative TRS-80 DOSes included NewDOS from Apparat Personal Computers, and DoubleDOS, DOSPlus, MicroDOS, UltraDOS (later called Multidos). The DOS for the Model 4 line was originally called TRSDOS Version 6 but was actually produced by and licensed from Logical Systems, and is technically a descendant of the original Model I LDOS.

The memory map of the Model I and III render them incompatible with the standard CP/M OS for Z80 business computers, which loads at hexadecimal address $0000 with TPA (Transient Program Area) starting at $0100; the TRS-80 ROM resides in this address space. Omikron Systems' Mappers board remaps the ROM to run unmodified CP/M programs on the Model I. A customized version of CP/M is available, but loses its portability advantage.[111][112] 80 Micro magazine published a do-it-yourself CP/M modification for the Model III.[113]

Reception

Dan Fylstra, among the first owners, wrote in Byte in April 1978 that as an "'appliance' computer ... the TRS-80 brings the personal computer a good deal closer to the average customer", suitable for home and light business use. He concluded that it "is not the only alternative for the aspiring personal computer user, but it is a strong contender."[25] Jerry Pournelle wrote in 1980 that "the basic TRS-80 is a lot of computer for the money". He criticized the quality of Tandy's application and system software, and high cost of peripherals. Pournelle reported, however, that with the Omikron board, a customer paid less than $5000 for a computer compatible with TRS-80 and CP/M software "all without building a single kit".[111]

Three years later Pournelle was less positive about the computer. He wrote in May 1983, "As to our TRS-80 Model I, we trashed that sucker long ago. It was always unreliable, and repeated trips to the local Radio Shack outlet didn't help. The problem was that Tandy cut corners".[114] Pournelle wrote in July 1983:[84]

I'm a little bitter about my experiences with Tandy. I had genuinely thought that the Model I was the machine of the future: an inexpensive home computer that could be expanded by stages until it would do professional work. Of course it was never that. First, Tandy tried to fence in Model I users through that goofy operating system, and then it wouldn't let Radio Shack stores sell non-Tandy software. ... It had never been all that well designed, and when sales took off much faster than anticipated, the quality control system couldn't cope.

Compatible successors

For computers using the TRS-80 name, but unrelated to Models I, III, and 4, see List of TRS-80 and Tandy-branded computers.

Tandy replaced the Model I with the broadly compatible Model III in 1980. (The TRS-80 Model II is an entirely different and incompatible design).

Model III

TRS-80 Model III
 
ManufacturerTandy Corporation
TypeHome and small business computer
Release dateJuly 1980; 42 years ago (1980-07)
Introductory price
  • $699 (4KB RAM, Level I)
  • $999 (16K, Level II)
  • $2495 (48K, two 180 KB floppy drives, RS-232C)[115]
DiscontinuedSeptember 1983; 39 years ago (1983-09)
Operating systemTRSDOS 1.3, LDOS 5[116]
CPUZilog Z80A @ 2 MHz
Memory4 KB or 16, 32 or 48 KB
Display16 rows by 64 or 32 columns, block graphics
Graphicsoptional 512 by 192 pixels, $369 extra[117]
Soundoutput through cassette port
Backward
compatibility		Model I Z80 code ~ 80% (higher with patches), BASIC 100%
PredecessorModel I
SuccessorModel 4

Tandy released the TRS-80 Model III on July 26, 1980. The improvements of the Model III over the Model I include:[118] built-in lowercase, a better keyboard with repeating keys, an enhanced character set, a real-time clock, 1500-baud cassette interface, a faster (2.03 MHz) Z80 processor, and an all-in-one enclosure requiring fewer cables. A Model III with two floppy drives requires the use of only one electrical outlet; a two-drive Model I requires five outlets.[note 2] The Model III avoids the complicated power on/off sequence of the Model I. Shortly after the Model III's introduction, Model I production was discontinued as it did not comply with new FCC regulations as of January 1, 1981, regarding electromagnetic interference.[30][48][119][7][13]

Tandy distinguished between the high-end Model II[20] and Model III, describing the former as "an administrative system, good for things like word processing, data management and VisiCalc operations" and suitable for small businesses.[120] The lowest-priced version of the Model III was sold with 4 KB of RAM and cassette storage. The computer's CPU board has three banks of sockets (8 sockets to a bank) which take type 4116 DRAMs, so memory configurations come in 16 KB, 32 KB, or 48 KB RAM memory sizes. Computers with 32 KB or 48 KB RAM can be upgraded with floppy disk drive storage. There is space inside the computer cabinet for two full-height drives. Those offered by Tandy/Radio Shack are single-sided, 40 track, double-density (MFM encoding) for 180K of storage. Third-party suppliers offered double-sided and 80-track drives, though to control them they had to modify the TRSDOS driver code or else furnish an alternative third-party DOS which could (see below). The installation of floppy disk drives also requires the computer's power supply to be upgraded. There is no internal cooling fan in the Model III; it uses passive convection cooling (unless an unusual number of power-hungry expansions were installed internally, such as a hard disk drive, graphics board, speedup kit, RS-232 board, etc.).

Tandy claimed that the Model III was compatible with 80% of Model I software.[120] Many software publishers issued patches to permit their Model I programs to run on the Model III. Marketing director Ed Juge explained that their designers considered changing from the Model I's 64 column by 16 row video screen layout, but that they ultimately decided that maintaining compatibility was most important.[121]

The Model III's memory map and system architecture is mostly the same as the Model I, but the disk drives and printer port were moved from memory mapped to port I/O, thus Model I software that attempts to manipulate the disk controller directly or output to the printer (in particular Model I DOSes and application packages such as Visicalc and Scripsit) will not work. Under the supplied TRSDOS 1.3 operating system Model I disks can be read in the Model III, but not vice versa.[30] The optional LDOS OS (by Logical Systems Inc.) use a common disk format for both Model I and Model III versions.

Customers and developers complained of bugs in the Model III's Microsoft BASIC interpreter and TRSDOS.[120] Tandy/Radio Shack (and TRS-80 magazines like 80 Micro) periodically published many software patches to correct these deficiencies and to permit users to customize the software to their preferences.

Differences in the WD1771 and WD1791 floppy controllers created problems reading Model I disks on a Model III (the double-density upgrade in the Model I include both chips while a Model III had only the WD1791). The WD1771 supports four data markers while the WD1791 only supports two, and some versions of TRSDOS for the Model I also use them. In addition, they are used by copy protection schemes. Software was available to allow Model I disks to be read on a Model III. The WD1791 supports the 500 bit/s bitrate needed for high-density floppy drives, but the controller is not capable of using them without extensive modifications.

TRSDOS for the Model III was developed in-house by Radio Shack rather than being contracted out like the Model I's DOS. None of the code base from Model I DOS was reused and the Model III DOS was rewritten from scratch; this also created some compatibility issues since the Model III DOS's API was not entirely identical to the Model I DOS. This was primarily to avoid legal disputes with Randy Cook over ownership of the code as had occurred with Model I DOS and also because Radio Shack originally planned several features for the Model III such as 80 column text support that were not included. Two early versions, 1.1 and 1.2, were replaced by version 1.3 in 1981 which became the standard Model III OS. TRSDOS 1.3 is not format compatible with 1.1 and 1.2; a utility called XFERSYS is provided which converted older format disks to TRSDOS 1.3 format (this change is permanent and the resultant disks cannot be read with the older DOS versions).

The Model III's boot screen was cleaned up from the Model I. Instead of displaying garbage on screen at power up, it displays a "Diskette?" prompt if a bootable floppy is not detected. The user can insert a disk and press any key to boot. On powerup or reset holding down the Break key will boot the computer into ROM-based Level II BASIC. This ability is useful if the disk drive is not functioning and cannot boot a TRSDOS disk (or if a boot disk is not available); it permits an operator familiar with the machine hardware to perform diagnostics using BASIC's PEEK and POKE commands. This works for the Model 4 as well, but not for the 4P.

While Model I DOS is fairly flexible in its capabilities, Model III DOS is hard coded to only support 180K single sided floppies, a problem fixed by the many third party DOSes. To that end, when Radio Shack introduced hard disks for the TRS-80 line in 1982, the company licensed LDOS rather than attempt to modify Model III DOS for hard disk support.

Level II BASIC on the Model III is 16 KB in size and incorporates a few features from Level I Disk BASIC.

TRSDOS 1.3 was given a few more minor updates, the last being in 1984, although the version number was unchanged. This includes at least one update that writes an Easter Egg message "Joe, you rummy buzzard" on an unused disk sector, which is reputedly a joke message left by a programmer in a beta version, but accidentally included in the production master.[122]

The Model III keyboard lacks CONTROL. Many application programs use @, while others use ⇧ Shift+↑. Often CLEAR is used in combination with number and alpha keys. The Model III keyboard also lacks ⇪ Caps Lock; to caps-lock the alpha keys the user presses ⇧ Shift+0. Under LDOS typeahead is supported.

Because TRSDOS 1.3 was found wanting by many users, Tandy offered (at added cost) Logical System's LDOS Version 5 as an alternative. As with the Model I, other third-party sources also offered TRSDOS alternatives for the Model III, including NewDOS, Alphabit's MultiDOS, and Micro Systems Software's DOSPlus. These are compatible with TRSDOS 1.3 and ran the same applications programs, but offer improved command structures, more and better system utilities, and enhancements to the Microsoft BASIC interpreter. After writing the original Model I TRSDOS, Randy Cook began work on his own DOS, titled VTOS, which was superseded by LDOS and also created some frustration for users as it is the only TRS-80 DOS to be copy protected.

Although mostly intended as a disk-based computer, the Model III was available in a base cassette configuration with no disk hardware and only 16 KB of RAM with Level II BASIC. Radio Shack also offered a 4K version with Level I BASIC, identical to Model I Level I BASIC, but with the addition of LPRINT and LLIST commands for printer output. Upgrading to a disk machine necessitate installing at least 32 KB of RAM, the disk controller board, and another power supply for the disk drives. Disk upgrades purchased from Radio Shack included TRSDOS 1.3; users upgrading from third-party vendors had to purchase DOS separately (most opted for LDOS or DOSPlus), though a great many Model III applications programs included a licensed copy of TRSDOS 1.3.

As with the Model I's E/I, the RS-232C port on the Model III was an extra cost option and not included in the base price of the computer, though the dual disk Model III for $2495 included the serial port.

Like the Model I, the Model III sold well in the educational market. Many school administrators valued the Model III's all-in-one hardware design because it made it more difficult for students to steal components.[13] InfoWorld approved of the Model III's single-unit design, simplified cable management, and improvements such as lack of keyboard bounce and improved disk reliability. The reviewer, a former Model I owner, stated "I'm impressed" and that "had the Model III been available, it's probable that I wouldn't have sold it". He concluded, "If you're looking for a computer that's not too expensive but that performs well, you would be wise to test the Model III—you might end up buying it."[48]

Don French, who had left Radio Shack to found FMG Software after designing the Model I, expressed his disappointment in the new machine while trying to convert CP/M to run on it. "I've encountered numerous problems with the floppy drive and its interface. Radio Shack will sell a Model III to anyone. They're trying to market it as a business computer when the existing software is woefully inadequate. 48K just isn't enough. You run out of memory before you get going. They're selling a medical package that takes up nine disks. I think the Model III is a very poorly conceived machine".[120]

Aftermarket products

Aftermarket hardware were offered by Tandy/Radio Shack and many third-party manufacturers. The usual selection of add-ons and peripherals available for the Model I were offered: outboard floppy drives (one or two could be plugged into a card-edge connector on the back panel), an outboard hard disk drive (LDOS was furnished as Tandy's hard drive OS vice TRSDOS), a high-resolution graphics board[123] (resolution 512 by 192 pixels),[note 3] an RS-232C serial port on an internal circuit card, and a parallel printer (connected by a card-edge connector). A popular hardware/software add-on was the Orchestra-90[124][125][126] music synthesizer. It can be programmed to play up to five voices with a range of six octaves stereophonically. A great many Orch-90 (as it was often called) music files were available for download from CompuServe. The Orch-90 was licensed from a company called Software Affair, which also produced the Model I-compatible Orchestra-85 from 1981.

At least three vendors produced CP/M modifications for the Model III, Omikron (also a Model I mod), Holmes Engineering, and Memory Merchant.[127] Options were available for upgrading the CRT to the CP/M professional standard of 80 columns and 24 rows, as well as eight inch floppy drives.

A number of third-party manufacturers specialized in upgrading Model IIIs with high performance hardware and software, and remarketing them under their own labels.[128][note 4] The improvements typically included internal hard disk drives, greater capacity floppy drives, 4 MHz Z80 speedup kits, professional grade green or amber CRT video displays, better DOS software (typically DOSPlus by Micro Systems Software or LDOS by Logical Systems) including the all-important hard drive backup utilities, and custom menu-driven shell interfaces which insulated non-expert users (business employees) from the DOS command line. These were touted as high productivity turnkey systems for small businesses at less cost than competing business systems from higher-end providers such as IBM and DEC, as well as Radio Shack's own TRS-80 Model II.

