fbpx
Wikipedia

Texas Instruments SN76489

March 10, 2023

The SN76489[1] Digital Complex Sound Generator (DCSG) is a TTL-compatible programmable sound generator chip from Texas Instruments.[2] Its main application was the generation of music and sound effects in game consoles, arcade games and home computers (such as the TI-99/4A, BBC Micro, ColecoVision, IBM PCjr, Tomy Tutor, and Tandy 1000), competing with the similar General Instrument AY-3-8910.

Pinout of the standard Texas Instruments SN76489 chip. The packaging is a standard 16-pin DIP.

It contains:[1]

  • 3 square wave tone generators.
    • A wide range of frequencies.
    • 16 different volume levels.
  • 1 noise generator.
    • 2 types (white noise and periodic).
    • 3 different frequencies.
    • 16 different volume levels.

Overview

The SN76489 was originally designed to be used in the TI-99/4 computer, where it was first called the TMS9919 and later SN94624, and had a 500 kHz max clock input rate. Later, when it was sold outside of TI, it was renamed the SN76489, and a divide-by-8 was added to its clock input, increasing the max clock input rate to 4 MHz, to facilitate sharing a crystal for both NTSC colorburst and clocking the sound chip. A version of the chip without the divide-by-8 input was also sold outside of TI as the SN76494, which has a 500 kHz max clock input rate.[1]

Tone Generators

The frequency of the square waves produced by the tone generators on each channel is derived from two factors:

  1. The speed of the external clock
  2. A 10-bit value provided in a control register for that channel (called N)

Each channel's frequency is arrived at by dividing the external clock by 4 (or 32 depending on the chip variant), and then dividing the result by N.[1] Thus the overall divider range is from 4 to 4096 (or 32 to 32768). At maximum clock input rate, this gives a frequency range of 122 Hz to 125 kHz. Or typically 108 Hz to 111.6 kHz, with an NTSC colorburst (~3.58 MHz) clock input – a range from roughly A2 (two octaves below middle A) to 5–6 times the generally accepted limits of human audio perception.

Noise Generator

The pseudorandom noise feedback is generated from an XNOR of bits 12 and 13 for feedback, with bit 13 being the noise output. The pseudorandom generator is cleared to 0s (with the feedback bit set to 1) on writes to chip register 6, the noise mode register.[1]

Product Family

There are two versions of the SN76489: the SN76489 (Narrow DIP version labeled SN76489N) and the SN76489A (Narrow DIP version labeled SN76489AN). The former was made around 1980–1982 and the latter from 1983 onward. They differ in that the output of the SN76489 is the inverse of the expected waveform (the waveform "grows" towards 0 V from 2.5 V), while the SN76489A the waveform is not inverted.

The SN76496 seems to be totally identical to the SN76489A in terms of the outputs produced, but features an "AUDIO IN" pin (on pin 9) for integrated audio mixing.[3]

SN76489 Product Family
Chip Variant Freq (max) Audio In
TMS9919 / SN94624 500 kHz No
SN76489 / SN76489A 4 MHz No
SN76494 / SN76494A 500 kHz Yes
SN76496 / SN76496A 4 MHz Yes

Clones and successors

Sega used real SN76489AN chips in their SG-1000 game console and SC-3000 computer, but used SN76489A clones in their Master System, Game Gear, and Sega Genesis game consoles. These modified sound chips were incorporated into the systems' video display processor (VDP). Although basic functionality is almost identical to that of the original SN76489A, a few small differences exist:

  • The randomness for the noise channel is generated differently.
  • The Game Gear's version includes an additional flag register that designates which speaker(s) each audio channel are output (left, right, or both).
  • The periodic noise is 16 stages long rather than 15; this makes a significant difference for music/programs which use periodic noise, as sounds will play at 6.25% lower pitch than on the TI-made chips.[4]

Another clone is the NCR 8496, used in some models of the Tandy 1000 computer. Later Tandy 1000 machines (notably the SL, TL and RL series) integrated the SN76496's functionality into the PSSJ ASIC.

Usage

Arcade video games

Home hardware

References

  1. ^ a b c d e Engineering staff of Texas Instruments Semiconductor Group. "SN 76489 AN" (PDF).
  2. ^ SN76489AN - Manual (PDF). Texas Instruments.
  3. ^ "SN76494, SN76494A, SN76496, SN76496A programmable tone/noise generator" (PDF). Texas Instruments. 1989 [1984].
  4. ^ Maxim (April 27, 2005). . SMS Power!. Archived from the original on May 17, 2006.

External links

 
Wikimedia Commons has media related to SN76489.
  • SN76489 Sound Chip Details
  • SN76489 on the Video Game Music Preservation Foundation wiki
  • SN76489 on SMSPower.org