Model 4

Main article: TRS-80 Model 4
 
TRS-80 Model 4 (standard version)
 
TRS-80 Model 4P

The successor to the Model III is the TRS-80 Model 4 released in April 1983. It has faster Z80A 4 MHz CPU,[129] a larger video display 80 columns x 24 rows with reverse video, bigger keyboard, internal speaker, and its 64 KB of RAM can be upgraded to 128 KB of bank-switched RAM. The display can be upgraded with a high resolution graphics card yielding 640 × 240 pixels. The Model 4 is fully compatible with Model III and CP/M application software. A diskless Model 4 (with 16 KB RAM and Level II BASIC) cost $999, with 64 KB RAM and one single-sided 180K disk drive $1,699, and two drives with RS-232C $1,999; an upgrade for Model III owners cost $799 and provided a new motherboard and keyboard.[73] Tandy sold 71,000 in 1984.[130]

The Model 4 includes all of the Model III's hardware, port assignments, and operating modes, making it 100% compatible. Model III programs running on a Model 4 can access the Model 4's added hardware features (like 4 MHz clock rate, bigger video screen and keyboard, banked RAM above 64 KB). There were aftermarket software packages that made this ability available to non-programmer users.[131][132]

The Model 4P is a transportable version introduced in September 1983 and discontinued in early 1985. It is functionally the same as the dual-drive desktop model but lacks the card edge connector for two outboard diskette drives and for cassette tape interface. It has a slot for an internal modem card and could emulate a Model III.

The Model 4D with bundled Deskmate productivity suite was introduced in early 1985. It has a revised CPU board using faster gate array logic which includes the floppy controller and RS-232C circuitry, all on a single board. The computer has two internal double-sided diskette drives, and is the last model descended from the 1977 Model I. It retailed for $1,199 at its introduction in 1985. During 1987–1988 the retail stores removed the Model 4Ds from display but they were available by special order through 1991.

 
DGT-100 by DIGITUS Ind. Com. Serv. de Eletrônica Ltda., one of a dozen brands of TRS-80 clones made by other companies.

See also

Note

  1. ^ The user must take care not to do anything that could cause memory to be overwritten; they should recover immediately without running any other programs. Since programs may start automatically via the TRSDOS AUTO command, during a spontaneous reboot they take the precaution of holding down ↵ Enter to prevent this from happening. It takes TRSDOS some half dozen seconds to load from floppy disk; the user has this long to keep an AUTO'd program from loading. This star parameter became a standard for many software applications running on the Models III and 4; for instance LS-DOS's TED and Prosoft's Allwrite.
  2. ^ One outlet each for the CPU/keyboard, Expansion Interface, Video Monitor, and the drives.
  3. ^ The Radio Shack catalog entry advertises 640x240 resolution, but this is a misprint
  4. ^ It was necessary to rebrand these highly modified Model IIIs because Radio Shack enforced a strict policy that no repair service would be performed on nonstandard RS products.

References

  1. ^ a b Forster, Winnie (2005). The encyclopedia of consoles, handhelds & home computers 1972–2005. Gameplan. p. 17. ISBN 3-00-015359-4.
  2. ^ Advertisement:Radio Shack. Computerworld. October 15, 1979. How we sold over 100,000 TRS-80 Model I Systems
  3. ^ "Table 2: United States (1978-1982)". Computers and People. Berkeley Enterprises. 33–36: 19. 1984. TRS-80 (all models) 2,400,000
  4. ^ a b McCracken, Harry (August 3, 2012). "Please Don't Call It Trash-80: A 35th Anniversary Salute to Radio Shack's TRS-80". Time.
  5. ^ Mooallem, Jon (April 19, 2010). "The Lost Tribes of RadioShack: Tinkerers Search for New Spiritual Home". Wired. Retrieved August 3, 2012.
  6. ^ a b c d e Welch, David and Theresa (2007). Priming the Pump: How TRS-80 Enthusiasts Helped Spark the PC Revolution. Ferndale, Michigan: The Seeker Books. ISBN 978-0-9793468-0-4.
  7. ^ a b c "TRS-80 Microcomputer News". January 1981. Retrieved March 7, 2015. [In November we] announced that manufacturing of the Model I computer would stop prior to the end of 1980 [primarily because] to meet the new FCC regulations we would have had to redesign the entire product, case and all [which would have made] the cost of the Model I as much as the Model III {{cite journal}}: Cite journal requires |journal= (help)
  8. ^ a b "Radio Shack TRS-80 Micro Computer System". oldcomputer.org. Retrieved May 6, 2010.
  9. ^ obituary, John Roach, Pioneer of the Personal Computer, Is Dead at 83, The New York Ledger, Business, March 24, 2022
  10. ^ Texas Christian University, "John V. Roach Honors College". Archived from the original on 2018-05-27. Retrieved 2018-05-26
  11. ^ a b c d e Swaine, Michael (August 31, 1981). "How the TRS-80 Was Born". InfoWorld. Vol. 3, no. 17. pp. 40–43. Retrieved February 28, 2011.
  12. ^ a b c d e f g h i j Thomas, Wes (September–October 1977). "Radio Shack's $600 Home Computer". Creative Computing. pp. 94–95.
  13. ^ a b c d e f g h i j k l m n o p q r s t White, Ron (August 1987). "The Tandy Story: It all started 10 years ago in a converted used-car showroom..." 80 Micro. pp. 50–64. Retrieved May 18, 2019.
  14. ^ a b c Reed, Matthew. "The Introduction of the TRS‑80 (Part 1)". TRS-80.org. Retrieved January 23, 2015.
  15. ^ a b c Leininger, Steven W. (September 1977). . San Diego Computer Society. Archived from the original on May 31, 2012. Retrieved February 28, 2011.
  16. ^ a b c d Ahl, David (November 1984). "Tandy Radio Shack enters the magic world of computers". Creative Computing. p. 292. Retrieved February 26, 2011.
  17. ^ a b c d Reed, Matthew. "The Introduction of the TRS‑80 (Part 2)". TRS-80.org. Retrieved January 23, 2015.
  18. ^ Rothman, Lile. . Time. Archived from the original on August 3, 2015.
  19. ^ a b c Brown, Chris (January 1980). "The Tandy Story". 80 Microcomputing. pp. 28–30. Retrieved October 17, 2013.
  20. ^ a b c Freiberger, Paul (August 31, 1981). "Radio Shack Prepares for the Future". InfoWorld. Vol. 3, no. 17. pp. 51, 53–54. Retrieved October 26, 2016.
  21. ^ a b c d Bartimo, Jim (August 20, 1984). "Radio Shack Polishes Its Image". InfoWorld. Vol. 6, no. 34. pp. 47–52. Retrieved February 28, 2011.
  22. ^ "Computer fair comes to Boston". Personal Computing Magazine. May 1, 1977. Retrieved March 7, 2021. If you are going to be anywhere all the computer buffs from near Boston on August 4th, 5th or 6th, you may want to get over to Boston University. They are going to have a PERSONAL COMPUTING show complete with exhibits, seminars and everything that's new and up to date that you can see, touch, feel and play with in home computing. And just because Boston suburbia has more colleges and universities per square foot than any other region of the United States doesn't mean that this computing show is just for high school, college students and their professors. To be sure, MIT, Tufts, Harvard, Boston College, Brandeis, Emerson, Simmons, Northeastern, Babson, University of Massachusetts, Bentley, Wentworth, Lincoln, Emmanuel, Lesley, Curry, Radcliff, Jackson, Suffolk, Wheelock and so forth will be there. B.U. is organizing the fair to be of interest for everybody in personal computing.
  23. ^ Clinton Pardons Terror. The New York Post. 1999-08-13. Retrieved 2017-08-03.
  24. ^ a b "Computers May Soon Be In Homes". Lakeland Ledger. Associated Press. August 6, 1977. pp. 1A. Retrieved January 23, 2015.
  25. ^ a b c d e f g Fylstra, Dan (April 1978). "The Radio Shack TRS-80: An Owner's Report". Byte. Vol. 3, no. 4. p. 49. Retrieved October 17, 2013.
  26. ^ Pérez, Gina M. (2005). Fuerzas Armadas de Liberación Nacional (FALN). Encyclopedia of Chicago. Chicago Historical Society.
  27. ^ "Blast from the Computer's Past". World Technology Computer Repair and Service. World Technology, LLC. August 3, 2017. Retrieved March 7, 2021.
  28. ^ "Introduction of the TRS-80 at the Boston Personal Computer Faire in 1977. (Photo)". Lawrence Hageman Forums. Retrieved March 7, 2021.
  29. ^ a b "To the Doctor, the Lawyer, the Butcher, the Baker, the Candlestick Maker, and Everyone Else". The Galveston Daily News (advertisement). May 26, 1978. pp. 3–A. Retrieved October 6, 2015.
  30. ^ a b c Hogan, Thom (August 31, 1981). "A Look at Radio Shack's Five Computers". InfoWorld. Vol. 3, no. 17. pp. 44–45. Retrieved February 28, 2011.
  31. ^ a b c . Radio Shack. 1977. Archived from the original on July 15, 2011. Retrieved March 14, 2011.
  32. ^ Righthand, Jess (August 3, 2010). "August 3, 1977: The TRS-80 Personal Computer Goes on Sale". Smithsonian. Retrieved January 23, 2015.
  33. ^ Baker, Joe (April 28, 1978). "Microcomputer stirs interest". The San Bernardino County Sun. pp. B-19. Retrieved October 6, 2015.
  34. ^ "TRS-80 Microcomputer System Model I 16k Level II - Computer - Computing History". www.computinghistory.org.uk.
  35. ^ . Byte. September 1995. Archived from the original on June 18, 2008. Retrieved June 10, 2008.
  36. ^ a b . Radio Shack Catalogs dot com. Tandy/Radio Shack. Archived from the original on May 31, 2017. Retrieved December 1, 2022.
  37. ^ "Radio Shack Computer Catalog RSC-2, page 20". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  38. ^ Green, Wayne (October 1980). "Publisher's Remarks". Kilobaud Microcomputing. pp. 6–9. Retrieved June 23, 2014.
  39. ^ Hogan, Thom (August 31, 1981). "From Zero to a Billion in Five Years". InfoWorld. Vol. 3, no. 17. pp. 6–7. Retrieved February 15, 2015.
  40. ^ Lundell, Allan (August 31, 1981). "TRS-80 Outcrop Companies Evolve". InfoWorld. Vol. 3, no. 17. pp. 46–47. Retrieved February 15, 2015.
  41. ^ Osborne, Adam (April 13, 1981). "The Portable Osborne". InfoWorld. Vol. 3, no. 17. pp. 42–43. Retrieved January 1, 2015.
  42. ^ a b Markoff, John (October 5, 1981). "TRS-80 Co-creator to Leave Tandy". InfoWorld. Vol. 3, no. 20. pp. 1, 6. Retrieved March 20, 2020.
  43. ^ . Consumer Electronics Association. Archived from the original on July 9, 2007. Retrieved February 26, 2011.
  44. ^ Reed, Matthew. "What does S-80 mean?". Retrieved February 26, 2020.