March 10, 2023
texas, instruments, sn76489, sn76489, digital, complex, sound, generator, dcsg, compatible, programmable, sound, generator, chip, from, texas, instruments, main, application, generation, music, sound, effects, game, consoles, arcade, games, home, computers, su. The SN76489 1 Digital Complex Sound Generator DCSG is a TTL compatible programmable sound generator chip from Texas Instruments 2 Its main application was the generation of music and sound effects in game consoles arcade games and home computers such as the TI 99 4A BBC Micro ColecoVision IBM PCjr Tomy Tutor and Tandy 1000 competing with the similar General Instrument AY 3 8910 Pinout of the standard Texas Instruments SN76489 chip The packaging is a standard 16 pin DIP It contains 1 3 square wave tone generators A wide range of frequencies 16 different volume levels 1 noise generator 2 types white noise and periodic 3 different frequencies 16 different volume levels Contents 1 Overview 1 1 Tone Generators 1 2 Noise Generator 2 Product Family 3 Clones and successors 4 Usage 4 1 Arcade video games 4 2 Home hardware 5 References 6 External linksOverview EditThe SN76489 was originally designed to be used in the TI 99 4 computer where it was first called the TMS9919 and later SN94624 and had a 500 kHz max clock input rate Later when it was sold outside of TI it was renamed the SN76489 and a divide by 8 was added to its clock input increasing the max clock input rate to 4 MHz to facilitate sharing a crystal for both NTSC colorburst and clocking the sound chip A version of the chip without the divide by 8 input was also sold outside of TI as the SN76494 which has a 500 kHz max clock input rate 1 Tone Generators Edit The frequency of the square waves produced by the tone generators on each channel is derived from two factors The speed of the external clock A 10 bit value provided in a control register for that channel called N Each channel s frequency is arrived at by dividing the external clock by 4 or 32 depending on the chip variant and then dividing the result by N 1 Thus the overall divider range is from 4 to 4096 or 32 to 32768 At maximum clock input rate this gives a frequency range of 122 Hz to 125 kHz Or typically 108 Hz to 111 6 kHz with an NTSC colorburst 3 58 MHz clock input a range from roughly A2 two octaves below middle A to 5 6 times the generally accepted limits of human audio perception Noise Generator Edit The pseudorandom noise feedback is generated from an XNOR of bits 12 and 13 for feedback with bit 13 being the noise output The pseudorandom generator is cleared to 0s with the feedback bit set to 1 on writes to chip register 6 the noise mode register 1 Product Family EditThere are two versions of the SN76489 the SN76489 Narrow DIP version labeled SN76489N and the SN76489A Narrow DIP version labeled SN76489AN The former was made around 1980 1982 and the latter from 1983 onward They differ in that the output of the SN76489 is the inverse of the expected waveform the waveform grows towards 0 V from 2 5 V while the SN76489A the waveform is not inverted The SN76496 seems to be totally identical to the SN76489A in terms of the outputs produced but features an AUDIO IN pin on pin 9 for integrated audio mixing 3 SN76489 Product Family Chip Variant Freq max Audio InTMS9919 SN94624 500 kHz NoSN76489 SN76489A 4 MHz NoSN76494 SN76494A 500 kHz YesSN76496 SN76496A 4 MHz YesClones and successors EditSega used real SN76489AN chips in their SG 1000 game console and SC 3000 computer but used SN76489A clones in their Master System Game Gear and Sega Genesis game consoles These modified sound chips were incorporated into the systems video display processor VDP Although basic functionality is almost identical to that of the original SN76489A a few small differences exist The randomness for the noise channel is generated differently The Game Gear s version includes an additional flag register that designates which speaker s each audio channel are output left right or both The periodic noise is 16 stages long rather than 15 this makes a significant difference for music programs which use periodic noise as sounds will play at 6 25 lower pitch than on the TI made chips 4 Another clone is the NCR 8496 used in some models of the Tandy 1000 computer Later Tandy 1000 machines notably the SL TL and RL series integrated the SN76496 s functionality into the PSSJ ASIC Usage EditArcade video games Edit These games shared a common board design by Tehkan that used three of the functionally identical SN76496 Baluba Louk No Densetsu Senjyo Star Force These games shared a common board design by Universal Entertainment Corporation Lady Bug used 2 Mr Do used 2 of a functionally identical part labeled U8106 Mr Do s Castle used 4 Mr Do s Wild Ride used 4 Do Run Run used 4 From Konami Mikie Road Fighter Rush n Attack Time Pilot 84 used a functionally identical part labeled Y2404 From Sega Bank Panic Super Locomotive Sega Mega Tech Sega System 1 Sega System 2 Sega System E based on the Master System and used the clone chip in its VDP Sega ZaxxonHome hardware Edit ALF s Music Card MC1 Apple II add on card used three chips for a total of nine voices plus noise Bandai RX 78 BBC Master BBC Micro Coleco Adam ColecoVision used the SN76489AN Geneve 9640 IBM PCjr used the SN76489AN Memotech MTX Neo Geo Pocket Neo Geo Pocket Color used a T6W28 SN76489 like clone Sega Game Gear used a clone integrated into its VDP that has an additional speaker output register for simple stereo support Sega Genesis used a clone SEGA PSG integrated into its VDP as a secondary sound chip Sega Master System used a clone SEGA PSG integrated into its VDP Sega Pico Sega SG 1000 used the SN76489AN Sharp MZ 800 used the SN76489AN Sord M5 Tandy 1000 early systems used SN76496 or NCR 8496 later systems integrated into PSSJ ASIC SN76489 ISA Soundboard Hobbyist Soundcard for IBM XT PC Lo Tech Tandy Soundboard Prototype Soundcard for IBM XT PC TI 99 4A used the original TMS9919 Tomy Tutor Toshiba Pasopia 7 VTech CreatiVisionReferences Edit a b c d e Engineering staff of Texas Instruments Semiconductor Group SN 76489 AN PDF SN76489AN Manual PDF Texas Instruments SN76494 SN76494A SN76496 SN76496A programmable tone noise generator PDF Texas Instruments 1989 1984 Maxim April 27 2005 SN76489 notes SMS Power Archived from the original on May 17 2006 External links Edit Wikimedia Commons has media related to SN76489 SN76489 Sound Chip Details SN76489 on the Video Game Music Preservation Foundation wiki SN76489 on SMSPower org Portals Electronics Video games 1980s 1990s Retrieved from https en wikipedia org w index php title Texas Instruments SN76489 amp oldid 1126434285, 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.