  45. ^ "TRS-80 Microcomputer News". September 1980. Retrieved March 7, 2015. First of all the Model I is not dropped, it is in the 1981 Radio Shack Annual catalog and the price is unchanged. {{cite journal}}: Cite journal requires |journal= (help)
  46. ^ "John Freire audio interview discussing the use of an AM radio for game sounds on the Model I". digibarn.com. Retrieved July 20, 2010.
  47. ^ "1984 Radio Shack Computer Catalog RSC-10 page 27". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved November 30, 2022.
  48. ^ a b c d e f Hogan, Thom (August 31, 1981). "The Radio Shack TRS-80 Model III Computer". InfoWorld. Vol. 3, no. 17. pp. 35–37. Retrieved February 28, 2011.
  49. ^ a b c d Green, Wayne (January 1980). "Where We're Coming From / Where We're Bound". 80 Micro. p. 8. Retrieved October 17, 2013.
  50. ^ a b Reed, Matthew. "Model I Keybounce". TRS-80.org. Retrieved May 20, 2019.
  51. ^ a b c Barden, William Jr. (June 1980). "The Assembly Line". 80 Micro. pp. 22, 24. Retrieved October 14, 2021.
  52. ^ Mazur 1983, p. 386.
  53. ^ Mazur 1983, p. 294, 297.
  54. ^ Technical Reference Handbook 1982, pp. 34, 96–97.
  55. ^ Mazur 1983, pp. 258–259.
  56. ^ Mazur 1983, pp. 28, 313–314.
  57. ^ Reed, Matthew. "The Electric Pencil Lower Case Modification". Retrieved February 27, 2016.
  58. ^ a b Williams, Gregg (September 1981). "Big Five Software". Byte. Vol. 6, no. 9. pp. 384–386. Retrieved October 19, 2013.
  59. ^ 1978 Radio Shack Tandy TRS-80 Computer Catalog RSC-02. Radio Shack. 1978.
  60. ^ "Radio Shack Computer Catalog RSC-3, page 10". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  61. ^ "Radio Shack Computer Catalog RSC-2. page 13". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  62. ^ "Radio Shack Computer Catalog RSC-2, page 19". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved November 30, 2022.
  63. ^ "Radio Shack Computer Catalog RSC-2, page 15". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  64. ^ "Radio Shack Computer Catalog RSC-2, page 14". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  65. ^ Ciarcia, Steve (February 1982). "Build the Disk-80: Memory Expansion and Floppy-Disk Control". Byte. Vol. 6, no. 3. p. 36. Retrieved October 18, 2013.
  66. ^ Lundell, Allan (August 31, 1981). "Stringy Floppy from Exatron". InfoWorld. Vol. 3, no. 17. pp. 47–48. Retrieved February 15, 2015.
  67. ^ "Radio Shack Computer Catalog RSC-8, page 52". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  68. ^ McKay, Bryan (January 2, 1986). DDIR read-me. p. 1.
  69. ^ "Radio Shack Computer Catalog RSC-2, page 16". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  70. ^ "GitHub - human39/fp-215-plotter: Radio Shack TRS-80 FP-215 Flatbed Plotter Info". August 11, 2019 – via GitHub.
  71. ^ Lien, David A. (1978). User's Manual for Level 1. p. 1.
  72. ^ a b Yeager, George H (August 1979). "Exploring TRS-80 Graphics". Byte. Vol. 4, no. 8. pp. 82–84.
  73. ^ a b Archer, Rowland Jr. (October 1983). "Radio Shack's TRS-80 Model 4". Byte. Vol. 8, no. 10. pp. 292–302. Retrieved January 31, 2015.
  74. ^ Program Instructions for Level III BASIC. Microsoft Consumer Products. 1979. p. 1.
  75. ^ Program Instructions for Level III BASIC. Microsoft Consumer Products. 1979. p. 11.
  76. ^ a b "1982 Radio Shack Computer Catalog RSC-6 page 11". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 1, 2022.
  77. ^ "1982 Radio Shack Computer Catalog RSC-6 page 9". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved May 1, 2019.
  78. ^ Gates, Phelps (March 1983). "A microcomputer APL*PLUS system implementation". ACM SIGAPL APL Quote Quad. 13 (3): 201–204. doi:10.1145/390005.801217.
  79. ^ a b c Green, Wayne (December 1982). "Is the Shack in real trouble?". 80 Micro (editorial). pp. 8, 10, 12. Retrieved February 29, 2020.
  80. ^ O'Brien, William (August 1980). "Pyramid". 80 Micro. No. 8. p. 21. Retrieved February 12, 2015.
  81. ^ Shuford, Dan B. (February 1980). "The Bottom Shelf: Software For All Seasons". 80 Micro. No. 2. pp. 36–37. Retrieved October 17, 2013.
  82. ^ a b Green, Wayne (August 1981). "Tandy Growth Retarded". 80 Micro. No. 20. p. 10. Retrieved May 28, 2019.
  83. ^ Shea, Tom (September 13, 1982). "All others sell at list price; we deal". InfoWorld. Vol. 4, no. 36. p. 11. Retrieved March 17, 2019.
  84. ^ a b c d Pournelle, Jerry (July 1983). "Interstellar Drives, Osborne Accessories, DEDICATE/32, and Death Valley". Byte. Vol. 8, no. 7. p. 323. Retrieved August 28, 2016.
  85. ^ Green, Wayne (August 1980). "80 Remarks". 80 Micro. No. 8. p. 8. Retrieved February 12, 2015.
  86. ^ Green, Wayne (November 1980). "Publisher's Remarks". Kilobaud. pp. 6–8. ISSN 0192-4575. Retrieved June 23, 2014.
  87. ^ Barry, David (October 1983). "Profiles: The Carlston Trio". Antic. Retrieved July 1, 2021.
  88. ^ Markoff, John (July 5, 1982). "Radio Shack: set apart from the rest of the field". InfoWorld. Vol. 4, no. 26. p. 36. Retrieved February 10, 2015.
  89. ^ Reed, Matthew. "VisiCalc". TRS-80.org. Retrieved January 23, 2015.
  90. ^ Clack, Jeff (April 1, 1983). "Vehicle Maintenance - How the City of Lander, WY keeps tracke on their Model III". 80-U.S. 80-Northwest Publishing. Retrieved October 9, 2019.
  91. ^ Juge, Ed (October 1985). "News for the top: what's really going on at Tandy". Creative Computing. p. 108. Retrieved October 14, 2016.
  92. ^ "1982 Radio Shack Computer Catalog RSC-6 page 10". Radio Shack Catalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  93. ^ "Super Nova". TRS-80 dot org. Matthew Reed. Retrieved December 1, 2022.
  94. ^ a b c d e f g h i Dobson, Dale (November 26, 2012). "Games from the Trash: The History of the TRS-80". Gamasutra. Retrieved May 13, 2019.
  95. ^ a b "Radio Shack Computer Catalog RSC-12 page 31". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  96. ^ ""Software" Category - page 4: Scarfman". TRS-80 dot org. Matthew Reed. Retrieved May 8, 2019.
  97. ^ "Armored Patrol". TRS-80 dot org. Matthew Reed. Retrieved May 7, 2019.
  98. ^ "Search Results for "eliminator", Donkey Kong". TRS-80 dot org. Matthew Reed. Retrieved May 8, 2019.
  99. ^ a b "1982 Radio Shack Computer Catalog RSC-6 page 8". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  100. ^ ""Software" Category - page 5: Apple Panic". TRS-80 dot org. Matthew Reed. Retrieved May 8, 2019.
  101. ^ "Duel-N-Droids". videogamegeek dot com. BoardGameGeek, LLC. Retrieved May 14, 2019.
  102. ^ Mitchell, Robert (November 1984). "Ghost Busting". 80 Micro. CW Communications. p. 192. Retrieved July 15, 2020.
  103. ^ "13 Ghosts (TRS-80)". mobygames dot com. Blue Flame Labs. Retrieved May 14, 2019.
  104. ^ "1985 Radio Shack Computer Catalog RSC-14 page 36". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  105. ^ "Dancing Demon". www.dnull.com.
  106. ^ Cooper, Elizabeth; Kolya, Yvon (May 1981). "Dancing Demon from Radio Shack". Byte. Vol. 6, no. 5. p. 148. Retrieved October 18, 2013.
  107. ^ "Radio Shack Computer Catalog RSC-7 page 9". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  108. ^ "Super Utility". TRS-80 dot org. Matthew Reed. Retrieved May 7, 2019.
  109. ^ "Misosys 1992 Catalog page 1" (PDF). tim-mann dot org. Roy Soltoff/Misosys Inc. Retrieved May 8, 2019.
  110. ^ Archer, Rowland Jr. (December 1982). "Multidos / A New TRS-80 Disk Operating System". Byte. Vol. 7, no. 12. pp. 392–397. Retrieved February 6, 2015.
  111. ^ a b Pournelle, Jerry (July 1980). "Omikron TRS-80 Boards, NEWDOS+, and Sundry Other Matters". Byte. Vol. 5, no. 7. p. 198. Retrieved October 18, 2013.
  112. ^ Theresa Welsh, David Welsh Priming the Pump: How TRS-80 Enthusiasts Helped Spark the PC Revolution, The Seeker Books, 2007,ISBN 0979346819, Chapter 2 The DOS Wars
  113. ^ Brewer, Bill (March 1983). "CP/M Cheap". 80 Micro. CW Communications. pp. 112–122. Retrieved July 19, 2020.
  114. ^ Pournelle, Jerry (May 1983). "Ulterior Motives, Lobo, Buying Your First Computer, JRT Update". Byte. Vol. 8, no. 5. pp. 298–324.
  115. ^ "1981 Radio Shack Computer Catalog RSC-4 pages 5-6". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved May 21, 2019.
  116. ^ "Radio Shack Computer Catalog RSC-8 page 40". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  117. ^ "Radio Shack Computer Catalog RSC-8 page 52". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  118. ^ "1981 Radio Shack Computer Catalog RSC-4, pg. 5". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  119. ^ Robertson, Nancy (December 1980). "Model I Caught By FCC Fallout". 80 Micro. No. 12. pp. 51, 56. Retrieved March 21, 2011.
  120. ^ a b c d Freiberger, Paul (August 31, 1981). "Bugs in Radio Shack TRS-80 Model III: How Bad Are They?". InfoWorld. Vol. 3, no. 17. p. 49. Retrieved February 28, 2011.
  121. ^ Juge, Ed (September 1980). "Inside 80". 80 Micro. No. 9. CW Communications. pp. 10–11. Retrieved May 22, 2019.
  122. ^ "The TRSDOS "rummy buzzard" release". www.trs-80.org.
  123. ^ "1983 Radio Shack Computer Catalog RSC-8, page 52". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  124. ^ "Orchestra-90". trs80 dot org. Matthew Reed. Retrieved May 3, 2017.
  125. ^ "1985 Radio Shack Computer Catalog RSC-12, page 31". radioshackcatalogs dot com. Tandy/Radio Shack. Retrieved December 2, 2022.
  126. ^ Ludwig, Gary A. (March 1985). "Let There Be Music". 80 Micro. CW Communications. p. 114. Retrieved July 9, 2020.
  127. ^ Kepner, Terry (December 1983). "CP/M III Ways". 80 Micro. CW Communications. p. 122. Retrieved July 17, 2020.
  128. ^ "The Muscle Micros, These Three Sleek Supercharged Model IIIs..." 80 Micro. April 1983. pp. 81–94. Retrieved May 22, 2019.
  129. ^ "TRS-80 Computers: TRS-80 Model 4". Trs-80.com. March 4, 2009. Retrieved August 13, 2013.
  130. ^ Bartimo, Jim (March 11, 1985). "Tandy Revamps Product Line". InfoWorld. Vol. 7, no. 10. pp. 28–29. Retrieved January 21, 2015.
  131. ^ Soltoff, Roy. "The Misosys Quarterly Vol. I.iii pg. 6, "LDOS 5.3 Model 4 Hardware Interface Kit"" (PDF). tim-mann dot org. Misosys, Inc. Retrieved November 12, 2019.
  132. ^ Dalton, David (September 1985). "The Enhancer". 80 Micro (product review). CW Communications. p. 33. Retrieved November 12, 2019.

Further reading

  • TRS-80 Micro Computer Technical Reference Handbook (2nd ed.). Radio Shack. 1982. Retrieved October 14, 2021.
  • Mazur, Ken (1983). The Creative TRS-80. Creative Computing Press. ISBN 9780916688363. Retrieved October 14, 2021.

External links

 
Wikimedia Commons has media related to TRS-80 Models I, III and 4.
  • TRS-80 at Curlie
  • Radio Shack Catalog Archive (1939–2011)
  • trs-80.com : Ira Goldklang's TRS-80 Revived Site
  • REM 80 – The North West TRS-80 USers Group Magazines
  • TRS-80 Emulator in Javascript : online emulation of Model III BASIC & commercial arcade games
  • jTandy, another javascript TRS-80 emulator : online emulation of Model III BASIC & commercial arcade games
  • Tandy Model 4/4P Technical Reference
  • LDOS 5.1 User Manual
  • Byte magazine review of LDOS 5.1
  • "Guide to the Radio Shack collection". Computer History Museum. Online Archive of California, California Digital Library. 2004.

December 31, 2022
this, article, about, original, model, successors, models, overview, computers, using, tandy, names, list, tandy, branded, computers, other, uses, disambiguation, micro, computer, system, later, renamed, model, distinguish, from, successors, desktop, microcomp. This article is about the original TRS 80 Model I and its successors Models III and 4 For an overview of all computers using the TRS 80 and Tandy names see List of TRS 80 and Tandy branded computers For other uses see TRS 80 disambiguation The TRS 80 Micro Computer System TRS 80 later renamed the Model I to distinguish it from successors is a desktop microcomputer launched in 1977 and sold by Tandy Corporation through their Radio Shack stores The name is an abbreviation of Tandy Radio Shack Z80 microprocessor 4 It is one of the earliest mass produced and mass marketed retail home computers 5 TRS 80 Model ITRS 80 Model I with Expansion Interface and displayManufacturerTandy CorporationTypeHome computerRelease dateAugust 3 1977 45 years ago 1977 08 03 1 Lifespan1977 1981 4 yearsIntroductory priceUS 599 95 equivalent to 2 680 in 2021 DiscontinuedJanuary 1981 41 years ago 1981 01 Units sold100 000 as of 1979 2 2 4 million all models 3 Operating systemTRSDOS LDOS NewDos 80 Level I BASICCPUZilog Z80 1 774 MHzMemory4 48 KBDisplayMonochrome 12 CRT 64 16 character semigraphicsSoundSquare wave tonesThe TRS 80 has a full stroke QWERTY keyboard the Zilog Z80 processor 4 KB dynamic random access memory DRAM standard memory small size and desk area floating point Level I BASIC language interpreter in read only memory ROM 64 character per line video monitor and a starting price of US 600 1 equivalent to US 2 700 in 2021 A cassette tape drive for program storage was included in the original package While the software environment was stable the cassette load save process combined with keyboard bounce issues and a troublesome Expansion Interface contributed to the Model I s reputation as not well suited to serious use It lacked support for lowercase characters which also hampered business adoption An extensive line of upgrades and add on hardware peripherals for the TRS 80 was developed and marketed by Tandy Radio Shack The basic system can be expanded with up to 48 KB of RAM in 16 KB increments and up to four floppy disk drives and or hard disk drives Tandy Radio Shack provided full service support including upgrade repair and training services in their thousands of stores worldwide By 1979 the TRS 80 had the largest selection of software in the microcomputer market 6 Until 1982 the TRS 80 was the best selling PC line outselling the Apple II series by a factor of five according to one analysis 4 In mid 1980 the broadly compatible TRS 80 Model III was released The Model I was discontinued shortly thereafter primarily due to stricter Federal Communications Commission FCC regulations on radio frequency interference to nearby electronic devices 7 8 In April 1983 the Model III was succeeded by the compatible TRS 80 Model 4 Following the original Model I and its compatible descendants the TRS 80 name became a generic brand used on other unrelated computer lines sold by Tandy including the TRS 80 Model II TRS 80 Model 2000 TRS 80 Model 100 TRS 80 Color Computer and TRS 80 Pocket Computer Contents 1 History 1 1 Development 1 2 Announcement 1 3 Delivery 1 4 Model II and III 2 Hardware 2 1 Keyboard 2 2 Video and audio 3 Peripherals 3 1 Cassette tape drive 3 2 Model I Expansion Interface 3 3 Floppy disk drives 3 4 Exatron Stringy Floppy 3 5 Hard drive 3 6 Printers 4 Software 4 1 BASIC 4 2 Other programming languages 4 3 Other applications 5 Reception 6 Compatible successors 6 1 Model III 6 1 1 Aftermarket products 6 2 Model 4 7 See also 8 Note 9 References 10 Further reading 11 External linksHistory EditDevelopment Edit Tandy Radio Shack TRS 80 Model I In the mid 1970s Tandy Corporation s Radio Shack division was a successful American chain of more than 3 000 electronics stores Among the Tandy employees who purchased a MITS Altair kit computer was buyer Don French who began designing his own computer and showed it to vice president of manufacturing John V Roach Tandy s former electronic data processing manager 9 10 Although the design did not impress Roach the idea of selling a microcomputer did When the two men visited National Semiconductor in California in mid 1976 Homebrew Computer Club member Steve Leininger s expertise on the SC MP microprocessor impressed them National executives refused to provide Leininger s contact information when French and Roach wanted to hire him as a consultant but they found Leininger working part time at Byte Shop Leininger was unhappy at National his wife wanted a better job and Texas did not have a state income tax Hired for his technical and retail experience Leininger began working with French in June 1976 The company envisioned a kit but Leininger persuaded the others that because too many people can t solder a preassembled computer would be better 11 12 13 14 Tandy had 11 million customers that might buy a microcomputer but it would be much more expensive than the US 30 median price of a Radio Shack product and a great risk for the very conservative company 14 13 Executives feared losing money as Sears did with Cartrivision 15 and many opposed the project one executive told French Don t waste my time we can t sell computers As the popularity of CB radio at one point comprising more than 20 of Radio Shack s sales declined however the company sought new products In December 1976 French and Leininger received official approval for the project but were told to emphasize cost savings for example leaving out lowercase characters saved US 1 50 in components and reduced the retail price by US 5 The original US 199 retail price required manufacturing cost of US 80 the first design had a membrane keyboard and no video monitor Leininger persuaded Roach and French to include a better keyboard it a monitor datacassette storage and other features required a higher retail price to provide Tandy s typical profit margin In February 1977 they showed their prototype running a simple tax accounting program to Charles Tandy head of Tandy Corporation The program quickly crashed as the computer s implementation of Tiny BASIC could not handle the US 150 000 figure that Tandy typed in as his salary and the two men added support for floating point math to its Level I BASIC to prevent a recurrence The project was formally approved on 2 February 1977 Tandy revealed that he had already leaked the computer s existence to the press When first inspecting the prototype he remarked that even if it did not sell the project could be worthy if only for the publicity it might generate 16 13 14 MITS sold 1 000 Altairs in February 1975 and was selling 10 000 a year When Charles Tandy asked who would buy the computer company president Lewis Kornfeld admitted that they did not know if anyone would but suggested that small businesses and schools might Knowing that demand was very strong for the US 795 Altair which cost more than 1 000 with a monitor Leininger suggested that Radio Shack could sell 50 000 computers 17 13 but no one else believed him Roach called the figure horseshit as the company had never sold that many of anything at that price Roach and Kornfeld suggested 1 000 to 3 000 per year 3 000 was the quantity the company would have to produce to buy the components in bulk Roach persuaded Tandy to agree to build 3 500 the number of Radio Shack stores so that each store could use a computer for inventory purposes if they did not sell 6 11 12 16 13 RCA agreed to supply the video monitor a black and white television with the tuner and speakers removed after others refused because of Tandy s low initial volume of production Tandy used the black and silver colors of the RCA CRT unit s cabinet for the TRS 80 units also 13 Announcement Edit Having spent less than US 150 000 on development Radio Shack announced the TRS 80 Tandy Radio Shack at a New York City press conference on August 3 1977 18 It cost US 399 1784 today or US 599 2679 today with a 12 monitor and a Radio Shack tape recorder the most expensive product Radio Shack previously sold was a US 500 stereo The company hoped that the new computer would help Radio Shack sell higher priced products and improve its schlocky image among customers Small businesses were the primary target market followed by educators then consumers and hobbyists despite its hobbyist customer base Radio Shack saw them as not the mainstream of the business and never our large market 12 19 17 20 21 13 Although the press conference did not receive much media attention because of a terrorist bombing elsewhere in the city the computer received much more publicity at Boston University s Personal Computer Fair two days later 22 21 19 23 24 20 25 26 17 12 6 27 28 excessive citations A front page Associated Press article discussed the novelty of a large consumer electronics company selling a home computer that could do a payroll for up to 15 people in a small business teach children mathematics store your favorite recipes or keep track of an investment portfolio It can also play cards Six sacks of mail arrived at Tandy headquarters asking about the computer over 15 000 people called to purchase a TRS 80 paralyzing the company switchboard and 250 000 joined the waiting list with a 100 deposit 12 6 17 24 25 13 excessive citations Despite the internal skepticism Radio Shack aggressively entered the market The company advertised The 599 personal computer as the most important useful exciting electronic product of our time 29 Kornfeld stated when announcing the TRS 80 This device is inevitably in the future of everyone in the civilized world in some way now and so far as ahead as one can think and Tandy s 1977 annual report called the computer probably the most important product we ve ever built in a company factory Unlike competitor Commodore which had announced the PET several months earlier but had not yet shipped any Tandy had its own factories capable of producing 18 000 computers a month and distribution network and even small towns had Radio Shack stores The company announced plans to be selling by Christmas a range of peripherals and software for the TRS 80 began shipping computers by September opened its first computer only store in October and delivered 5 000 computers to customers by December Still forecasting 3 000 sales a year Radio Shack sold over 10 000 TRS 80s in its first one and a half months of sales 55 000 in its first year and over 200 000 during the product s lifetime 25 11 30 12 16 6 21 15 31 4 19 13 excessive citations one entered the Smithsonian s National Museum of American History 32 By mid 1978 the waits of two months or more for delivery were over 33 and the company could state in advertisements that TRS 80 was on demonstration and available from stock now at every Radio Shack store in this community 29 Byte s 1977 trinity Commodore PET Apple II and TRS 80 Model I Delivery Edit The first units ordered unseen were delivered in November 1977 and rolled out to the stores the third week of December The line won popularity with hobbyists home users and small businesses Tandy Corporation s leading position 34 in what Byte magazine called the 1977 Trinity Apple Computer Commodore and Tandy had much to do with Tandy s retailing the computer through more than 3 000 of its Radio Shack storefronts in the USA 35 Tandy claimed it had 7000 Radio Shack stores in 40 countries 36 The pre release price for the basic system CPU keyboard and video monitor was US 500 and a US 50 deposit was required with a money back guarantee at time of delivery By 1978 Tandy Radio Shack promoted itself as The Biggest Name in Little Computers 37 36 By 1979 1 600 employees built computers in six factories 13 Kilobaud Microcomputing estimated in 1980 that Tandy was selling three times as many computers as Apple Computer with both companies ahead of Commodore 38 By 1981 InfoWorld described Radio Shack as the dominant supplier of small computers 39 Hundreds of small companies produced TRS 80 software and accessories 40 and Adam Osborne described Tandy as the number one microcomputer manufacturer despite having so few roots in microcomputing 41 That year Leininger left his job as director for advanced research French had left to found a software company 42 while Roach became Tandy s CEO Selling computers did not change the company s schlocky image the Radio Shack name embarrassed business customers and Tandy executives disliked the Trash 80 nickname for its products By 1984 computers accounted for 35 of sales however and the company had 500 Tandy Radio Shack Computer Centers 11 16 21 13 43 Model II and III Edit By 1979 when Radio Shack launched the business oriented and incompatible TRS 80 Model II the TRS 80 was officially renamed the TRS 80 Model I to distinguish the two product lines After some exhibitors at the 1979 Northeast Computer Show were forced to clarify that their products bearing the TRS 80 name were not affiliated with Radio Shack publications and advertisers briefly began to use S 80 generically rather than TRS 80 under scare of legal action though this never materialized 44 Following the Model III launch in mid 1980 Tandy stated that the Model I was still sold 45 but it was discontinued by the end of the year Tandy cited one of the main reasons as being the prohibitive cost of redesigning it to meet stricter FCC regulations covering the significant levels of radio frequency interference emitted by the original design 8 7 The Model I radiated so much interference that while playing games an AM radio placed next to the computer could be used to provide sounds 46 Radio Shack offered upgrades double density floppy controller LDOS memory reliable keyboard with numeric keypad lowercase Level II RS 232C as late as 1985 47 Hardware Edit Tandy Radio Shack TRS 80 Model I PCB Tandy Radio Shack TRS 80 Model I Rear Panel Connectors Tandy Radio Shack TRS 80 Model I Level II ROM Upgrade PCB The Model I combines the mainboard and keyboard into one unit which became a design trend in the 8 bit microcomputer era although the Model I has a separate power supply unit It uses a Zilog Z80 processor clocked at 1 78 MHz later models shipped with a Z80A The initial Level I machines shipped in late 1977 early 1978 have only 4 KB of RAM After the Expansion Interface and Level II BASIC were introduced in mid 1978 RAM configurations of 16 KB and up were offered the first 16 KB was in the Model I itself and the remaining RAM in the Expansion Interface The OS ROMs I O area video memory and OS work space occupy the first 16 KB of memory space on the Model I The remaining 48 KB of the 64 KB memory map space is available for program use subject to the amount of physical RAM installed Although the Z80 CPU can use port based I O the Model I s I O is memory mapped aside from the cassette tape and RS 232 serial ports Keyboard Edit Tandy Radio Shack TRS 80 Model I ALPS Keyboard PCB The TRS 80 Model I keyboard uses mechanical switches that suffer from keyboard bounce resulting in multiple letters being typed per keystroke 48 The problem was described in Wayne Green s editorial in the first issue of 80 Micro 49 Dirt cigarette smoke or other contamination enters the unsealed key switches causing electrical noise that the computer detects as multiple presses The key switches can be cleaned but the bounce recurs when the keyboard is reexposed to the contaminating environment 50 Keyboard bounce only occurs in Model I computers with Level II BASIC firmware Level I BASIC has a debounce delay to the keyboard driver to avoid the noisy switch contacts Tandy s KBFIX utility the Model III the last Model I firmware and most third party operating systems also implement the software fix and Tandy changed the keyboard during the Model III s lifetime to an Alps Electric design with sealed switches The Alps keyboard was available as an upgrade for the Model I for 79 50 The keyboard is memory mapped so that certain locations in the processor s memory space correspond to the status of a group of keys Video and audio Edit Layout of characters and pixels on the TRS 80 display 51 The color of the 12 KCS 172 RCA monitor s 13 text is faintly blue the standard P4 phosphor used in black and white televisions Green and amber filters or replacement tubes to reduce eye fatigue were popular aftermarket items Later models came with a green on black display Complaints about the video display quality were common As Green wrote hells bells the monitor is a cheap black and white television set with a bit of conversion for computer use 49 The computer could be purchased without the Radio Shack monitor 25 CPU access to the screen memory causes visible flicker The bus arbitration logic blocks video display refresh video RAM reads during CPU writes to the VRAM causing a short black line This has little effect on normal BASIC programs but fast programs made with assembly language can be affected Software authors worked to minimize the effect and many arcade style games are available for the Tandy TRS 80 Because of bandwidth problems in the interface card that replaced the TV s tuner the display loses horizontal sync if large areas of white are displayed A simple half hour hardware fix corrects the problem The graphics are displayed at a resolution of 64 16 character positions on a screen measuring 7 5 inches 19 cm wide and 6 625 inches 16 83 cm tall 52 Each character is composed of a 2 3 matrix of pixels and corresponds to one byte of the 1 KB video memory used by the TRS 80 In each of those bytes the first six bits control which pixel is displayed The seventh bit is ignored and the eighth toggles graphics mode 51 53 The reason that the seventh bit is ignored is due to the company s decision to have only seven 2102 static RAM chips installed on the computer s motherboard instead of eight to keep the manufacturing cost low 54 Thus there are no lowercase letters in the TRS 80 character set of an unmodified Model I and the number of both graphics symbols and alphanumeric symbols is 64 55 This can be worked around by deleting the unused bit and piggybacking an eighth 2102 chip onto another 56 The alphanumeric symbols are displayed in 5 7 matrices of pixels 51 The 1978 manual for the popular word processor Electric Pencil came with instructions for modifying the computer Although the modification needs to be disabled for Level II BASIC its design became the industry standard and was widely sold in kit form 57 along with an eighth 2102 chip Later models came with the hardware for the lowercase character set to be displayed with descenders With higher density RAM chips and purpose built monitors higher resolution crisp displays are obtainable 80x24 character displays are available in the Model II Model 4 and later systems The Model I has no built in speaker Square wave tones can be produced by outputting data to the cassette port and plugging an amplifier into the cassette Mic line Most games use this ability for sound effects An adapter was available to use Atari joysticks 58 Peripherals EditThis section needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed July 2017 Learn how and when to remove this template message Cassette tape drive Edit User data was originally stored on cassette tape Radio Shack s model CTR 41 cassette recorder was included with the US 599 package 31 3 4 The software based 11 cassette tape interface is slow and erratic 48 Green described it as crummy drives users up the wall and the first issue of 80 Micro has three articles on how to improve cassette performance 49 It is sensitive to audio volume 25 and the computer gives only a crude indication as to whether the correct volume was set via a blinking character on screen while data is loaded To find the correct volume at first use the load is started and the volume is adjusted until the TRS 80 picked up the data Then it is halted to rewind the tape and restart the load Users were instructed to save multiple copies of a software program file especially if audio tape cassettes instead of certified data tape was used Automatic gain control or indicator circuits can be constructed to improve the loading process the owner s manual provides complete circuit diagrams for the whole machine including the peripheral interfaces with notes on operation An alternative to using tape was data transmissions from the BBC s Chip Shop programme in the UK which broadcast software for several different microcomputers over the radio A special program was loaded using the conventional tape interface Then the radio broadcast was connected to the cassette tape interface Tandy eventually replaced the CTR 41 unit with the CTR 80 which had built in AGC circuitry and no volume control This helped the situation but tape operation is still unreliable TRS 80 Model I computers with Level I BASIC read and wrote tapes at 250 baud about 30 bytes per second Level II BASIC doubles this to 500 baud about 60 bytes per second Some programmers wrote machine language programs that increases the speed to up to 2 000 bits per second without a loss of reliability on their tape recorders With the Model III and improved electronics in the cassette interface the standard speed increased to 1 500 baud that works quite reliably on most tape recorders For loading and storing data from tape the CPU creates the sound by switching the output voltage between three states creating crude sine wave audio The first version of the Model I also has a hardware problem that complicated loading programs from cassette recorders Tandy offered a small board which was installed at a service center to correct the issue The ROMs in later models were modified to correct this Model I Expansion Interface Edit Only the Model I uses an Expansion Interface all later models have everything integrated in the same housing The TRS 80 does not use the S 100 bus like other early 8080 and Z80 based computers 12 A proprietary Expansion Interface E I box which fits under the video monitor and served as its base was offered instead Standard features of the E I are a floppy disk controller Centronics parallel port for a printer and added cassette connector Optionally an extra 16 or 32 KB of RAM can be installed and a daughterboard with an RS 232 port 59 The 40 conductor expansion connector passes through to a card edge connector which permits the addition of external peripherals such as an outboard hard disk drive a voice synthesizer or a VOXBOX voice recognition unit 60 61 Originally printing with the Model I requires the Expansion Interface but later Tandy made an alternative parallel printer interface available The Model I Expansion Interface is the most troublesome part of the TRS 80 Model I system It went through several revisions The E I connects to the CPU keyboard with a 6 inch ribbon cable which is unshielded against RF interference and its card edge connector tends to oxidize due to its base metal contacts This demands periodic cleaning with a pencil eraser in order to avoid spontaneous reboots which contributes to its Trash 80 sobriquet Aftermarket connectors plated with gold solves this problem permanently Software developers also responded by devising a recovery method which became a standard feature of many commercial programs They accept an asterisk parameter an asterisk star character typed following the program name when the program is run from the TRSDOS Ready prompt When used following a spontaneous reboot or an accidental reset program crash or exit to TRSDOS without saving data to disk the program loads without initializing its data area s preserving any program data still present from the pre reboot session Thus for example if a VisiCalc user suffers a spontaneous reboot to recover data the user enters V C SPACE at TRSDOS Ready and Visicalc restores the previous computing session intact note 1 The power button on the E I is difficult to operate as it is recessed so as to guard against the user accidentally hitting it and turning it off while in use A pencil eraser or similar object is used to depress the power button and the E I has no power LED making it difficult to determine if it is running or not The expansion unit requires a second power supply identical to the base unit power supply An interior recess holds both supplies The user is instructed to power on and power off all peripherals in proper order to avoid corrupting data or potentially damaging hardware components The manuals for the TRS 80 advise turning on the monitor first then any peripherals attached to the E I if multiple disk drives are attached the last drive on the chain is to be powered on first and work down from there the E I and the computer last When powering down the computer is to be turned off first followed by the monitor E I and peripherals In addition users are instructed to remove all disks from the drives during power up or down or else leave the drive door open to disengage the read write head from the disk This is because a transient electrical surge from the drive s read write head would create a magnetic pulse that could corrupt data This was a common problem on many early floppy drives The E I displays a screen full of garbage characters on power up and unless a bootable system disk is present in Drive 0 it hangs there until the user either presses RESET on the back of the computer which causes it to attempt to boot the disk again or Break Reset was pressed which drops the computer into BASIC Due to the above mentioned problems with potentially corrupting disks it is recommended to power up to the garbage screen with the disk drives empty insert a system disk and then hit RESET InfoWorld compared the cable spaghetti connecting the TRS 80 Model I s various components to the snakes in Raiders of the Lost Ark 48 Radio Shack offered a TRS 80 System Desk 62 that concealed nearly all the cabling It can accommodate the complete computer system plus up to four floppy drives and the Quick Printer Since the cable connecting the Expansion Interface carries the system bus it is short about 6 inches The user has no choice but to place the E I directly behind the computer with the monitor on top This causes problems for a non Tandy monitor whose case did not fit the mounting holes Also the friction fit of the edge connector on the already short interconnect cable makes it possible to disconnect the system bus from the CPU if either unit is bumped during operation Floppy disk drives Edit Radio Shack introduced floppy drives in July 1978 about six months after the Model I went on sale The Model I disk operating system TRSDOS was written by Randy Cook under license from Radio Shack Randy claimed to have been paid 3000 for it The first version released to the public was a buggy v2 0 This was quickly replaced by v2 1 63 Floppy disk operation requires buying the Expansion Interface which included a single density floppy disk interface with a formatted capacity of 85K based on the Western Digital 1771 single density floppy disk controller chip The industry standard Shugart Associates SA 400 minifloppy disk drive was used Four floppy drives can be daisy chained to the Model I The last drive in the chain is supposed to have a termination resistor installed but often it is not needed as it is integrated into later cables 64 Demand for Model I drives greatly exceeded supply at first 49 The drive is unreliable partly since the interface lacked an external data separator buffer 48 The early version s of TRSDOS are also buggy and not helped by the Western Digital FD1771 chip that cannot reliably report its status for several instruction cycles after it receives a command A common method of handling the delay was to issue a command to the 1771 perform several NOP instructions then query the 1771 for the result Early TRSDOS neglects the required yet undocumented wait period and thus false status often returns to the OS generating random errors and crashes Once the 1771 delay was implemented it is fairly reliable In 1981 Steve Ciarcia published in Byte the design for a homemade improved expansion interface with more RAM and a disk controller for the TRS 80 65 A data separator and a double density disk controller based on the WD 1791 chip were made by Percom a Texas peripheral vendor LNW Tandy and others The Percom Doubler adds the ability to boot and use double density floppies using a Percom modified TRSDOS called DoubleDOS The LNDoubler adds the ability to read and write 5 1 4 inch 130 mm diskette drives with up to 720 KB of storage and also the older 8 inch 200 mm diskettes with up to 1 155 KB Near the end of the Model I s lifespan in 1982 upgrades were offered to replace its original controller with a double density one The first disk drives offered on the Model I were Shugart SA 400s which supported 35 tracks and was the sole 5 1 4 inch drive on the market in 1977 78 By 1979 other manufacturers began offering drives Models 3 4 4P uses Tandon TM 100 40 track drives The combination of 40 tracks and double density gives a capacity of 180 kilobytes per single sided floppy disk The use of index sync means that a flippy disk requires a second index hole and write enable notch One could purchase factory made flippies Some software publishers formatted one side for Apple systems and the other for the TRS 80 The usual method of connecting floppy drives involves setting the drive letter via jumper blocks on the drive controller board but Tandy opted for a slightly more user friendly technique where all four select pins on the drives are jumpered and the ribbon cable is missing the Drive Select line Thus the user does not need to worry about moving jumpers around depending on which position on the chain a drive was in A standard flat floppy ribbon cable is usable on the Model I in which case the drives is jumpered to their number on the chain or even an IBM PC twist cable which requires setting each drive number to 1 but only permits two drives on the chain Although third party DOSes allow the user to define virtually any floppy format wanted the lowest common denominator format for TRS 80s is the baseline single density single sided 35 40 track format of the Model I Third party vendors like Aerocomp made available double sided and 80 track 5 1 4 inch and later 3 1 2 inch floppy drives with up to 720 KB of storage each These new drives are half height and therefore require different or modified drive housings Exatron Stringy Floppy Edit An alternative to cassette tape and floppy disk storage from Exatron sold over 4 000 units by 1981 The device is a continuous loop tape drive dubbed the stringy floppy or ESF It requires no Expansion Interface plugging directly into the TRS 80 s 40 pin expansion bus is much less expensive than a floppy drive can read and write random access data like a floppy drive unlike a cassette tape and it transfers data at up to 14 400 baud Exatron tape cartridges store over 64 KB of data The ESF can coexist with the TRS 80 data cassette drive Exatron also made a complementary RAM expansion board that installed in the TRS 80 keyboard to increase memory to 48 KB without the EI 66 Hard drive Edit Radio Shack introduced a 5 MB external hard disk for the TRS 80 Model III 4 in 1983 It is the same hard disk unit offered for the Model II line but came with OS software for Model III 4 An adapter is required to connect it to the Model I s E I 67 The unit is about the same size as a modern desktop computer enclosure Up to four hard disks can be daisychained for 20 MB of storage The LDOS operating system by Logical Systems was bundled which provides utilities for managing the storage space and flexible backup The initial retail price for the first primary unit US 2 495 equivalent to 6 800 in 2021 Later a 15MB hard disk was offered in a white case which can be daisychained for up to 60 MB Like most hard disks used on 8 bit machines there is no provision for subdirectories but the DiskDISK utility is a useful alternative that creates virtual hard disk DSK files that can be mounted as another disk drive and used like a subdirectory would To display the directory contents of an unmounted DiskDISK virtual disk file a shareware DDIR Virtual Disk Directory Utility 68 program was commonly used Printers Edit The Quick Printer 69 is an electrostatic rotary printer that scans the video memory through the bus connector and prints an image of the screen onto aluminum coated paper in about one second However it is incompatible with both the final buffered version of the Expansion Interface and with the heartbeat interrupt used for the real time clock under Disk BASIC This can be overcome by using special cabling and by doing a dummy write to the cassette port while triggering the printer Two third party printers were for 57 mm 2 2 in metal coated paper selling for approximately DM 600 in Germany and a dot matrix printer built by Centronics for normal paper costing at first DM 3000 later sold at approximately DM 1500 in some stores It has only 7 pins so letters with descenders such as lowercase g do not reach under the baseline but are elevated within the normal line Radio Shack offered an extensive line of printers for the TRS 80 family ranging from basic 9 pin dot matrix units to large wide carriage line printers for professional use daisy wheel printers ink jet printers laser printers and color plotters All have a Centronics standard interface and after the introduction of the Color Computer in 1980 many also had a connector for the CoCo s serial interface FP 215 is a flatbed plotter 70 Software EditBASIC Edit Three versions of the BASIC programming language were produced for the Model I Level I BASIC fits in 4 KB of ROM and Level II BASIC fits into 12 KB of ROM Level I is single precision only and had a smaller set of commands Level II introduced double precision floating point support and has a much wider set of commands Level II was further enhanced when a disk system was added allowing for the loading of Disk BASIC 12 Level I BASIC is based on Li Chen Wang s free Tiny BASIC with more functions added by Radio Shack 15 The accompanying User s Manual for Level 1 by David A Lien presents lessons on programming with text and cartoons Lien wrote that it was written specifically for people who don t know anything about computers I want you to have fun with your computer I don t want you to be afraid of it because there is nothing to fear 71 25 Reviewers praised the manual s quality 12 72 73 Level I BASIC has only two string variables A and B 26 numeric variables A Z and one array A Code for functions like SIN COS and TAN is not included in ROM but printed at the end of the book The only error messages are WHAT for syntax errors HOW for arithmetic errors such as division by zero and SORRY for out of memory errors Level I BASIC is not tokenized reserved words are stored literally In order to maximize the code that fits into 4 KB of memory users can enter abbreviations for reserved words For example writing P instead of PRINT saves 3 bytes Level II BASIC introduced in mid 1978 was licensed from Microsoft and is required to use the expansion bus and disk drives Radio Shack always intended for Level I BASIC to be a stopgap until Level II was ready and the first brochure for the Model I in January 1978 mentioned that Level II BASIC was coming soon It is an abridged version of the 16K Extended BASIC since the Model I has 12 KB of ROM space According to Bill Gates It was a sort of intermediate between 8K BASIC and Extended BASIC Some features from Extended BASIC such as descriptive errors and user defined functions were not included but there were double precision variables and the PRINT USING statement that we wanted to get in The entire development of Level II BASIC took about four weeks from start to finish The accompanying manual is more terse and technical than the Level I manual Original Level I BASIC equipped machines could be retrofitted to Level II through a ROM replacement performed by Radio Shack for a fee originally 199 Users with Level I BASIC programs stored on cassette have to convert these to the tokenized Level II BASIC before use A utility for this was provided with the Level II ROMS Disk BASIC allows disk I O and in some cases NewDos 80 MultiDOS DosPlus LDOS adds powerful sorting searching full screen editing and other features Level II BASIC reserves some of these keywords and issues a L3 ERROR suggesting a behind the scenes change of direction intervened between the creation of the Level II ROMs and the introduction of Disk BASIC Microsoft also marketed an enhanced BASIC called Level III BASIC written by Bill Gates 74 on cassette tape The cassette contains a Cassette File version on one side and a disk file version on the second side for disk system users which was to be saved to disk 75 Level III BASIC adds most of the functions in the full 16 KB version of BASIC plus many other TRS 80 specific enhancements Many of Level III BASIC s features are included in the TRS 80 Model III s Level II BASIC and disk BASIC Level I BASIC was still offered on the Model I in either 4K or 16K configurations after the introduction of Level II BASIC Other programming languages Edit Radio Shack published a combined assembler and program editing package called the Series I Assembler Editor 76 80 Micro magazine printed a modification enabling it to run under the Model 4 s TRSDOS Version 6 Also from Radio Shack was Tiny Pascal 77 Microsoft made its Fortran COBOL and BASCOM BASIC compiler available through Radio Shack 76 In 1982 Scientific Time Sharing Corporation published a version of its APL for the TRS 80 Model III as APL PLUS 80 78 Other applications Edit Blackjack and backgammon came with the TRS 80 and at its debut Radio Shack offered four payroll personal finance and educational programs on cassette 12 31 3 13 Its own products quality was often poor 79 A critical 1980 80 Micro review of a text adventure described it as yet another example of Radio Shack s inability to deal with the consumer in a consumer s market The magazine added Sadly too as with some other Radio Shack programs the instructions seem to assume that the reader is either a child or an adult with the mentality of a slightly premature corned beef 80 The more than 2 000 Radio Shack franchise stores as of September 1982 update sold third party hardware and software but the more than 4 300 company owned stores were at first prohibited from reselling or even mentioning products not sold by Radio Shack itself 81 82 83 79 84 13 Green stated in 1980 that although there are more programs for the 80 than for all other systems combined because of the computer s large market share Radio Shack can t advertise this because they are trying as hard as they can to keep this fact a secret from their customers They don t want the TRS 80 buyers to know that there is anything more than their handful of mediocre programs available many of which are disastrous and I m sure doing tremendous damage to the industry 85 86 Broderbund founded that year began by publishing TRS 80 software but by 1983 cofounder Doug Carlston said that the computer turned out to be a terrible market because most of the distribution networks were closed even though there were plenty of machines out there 87 Green wrote in 1982 that Apple had surpassed Tandy in sales and sales outlets despite the thousands of Radio Shack dealers because it supported third party development while we find the Shack seeming to begrudge any sale not made by them and them alone 79 Dealers not affiliated with Radio Shack preferred to sell software for other computers and not compete with the company mail order sales were also difficult because company owned stores did not sell third party publications like 80 Micro 82 13 Charles Tandy reportedly wanted to encourage outside developers but after his death a committee ran the company which refused to help outside developers hoping to monopolize the sale of software and peripherals 13 Leininger reportedly resigned because he disliked the company s bureaucracy after Tandy s death 42 An author wrote in a 1979 article on the computer s mystery of machine language graphics control that Radio Shack seems to hide the neat little jewels of information a hobbyist needs to make a treasure of the TRS 80 He stated that other than the excellent Level I BASIC manual there has been little information until recently TRS 80 owners must be resourceful reporting that the computer s keyboard video and cassette functionality were also undocumented 72 The first book authorized by Tandy with technical information on TRSDOS for the Model I did not appear until after the computer s discontinuation 84 By 1982 the company admitted after no software appeared for the Model 16 after five months that it should have like Apple encouraged third party developers of products like the killer app VisiCalc 88 13 A lengthy 1980 article in a Tandy publication introducing the TRS 80 version of VisiCalc did not mention that the spreadsheet had been available for the Apple II for a year 89 However in the early 1980s it was not uncommon for small companies and municipalities to write custom programs for computers such as the TRS 80 to process a variety of data In one case a small town s vehicle fleet was managed from a single TRS 80 90 By 1985 the company s Ed Juge stated that other than Scripsit and DeskMate we intend to rely mostly on big name market proven software from leading software firms 91 A full suite of office applications became available from the company and others including the VisiCalc and Multiplan spreadsheets and the Lazy Writer Electric Pencil and from Radio Shack itself the Scripsit and SuperScripsit word processors 92 Compared to the contemporary Commodore and Apple micros the TRS 80 s block graphics and crude sound were widely considered limited The faster speed available to the game programmer not having to processor color data in high resolution went a long way to compensating for this TRS 80 arcade games tended to be faster with effects that emphasized motion This perceived disadvantage did not deter independent software companies such as Big Five Software from producing unlicensed versions of arcade games like Namco s Galaxian Atari s Asteroids 93 Taito s Lunar Rescue Williams s Make Trax 94 and Exidy s Targ 58 and Venture Sega s Frogger and Zaxxon were ported to the computer and marketed by Radio Shack 95 94 Namco Midway s Pac Man was cloned by Philip Oliver and distributed by Cornsoft Group as Scarfman 94 96 Atari s Battlezone was cloned for the Models I III by Wayne Westmoreland and Terry Gilman and published by Adventure International as Armored Patrol 97 They also cloned Eliminator based on Defender and Donkey Kong 98 the latter wasn t published until after the TRS 80 was discontinued because Nintendo refused to license the game 94 Some games originally written for other computers were ported to the TRS 80 Microchess has three levels of play and can run in the 4 KB of memory that is standard with the Model I the classic ELIZA is another TRS 80 port Both were offered by Radio Shack 94 99 Apple Panic itself a clone of Universal s Space Panic was written for the TRS 80 by Yves Lempereur and published by Funsoft 100 Epyx s Temple of Apshai runs slowly on the TRS 80 94 Infocom ported its series of interactive text based adventure games to the Models I III the first Zork I was marketed by Radio Shack 95 94 Adventure International s text adventures began on the TRS 80 94 as did Sea Dragon by Westmoreland and Gilman later ported to the other home micros citation needed Android Nim by Leo Christopherson was rewritten for the Commodore PET and Apple citation needed Many games are unique to the TRS 80 including Duel N Droids 101 also by Christopherson an early first person shooter 13 Ghosts by Software Affair the Orchestra 80 85 and 90 people 102 103 104 and shooters like Cosmic Fighter and Defence Command citation needed and strange experimental programs such as Christopherson s Dancing Demon 94 105 in which the player composes a song for a devil and choreographs his dance steps to the music 106 Radio Shack offered simple graphics animation programs Micro Movie and Micro Marquee and Micro Music 99 Radio Shack offered a number of programming utilities including an advanced debugger a subroutine package and a cross reference builder 107 Probably the most popular utility package was Super Utility written by Kim Watt of Breeze Computing 108 Other utility software such as Stewart Software s Toolkit offered the first sorted directory decoding or reset of passwords and the ability to eliminate parts of TRSDOS that were not needed in order to free up floppy disk space They also produced the On Line 80 BBS a TRSDOS based Bulletin Board System Misosys Inc was a prolific producer of sophisticated TRS 80 utility and language software for all models of TRS 80 from the very beginning 109 Perhaps because of the lack of information on TRSDOS 84 and its bugs 13 by 1982 perhaps more operating systems existed for the TRS 80 than for any other computer 110 TRSDOS is limited in its capabilities since like Apple DOS 3 3 on the Apple II it is mainly conceived of as a way of extending BASIC to support disk drives Numerous alternative DOSes appeared the most prominent being LDOS because Radio Shack licensed it from Logical Systems and adopted it as its official DOS for its Models I and III hard disk drive products Other alternative TRS 80 DOSes included NewDOS from Apparat Personal Computers and DoubleDOS DOSPlus MicroDOS UltraDOS later called Multidos The DOS for the Model 4 line was originally called TRSDOS Version 6 but was actually produced by and licensed from Logical Systems and is technically a descendant of the original Model I LDOS The memory map of the Model I and III render them incompatible with the standard CP M OS for Z80 business computers which loads at hexadecimal address 0000 with TPA Transient Program Area starting at 0100 the TRS 80 ROM resides in this address space Omikron Systems Mappers board remaps the ROM to run unmodified CP M programs on the Model I A customized version of CP M is available but loses its portability advantage 111 112 80 Micro magazine published a do it yourself CP M modification for the Model III 113 Reception EditDan Fylstra among the first owners wrote in Byte in April 1978 that as an appliance computer the TRS 80 brings the personal computer a good deal closer to the average customer suitable for home and light business use He concluded that it is not the only alternative for the aspiring personal computer user but it is a strong contender 25 Jerry Pournelle wrote in 1980 that the basic TRS 80 is a lot of computer for the money He criticized the quality of Tandy s application and system software and high cost of peripherals Pournelle reported however that with the Omikron board a customer paid less than 5000 for a computer compatible with TRS 80 and CP M software all without building a single kit 111 Three years later Pournelle was less positive about the computer He wrote in May 1983 As to our TRS 80 Model I we trashed that sucker long ago It was always unreliable and repeated trips to the local Radio Shack outlet didn t help The problem was that Tandy cut corners 114 Pournelle wrote in July 1983 84 I m a little bitter about my experiences with Tandy I had genuinely thought that the Model I was the machine of the future an inexpensive home computer that could be expanded by stages until it would do professional work Of course it was never that First Tandy tried to fence in Model I users through that goofy operating system and then it wouldn t let Radio Shack stores sell non Tandy software It had never been all that well designed and when sales took off much faster than anticipated the quality control system couldn t cope Compatible successors EditFor computers using the TRS 80 name but unrelated to Models I III and 4 see List of TRS 80 and Tandy branded computers Tandy replaced the Model I with the broadly compatible Model III in 1980 The TRS 80 Model II is an entirely different and incompatible design Model III Edit TRS 80 Model III ManufacturerTandy CorporationTypeHome and small business computerRelease dateJuly 1980 42 years ago 1980 07 Introductory price 699 4KB RAM Level I 999 16K Level II 2495 48K two 180 KB floppy drives RS 232C 115 DiscontinuedSeptember 1983 39 years ago 1983 09 Operating systemTRSDOS 1 3 LDOS 5 116 CPUZilog Z80A 2 MHzMemory4 KB or 16 32 or 48 KBDisplay16 rows by 64 or 32 columns block graphicsGraphicsoptional 512 by 192 pixels 369 extra 117 Soundoutput through cassette portBackwardcompatibilityModel I Z80 code 80 higher with patches BASIC 100 PredecessorModel ISuccessorModel 4Tandy released the TRS 80 Model III on July 26 1980 The improvements of the Model III over the Model I include 118 built in lowercase a better keyboard with repeating keys an enhanced character set a real time clock 1500 baud cassette interface a faster 2 03 MHz Z80 processor and an all in one enclosure requiring fewer cables A Model III with two floppy drives requires the use of only one electrical outlet a two drive Model I requires five outlets note 2 The Model III avoids the complicated power on off sequence of the Model I Shortly after the Model III s introduction Model I production was discontinued as it did not comply with new FCC regulations as of January 1 1981 regarding electromagnetic interference 30 48 119 7 13 Tandy distinguished between the high end Model II 20 and Model III describing the former as an administrative system good for things like word processing data management and VisiCalc operations and suitable for small businesses 120 The lowest priced version of the Model III was sold with 4 KB of RAM and cassette storage The computer s CPU board has three banks of sockets 8 sockets to a bank which take type 4116 DRAMs so memory configurations come in 16 KB 32 KB or 48 KB RAM memory sizes Computers with 32 KB or 48 KB RAM can be upgraded with floppy disk drive storage There is space inside the computer cabinet for two full height drives Those offered by Tandy Radio Shack are single sided 40 track double density MFM encoding for 180K of storage Third party suppliers offered double sided and 80 track drives though to control them they had to modify the TRSDOS driver code or else furnish an alternative third party DOS which could see below The installation of floppy disk drives also requires the computer s power supply to be upgraded There is no internal cooling fan in the Model III it uses passive convection cooling unless an unusual number of power hungry expansions were installed internally such as a hard disk drive graphics board speedup kit RS 232 board etc Tandy claimed that the Model III was compatible with 80 of Model I software 120 Many software publishers issued patches to permit their Model I programs to run on the Model III Marketing director Ed Juge explained that their designers considered changing from the Model I s 64 column by 16 row video screen layout but that they ultimately decided that maintaining compatibility was most important 121 The Model III s memory map and system architecture is mostly the same as the Model I but the disk drives and printer port were moved from memory mapped to port I O thus Model I software that attempts to manipulate the disk controller directly or output to the printer in particular Model I DOSes and application packages such as Visicalc and Scripsit will not work Under the supplied TRSDOS 1 3 operating system Model I disks can be read in the Model III but not vice versa 30 The optional LDOS OS by Logical Systems Inc use a common disk format for both Model I and Model III versions Customers and developers complained of bugs in the Model III s Microsoft BASIC interpreter and TRSDOS 120 Tandy Radio Shack and TRS 80 magazines like 80 Micro periodically published many software patches to correct these deficiencies and to permit users to customize the software to their preferences Differences in the WD1771 and WD1791 floppy controllers created problems reading Model I disks on a Model III the double density upgrade in the Model I include both chips while a Model III had only the WD1791 The WD1771 supports four data markers while the WD1791 only supports two and some versions of TRSDOS for the Model I also use them In addition they are used by copy protection schemes Software was available to allow Model I disks to be read on a Model III The WD1791 supports the 500 bit s bitrate needed for high density floppy drives but the controller is not capable of using them without extensive modifications TRSDOS for the Model III was developed in house by Radio Shack rather than being contracted out like the Model I s DOS None of the code base from Model I DOS was reused and the Model III DOS was rewritten from scratch this also created some compatibility issues since the Model III DOS s API was not entirely identical to the Model I DOS This was primarily to avoid legal disputes with Randy Cook over ownership of the code as had occurred with Model I DOS and also because Radio Shack originally planned several features for the Model III such as 80 column text support that were not included Two early versions 1 1 and 1 2 were replaced by version 1 3 in 1981 which became the standard Model III OS TRSDOS 1 3 is not format compatible with 1 1 and 1 2 a utility called XFERSYS is provided which converted older format disks to TRSDOS 1 3 format this change is permanent and the resultant disks cannot be read with the older DOS versions The Model III s boot screen was cleaned up from the Model I Instead of displaying garbage on screen at power up it displays a Diskette prompt if a bootable floppy is not detected The user can insert a disk and press any key to boot On powerup or reset holding down the Break key will boot the computer into ROM based Level II BASIC This ability is useful if the disk drive is not functioning and cannot boot a TRSDOS disk or if a boot disk is not available it permits an operator familiar with the machine hardware to perform diagnostics using BASIC s PEEK and POKE commands This works for the Model 4 as well but not for the 4P While Model I DOS is fairly flexible in its capabilities Model III DOS is hard coded to only support 180K single sided floppies a problem fixed by the many third party DOSes To that end when Radio Shack introduced hard disks for the TRS 80 line in 1982 the company licensed LDOS rather than attempt to modify Model III DOS for hard disk support Level II BASIC on the Model III is 16 KB in size and incorporates a few features from Level I Disk BASIC TRSDOS 1 3 was given a few more minor updates the last being in 1984 although the version number was unchanged This includes at least one update that writes an Easter Egg message Joe you rummy buzzard on an unused disk sector which is reputedly a joke message left by a programmer in a beta version but accidentally included in the production master 122 The Model III keyboard lacks CONTROL Many application programs use while others use Shift Often CLEAR is used in combination with number and alpha keys The Model III keyboard also lacks Caps Lock to caps lock the alpha keys the user presses Shift 0 Under LDOS typeahead is supported Because TRSDOS 1 3 was found wanting by many users Tandy offered at added cost Logical System s LDOS Version 5 as an alternative As with the Model I other third party sources also offered TRSDOS alternatives for the Model III including NewDOS Alphabit s MultiDOS and Micro Systems Software s DOSPlus These are compatible with TRSDOS 1 3 and ran the same applications programs but offer improved command structures more and better system utilities and enhancements to the Microsoft BASIC interpreter After writing the original Model I TRSDOS Randy Cook began work on his own DOS titled VTOS which was superseded by LDOS and also created some frustration for users as it is the only TRS 80 DOS to be copy protected Although mostly intended as a disk based computer the Model III was available in a base cassette configuration with no disk hardware and only 16 KB of RAM with Level II BASIC Radio Shack also offered a 4K version with Level I BASIC identical to Model I Level I BASIC but with the addition of LPRINT and LLIST commands for printer output Upgrading to a disk machine necessitate installing at least 32 KB of RAM the disk controller board and another power supply for the disk drives Disk upgrades purchased from Radio Shack included TRSDOS 1 3 users upgrading from third party vendors had to purchase DOS separately most opted for LDOS or DOSPlus though a great many Model III applications programs included a licensed copy of TRSDOS 1 3 As with the Model I s E I the RS 232C port on the Model III was an extra cost option and not included in the base price of the computer though the dual disk Model III for 2495 included the serial port Like the Model I the Model III sold well in the educational market Many school administrators valued the Model III s all in one hardware design because it made it more difficult for students to steal components 13 InfoWorld approved of the Model III s single unit design simplified cable management and improvements such as lack of keyboard bounce and improved disk reliability The reviewer a former Model I owner stated I m impressed and that had the Model III been available it s probable that I wouldn t have sold it He concluded If you re looking for a computer that s not too expensive but that performs well you would be wise to test the Model III you might end up buying it 48 Don French who had left Radio Shack to found FMG Software after designing the Model I expressed his disappointment in the new machine while trying to convert CP M to run on it I ve encountered numerous problems with the floppy drive and its interface Radio Shack will sell a Model III to anyone They re trying to market it as a business computer when the existing software is woefully inadequate 48K just isn t enough You run out of memory before you get going They re selling a medical package that takes up nine disks I think the Model III is a very poorly conceived machine 120 Aftermarket products Edit Aftermarket hardware were offered by Tandy Radio Shack and many third party manufacturers The usual selection of add ons and peripherals available for the Model I were offered outboard floppy drives one or two could be plugged into a card edge connector on the back panel an outboard hard disk drive LDOS was furnished as Tandy s hard drive OS vice TRSDOS a high resolution graphics board 123 resolution 512 by 192 pixels note 3 an RS 232C serial port on an internal circuit card and a parallel printer connected by a card edge connector A popular hardware software add on was the Orchestra 90 124 125 126 music synthesizer It can be programmed to play up to five voices with a range of six octaves stereophonically A great many Orch 90 as it was often called music files were available for download from CompuServe The Orch 90 was licensed from a company called Software Affair which also produced the Model I compatible Orchestra 85 from 1981 At least three vendors produced CP M modifications for the Model III Omikron also a Model I mod Holmes Engineering and Memory Merchant 127 Options were available for upgrading the CRT to the CP M professional standard of 80 columns and 24 rows as well as eight inch floppy drives A number of third party manufacturers specialized in upgrading Model IIIs with high performance hardware and software and remarketing them under their own labels 128 note 4 The improvements typically included internal hard disk drives greater capacity floppy drives 4 MHz Z80 speedup kits professional grade green or amber CRT video displays better DOS software typically DOSPlus by Micro Systems Software or LDOS by Logical Systems including the all important hard drive backup utilities and custom menu driven shell interfaces which insulated non expert users business employees from the DOS command line These were touted as high productivity turnkey systems for small businesses at less cost than competing business systems from higher end providers such as IBM and DEC as well as Radio Shack s own TRS 80 Model II Model 4 Edit Main article TRS 80 Model 4 TRS 80 Model 4 standard version TRS 80 Model 4P The successor to the Model III is the TRS 80 Model 4 released in April 1983 It has faster Z80A 4 MHz CPU 129 a larger video display 80 columns x 24 rows with reverse video bigger keyboard internal speaker and its 64 KB of RAM can be upgraded to 128 KB of bank switched RAM The display can be upgraded with a high resolution graphics card yielding 640 240 pixels The Model 4 is fully compatible with Model III and CP M application software A diskless Model 4 with 16 KB RAM and Level II BASIC cost 999 with 64 KB RAM and one single sided 180K disk drive 1 699 and two drives with RS 232C 1 999 an upgrade for Model III owners cost 799 and provided a new motherboard and keyboard 73 Tandy sold 71 000 in 1984 130 The Model 4 includes all of the Model III s hardware port assignments and operating modes making it 100 compatible Model III programs running on a Model 4 can access the Model 4 s added hardware features like 4 MHz clock rate bigger video screen and keyboard banked RAM above 64 KB There were aftermarket software packages that made this ability available to non programmer users 131 132 The Model 4P is a transportable version introduced in September 1983 and discontinued in early 1985 It is functionally the same as the dual drive desktop model but lacks the card edge connector for two outboard diskette drives and for cassette tape interface It has a slot for an internal modem card and could emulate a Model III The Model 4D with bundled Deskmate productivity suite was introduced in early 1985 It has a revised CPU board using faster gate array logic which includes the floppy controller and RS 232C circuitry all on a single board The computer has two internal double sided diskette drives and is the last model descended from the 1977 Model I It retailed for 1 199 at its introduction in 1985 During 1987 1988 the retail stores removed the Model 4Ds from display but they were available by special order through 1991 DGT 100 by DIGITUS Ind Com Serv de Eletronica Ltda one of a dozen brands of TRS 80 clones made by other companies See also EditList of TRS 80 games List of TRS 80 software List of TRS 80 clones SoftSide magazine with BASIC programs for the TRS 80 and other microcomputers The Alternate Source Programmer s Journal TRS 80 magazine with technical programming articlesNote Edit The user must take care not to do anything that could cause memory to be overwritten they should recover immediately without running any other programs Since programs may start automatically via the TRSDOS AUTO command during a spontaneous reboot they take the precaution of holding down Enter to prevent this from happening It takes TRSDOS some half dozen seconds to load from floppy disk the user has this long to keep an AUTO d program from loading This star parameter became a standard for many software applications running on the Models III and 4 for instance LS DOS s TED and Prosoft s Allwrite One outlet each for the CPU keyboard Expansion Interface Video Monitor and the drives The Radio Shack catalog entry advertises 640x240 resolution but this is a misprint It was necessary to rebrand these highly modified Model IIIs because Radio Shack enforced a strict policy that no repair service would be performed on nonstandard RS products References Edit a b Forster Winnie 2005 The encyclopedia of consoles handhelds amp home computers 1972 2005 Gameplan p 17 ISBN 3 00 015359 4 Advertisement Radio Shack Computerworld October 15 1979 How we sold over 100 000 TRS 80 Model I Systems Table 2 United States 1978 1982 Computers and People Berkeley Enterprises 33 36 19 1984 TRS 80 all models 2 400 000 a b McCracken Harry August 3 2012 Please Don t Call It Trash 80 A 35th Anniversary Salute to Radio Shack s TRS 80 Time Mooallem Jon April 19 2010 The Lost Tribes of RadioShack Tinkerers Search for New Spiritual Home Wired Retrieved August 3 2012 a b c d e Welch David and Theresa 2007 Priming the Pump How TRS 80 Enthusiasts Helped Spark the PC Revolution Ferndale Michigan The Seeker Books ISBN 978 0 9793468 0 4 a b c TRS 80 Microcomputer News January 1981 Retrieved March 7 2015 In November we announced that manufacturing of the Model I computer would stop prior to the end of 1980 primarily because to meet the new FCC regulations we would have had to redesign the entire product case and all which would have made the cost of the Model I as much as the Model III a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help a b Radio Shack TRS 80 Micro Computer System oldcomputer org Retrieved May 6 2010 obituary John Roach Pioneer of the Personal Computer Is Dead at 83 The New York Ledger Business March 24 2022 Texas Christian University John V Roach Honors College Archived from the original on 2018 05 27 Retrieved 2018 05 26 a b c d e Swaine Michael August 31 1981 How the TRS 80 Was Born InfoWorld Vol 3 no 17 pp 40 43 Retrieved February 28 2011 a b c d e f g h i j Thomas Wes September October 1977 Radio Shack s 600 Home Computer Creative Computing pp 94 95 a b c d e f g h i j k l m n o p q r s t White Ron August 1987 The Tandy Story It all started 10 years ago in a converted used car showroom 80 Micro pp 50 64 Retrieved May 18 2019 a b c Reed Matthew The Introduction of the TRS 80 Part 1 TRS 80 org Retrieved January 23 2015 a b c Leininger Steven W September 1977 TRS 80 architect reminisces about design project San Diego Computer Society Archived from the original on May 31 2012 Retrieved February 28 2011 a b c d Ahl David November 1984 Tandy Radio Shack enters the magic world of computers Creative Computing p 292 Retrieved February 26 2011 a b c d Reed Matthew The Introduction of the TRS 80 Part 2 TRS 80 org Retrieved January 23 2015 Rothman Lile The Personal Computer That Beat Apple For a While Time Archived from the original on August 3 2015 a b c Brown Chris January 1980 The Tandy Story 80 Microcomputing pp 28 30 Retrieved October 17 2013 a b c Freiberger Paul August 31 1981 Radio Shack Prepares for the Future InfoWorld Vol 3 no 17 pp 51 53 54 Retrieved October 26 2016 a b c d Bartimo Jim August 20 1984 Radio Shack Polishes Its Image InfoWorld Vol 6 no 34 pp 47 52 Retrieved February 28 2011 Computer fair comes to Boston Personal Computing Magazine May 1 1977 Retrieved March 7 2021 If you are going to be anywhere all the computer buffs from near Boston on August 4th 5th or 6th you may want to get over to Boston University They are going to have a PERSONAL COMPUTING show complete with exhibits seminars and everything that s new and up to date that you can see touch feel and play with in home computing And just because Boston suburbia has more colleges and universities per square foot than any other region of the United States doesn t mean that this computing show is just for high school college students and their professors To be sure MIT Tufts Harvard Boston College Brandeis Emerson Simmons Northeastern Babson University of Massachusetts Bentley Wentworth Lincoln Emmanuel Lesley Curry Radcliff Jackson Suffolk Wheelock and so forth will be there B U is organizing the fair to be of interest for everybody in personal computing Clinton Pardons Terror The New York Post 1999 08 13 Retrieved 2017 08 03 a b Computers May Soon Be In Homes Lakeland Ledger Associated Press August 6 1977 pp 1A Retrieved January 23 2015 a b c d e f g Fylstra Dan April 1978 The Radio Shack TRS 80 An Owner s Report Byte Vol 3 no 4 p 49 Retrieved October 17 2013 Perez Gina M 2005 Fuerzas Armadas de Liberacion Nacional FALN Encyclopedia of Chicago Chicago Historical Society Blast from the Computer s Past World Technology Computer Repair and Service World Technology LLC August 3 2017 Retrieved March 7 2021 Introduction of the TRS 80 at the Boston Personal Computer Faire in 1977 Photo Lawrence Hageman Forums Retrieved March 7 2021 a b To the Doctor the Lawyer the Butcher the Baker the Candlestick Maker and Everyone Else The Galveston Daily News advertisement May 26 1978 pp 3 A Retrieved October 6 2015 a b c Hogan Thom August 31 1981 A Look at Radio Shack s Five Computers InfoWorld Vol 3 no 17 pp 44 45 Retrieved February 28 2011 a b c 1977 TRS 80 Radio Shack Introduction Brochure Radio Shack 1977 Archived from the original on July 15 2011 Retrieved March 14 2011 Righthand Jess August 3 2010 August 3 1977 The TRS 80 Personal Computer Goes on Sale Smithsonian Retrieved January 23 2015 Baker Joe April 28 1978 Microcomputer stirs interest The San Bernardino County Sun pp B 19 Retrieved October 6 2015 TRS 80 Microcomputer System Model I 16k Level II Computer Computing History www computinghistory org uk Most Important Companies Byte September 1995 Archived from the original on June 18 2008 Retrieved June 10 2008 a b Radio Shack Computer Catalog RSC 3 page 24 Radio Shack Catalogs dot com Tandy Radio Shack Archived from the original on May 31 2017 Retrieved December 1 2022 Radio Shack Computer Catalog RSC 2 page 20 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 Green Wayne October 1980 Publisher s Remarks Kilobaud Microcomputing pp 6 9 Retrieved June 23 2014 Hogan Thom August 31 1981 From Zero to a Billion in Five Years InfoWorld Vol 3 no 17 pp 6 7 Retrieved February 15 2015 Lundell Allan August 31 1981 TRS 80 Outcrop Companies Evolve InfoWorld Vol 3 no 17 pp 46 47 Retrieved February 15 2015 Osborne Adam April 13 1981 The Portable Osborne InfoWorld Vol 3 no 17 pp 42 43 Retrieved January 1 2015 a b Markoff John October 5 1981 TRS 80 Co creator to Leave Tandy InfoWorld Vol 3 no 20 pp 1 6 Retrieved March 20 2020 John Roach Tandy Radio Shack Consumer Electronics Association Archived from the original on July 9 2007 Retrieved February 26 2011 Reed Matthew What does S 80 mean Retrieved February 26 2020 TRS 80 Microcomputer News September 1980 Retrieved March 7 2015 First of all the Model I is not dropped it is in the 1981 Radio Shack Annual catalog and the price is unchanged a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help John Freire audio interview discussing the use of an AM radio for game sounds on the Model I digibarn com Retrieved July 20 2010 1984 Radio Shack Computer Catalog RSC 10 page 27 radioshackcatalogs dot com Tandy Radio Shack Retrieved November 30 2022 a b c d e f Hogan Thom August 31 1981 The Radio Shack TRS 80 Model III Computer InfoWorld Vol 3 no 17 pp 35 37 Retrieved February 28 2011 a b c d Green Wayne January 1980 Where We re Coming From Where We re Bound 80 Micro p 8 Retrieved October 17 2013 a b Reed Matthew Model I Keybounce TRS 80 org Retrieved May 20 2019 a b c Barden William Jr June 1980 The Assembly Line 80 Micro pp 22 24 Retrieved October 14 2021 Mazur 1983 p 386 Mazur 1983 p 294 297 Technical Reference Handbook 1982 pp 34 96 97 Mazur 1983 pp 258 259 Mazur 1983 pp 28 313 314 Reed Matthew The Electric Pencil Lower Case Modification Retrieved February 27 2016 a b Williams Gregg September 1981 Big Five Software Byte Vol 6 no 9 pp 384 386 Retrieved October 19 2013 1978 Radio Shack Tandy TRS 80 Computer Catalog RSC 02 Radio Shack 1978 Radio Shack Computer Catalog RSC 3 page 10 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 Radio Shack Computer Catalog RSC 2 page 13 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 Radio Shack Computer Catalog RSC 2 page 19 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved November 30 2022 Radio Shack Computer Catalog RSC 2 page 15 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 2 2022 Radio Shack Computer Catalog RSC 2 page 14 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 Ciarcia Steve February 1982 Build the Disk 80 Memory Expansion and Floppy Disk Control Byte Vol 6 no 3 p 36 Retrieved October 18 2013 Lundell Allan August 31 1981 Stringy Floppy from Exatron InfoWorld Vol 3 no 17 pp 47 48 Retrieved February 15 2015 Radio Shack Computer Catalog RSC 8 page 52 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 McKay Bryan January 2 1986 DDIR read me p 1 Radio Shack Computer Catalog RSC 2 page 16 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 GitHub human39 fp 215 plotter Radio Shack TRS 80 FP 215 Flatbed Plotter Info August 11 2019 via GitHub Lien David A 1978 User s Manual for Level 1 p 1 a b Yeager George H August 1979 Exploring TRS 80 Graphics Byte Vol 4 no 8 pp 82 84 a b Archer Rowland Jr October 1983 Radio Shack s TRS 80 Model 4 Byte Vol 8 no 10 pp 292 302 Retrieved January 31 2015 Program Instructions for Level III BASIC Microsoft Consumer Products 1979 p 1 Program Instructions for Level III BASIC Microsoft Consumer Products 1979 p 11 a b 1982 Radio Shack Computer Catalog RSC 6 page 11 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 1 2022 1982 Radio Shack Computer Catalog RSC 6 page 9 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved May 1 2019 Gates Phelps March 1983 A microcomputer APL PLUS system implementation ACM SIGAPL APL Quote Quad 13 3 201 204 doi 10 1145 390005 801217 a b c Green Wayne December 1982 Is the Shack in real trouble 80 Micro editorial pp 8 10 12 Retrieved February 29 2020 O Brien William August 1980 Pyramid 80 Micro No 8 p 21 Retrieved February 12 2015 Shuford Dan B February 1980 The Bottom Shelf Software For All Seasons 80 Micro No 2 pp 36 37 Retrieved October 17 2013 a b Green Wayne August 1981 Tandy Growth Retarded 80 Micro No 20 p 10 Retrieved May 28 2019 Shea Tom September 13 1982 All others sell at list price we deal InfoWorld Vol 4 no 36 p 11 Retrieved March 17 2019 a b c d Pournelle Jerry July 1983 Interstellar Drives Osborne Accessories DEDICATE 32 and Death Valley Byte Vol 8 no 7 p 323 Retrieved August 28 2016 Green Wayne August 1980 80 Remarks 80 Micro No 8 p 8 Retrieved February 12 2015 Green Wayne November 1980 Publisher s Remarks Kilobaud pp 6 8 ISSN 0192 4575 Retrieved June 23 2014 Barry David October 1983 Profiles The Carlston Trio Antic Retrieved July 1 2021 Markoff John July 5 1982 Radio Shack set apart from the rest of the field InfoWorld Vol 4 no 26 p 36 Retrieved February 10 2015 Reed Matthew VisiCalc TRS 80 org Retrieved January 23 2015 Clack Jeff April 1 1983 Vehicle Maintenance How the City of Lander WY keeps tracke on their Model III 80 U S 80 Northwest Publishing Retrieved October 9 2019 Juge Ed October 1985 News for the top what s really going on at Tandy Creative Computing p 108 Retrieved October 14 2016 1982 Radio Shack Computer Catalog RSC 6 page 10 Radio Shack Catalogs dot com Tandy Radio Shack Retrieved December 2 2022 Super Nova TRS 80 dot org Matthew Reed Retrieved December 1 2022 a b c d e f g h i Dobson Dale November 26 2012 Games from the Trash The History of the TRS 80 Gamasutra Retrieved May 13 2019 a b Radio Shack Computer Catalog RSC 12 page 31 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Software Category page 4 Scarfman TRS 80 dot org Matthew Reed Retrieved May 8 2019 Armored Patrol TRS 80 dot org Matthew Reed Retrieved May 7 2019 Search Results for eliminator Donkey Kong TRS 80 dot org Matthew Reed Retrieved May 8 2019 a b 1982 Radio Shack Computer Catalog RSC 6 page 8 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Software Category page 5 Apple Panic TRS 80 dot org Matthew Reed Retrieved May 8 2019 Duel N Droids videogamegeek dot com BoardGameGeek LLC Retrieved May 14 2019 Mitchell Robert November 1984 Ghost Busting 80 Micro CW Communications p 192 Retrieved July 15 2020 13 Ghosts TRS 80 mobygames dot com Blue Flame Labs Retrieved May 14 2019 1985 Radio Shack Computer Catalog RSC 14 page 36 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Dancing Demon www dnull com Cooper Elizabeth Kolya Yvon May 1981 Dancing Demon from Radio Shack Byte Vol 6 no 5 p 148 Retrieved October 18 2013 Radio Shack Computer Catalog RSC 7 page 9 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Super Utility TRS 80 dot org Matthew Reed Retrieved May 7 2019 Misosys 1992 Catalog page 1 PDF tim mann dot org Roy Soltoff Misosys Inc Retrieved May 8 2019 Archer Rowland Jr December 1982 Multidos A New TRS 80 Disk Operating System Byte Vol 7 no 12 pp 392 397 Retrieved February 6 2015 a b Pournelle Jerry July 1980 Omikron TRS 80 Boards NEWDOS and Sundry Other Matters Byte Vol 5 no 7 p 198 Retrieved October 18 2013 Theresa Welsh David Welsh Priming the Pump How TRS 80 Enthusiasts Helped Spark the PC Revolution The Seeker Books 2007 ISBN 0979346819 Chapter 2 The DOS Wars Brewer Bill March 1983 CP M Cheap 80 Micro CW Communications pp 112 122 Retrieved July 19 2020 Pournelle Jerry May 1983 Ulterior Motives Lobo Buying Your First Computer JRT Update Byte Vol 8 no 5 pp 298 324 1981 Radio Shack Computer Catalog RSC 4 pages 5 6 radioshackcatalogs dot com Tandy Radio Shack Retrieved May 21 2019 Radio Shack Computer Catalog RSC 8 page 40 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Radio Shack Computer Catalog RSC 8 page 52 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 1981 Radio Shack Computer Catalog RSC 4 pg 5 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Robertson Nancy December 1980 Model I Caught By FCC Fallout 80 Micro No 12 pp 51 56 Retrieved March 21 2011 a b c d Freiberger Paul August 31 1981 Bugs in Radio Shack TRS 80 Model III How Bad Are They InfoWorld Vol 3 no 17 p 49 Retrieved February 28 2011 Juge Ed September 1980 Inside 80 80 Micro No 9 CW Communications pp 10 11 Retrieved May 22 2019 The TRSDOS rummy buzzard release www trs 80 org 1983 Radio Shack Computer Catalog RSC 8 page 52 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Orchestra 90 trs80 dot org Matthew Reed Retrieved May 3 2017 1985 Radio Shack Computer Catalog RSC 12 page 31 radioshackcatalogs dot com Tandy Radio Shack Retrieved December 2 2022 Ludwig Gary A March 1985 Let There Be Music 80 Micro CW Communications p 114 Retrieved July 9 2020 Kepner Terry December 1983 CP M III Ways 80 Micro CW Communications p 122 Retrieved July 17 2020 The Muscle Micros These Three Sleek Supercharged Model IIIs 80 Micro April 1983 pp 81 94 Retrieved May 22 2019 TRS 80 Computers TRS 80 Model 4 Trs 80 com March 4 2009 Retrieved August 13 2013 Bartimo Jim March 11 1985 Tandy Revamps Product Line InfoWorld Vol 7 no 10 pp 28 29 Retrieved January 21 2015 Soltoff Roy The Misosys Quarterly Vol I iii pg 6 LDOS 5 3 Model 4 Hardware Interface Kit PDF tim mann dot org Misosys Inc Retrieved November 12 2019 Dalton David September 1985 The Enhancer 80 Micro product review CW Communications p 33 Retrieved November 12 2019 Further reading EditTRS 80 Micro Computer Technical Reference Handbook 2nd ed Radio Shack 1982 Retrieved October 14 2021 Mazur Ken 1983 The Creative TRS 80 Creative Computing Press ISBN 9780916688363 Retrieved October 14 2021 External links Edit Wikimedia Commons has media related to TRS 80 Models I III and 4 TRS 80 at Curlie Radio Shack Catalog Archive 1939 2011 Radio Shack Model I and II catalog RSC 3 trs 80 com Ira Goldklang s TRS 80 Revived Site TRS 80 Model 1 at www old computers com REM 80 The North West TRS 80 USers Group Magazines TRS 80 Emulator in Javascript online emulation of Model III BASIC amp commercial arcade games jTandy another javascript TRS 80 emulator online emulation of Model III BASIC amp commercial arcade games Tandy Model 4 4P Technical Reference LDOS 5 1 User Manual Byte magazine review of LDOS 5 1 Guide to the Radio Shack collection Computer History Museum Online Archive of California California Digital Library 2004 Retrieved from https en wikipedia org w index php title TRS 80 amp oldid 1128348890 modeliii, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.