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Input/Output Control System

February 13, 2024

Input/Output Control System (IOCS) is any of several packages on early IBM entry-level and mainframe computers that provided low level access to records on peripheral equipment. IOCS provides functionality similar to 1960s packages from other vendors, e.g., File Control Processor (FCP)[1] in RCA 3301 Realcom Operating System, GEFRC[2] in GECOS, and to the later Record Management Services[3] (RMS) in DEC VAX/VMS (later OpenVMS.)

Computers in the 1950s and 1960s typically dealt with data that were organized into records either by the nature of the media, e.g., lines of print, or by application requirements. IOCS was intended to allow Assembler language programmers to read and write records without having to worry about the details of the various devices or the blocking of logical records into physical records. IOCS provided the run time I/O support for several compilers.

Computers of this era often did not have operating systems in the modern sense. Application programs called IOCS routines in a resident monitor, or included macro instructions that expanded to IOCS routines.

In some cases[4] IOCS was designed to coexist with Simultaneous Peripheral Operations On-line (SPOOL)[5] software.

The level of access is at a higher level than that provided by BIOS and BDOS in the PC world; in fact, IOCS has no support for character-oriented I/O, primarily because the systems for which it was designed didn't support it. Versions of IOCS existed for the IBM 705 III,[6] 1401/1440/1460, 1410/7010, 7070/7072/7074,[7][8][9] 7080[10] and 7040/7044/7090/7094.[11] These systems heavily influenced the data management components of the operating systems[12] for the System/360; the name IOCS was carried through in DOS/360 through z/VSE,[13] with a distinction between Logical IOCS (LIOCS)[14] and Physical IOCS (PIOCS).[14]

Although some technical details and nomenclature are different among the various IOCS packages, the fundamental concepts are the same. For concreteness, the discussion and examples in this article will mostly be in terms of 7070 IOCS.[7][8] Also, multiple continuation lines will be shown as ellipses (...) when they don't serve to illustrate the narrative.

Structure edit

An IOCS program must do three things, each discussed in a subsection below.

For the 7070 these are done using 7070 Autocoder[15][16] declarative statements and macro instructions.

Identify required IOCS services edit

IOCS supported several classes of I/O equipment

  • Disk drives
  • Tape drives
  • Unit record equipment. The record length was dictated by the physical media, which were
    • Lines of print on paper
    • Punched 80-column[a] cards

Some services offered by IOCS were not needed by all applications, e.g., checkpoints, label processing. An IOCS program must identify the particular devices types and services it uses. A 7070 IOCS program must specify one or more DIOCS[7]: 16–19 [15]: 22–25  statements:[b]

 11 22 6 56 01 GENERAL DIOCSgeneral parameters TAPE DIOCSD729,tape parameters DISK DIOCSD1301,disk parameters END DIOCS

These declarative statements identify index registers reserved for the use of IOCS, indicate channels used, indicate whether the program is to coexist with SPOOL and provide processing options. The END DIOCS statement causes the assembly of IOCS unless a preassembled version is requested. The first (general) form is omitted when the D729 form is used.

In some other IOCS packages similar functions are provided by control cards.

Create control blocks for individual files edit

An IOCS program must create a control block for each file, specifying information unique to the file. For 7070 IOCS these are entries in the File Specification Table for tape files, each of which is generated by a DTF[7]: 19–26 [15]: 26–28  statement, or separate control blocks generated by DDF[8]: 31–37 [15]: 29–30  or DUF[7]: 44–47 [15]: 31–33  statements. 

 11 22 6 56 01 DTF OUT FCHANNEL 2 ... ... DAFILE DDF IODEVICE 5 DREFMODE 4 ... ... DUF CONSFILE,1,4,CARDRDW,CARDIX,CONSEOF,CONSERR

In some other IOCS packages similar functions are provided by control cards.

Process files edit

The above code defines a tape file on channel 1 called OUT, a sequential 1301/1302 disk file called DAFILE and a card file called CONSFILE.

Any IOCS program must specify the actions that it wishes to perform. In 7070 IOCS this is done with processing macros.[b]

 11 22 6 56 01 OPEN CONSFILE,OUT LOOP GET CONSFILE PUT OUT B LOOP CONSEOF CLOSECONSFILE,OUT

In some other IOCS packages similar functions are provided by explicit subroutine calls.

See also edit

  • BIOS
  • Sharp IOCS, a similarly named system on 8-bit pocket computers by Sharp

Notes edit

  1. ^ IBM did not support the 90-column cards used by UNIVAC
  2. ^ a b Note that operands in 7070 Autocoder always start in column 21.

References edit

  1. ^ RCA 3301 Realcom Training Manual (PDF). RCA EDP Division. November 1964. 94-06-000.
  2. ^ GE-635 File and Record Control Reference Manual. GE. CPB-1003.
  3. ^ VAX-11 Record Management Services Reference Manual (PDF). DEC. February 1979. AA-D031B-TE.
  4. ^ IBM 7070 SPOOL System. IBM. J28-6047-1.
  5. ^ "SPOOL System", 7070-IO-076
  6. ^ Reference Manual Input/Output Control System for the IBM 705 III. IBM. C28-6109.
  7. ^ a b c d e IBM 7070/7074 Input/Output Control System for IBM 729 Magnetic Tape Units, Unit Record Equipment (7070-IO-904). IBM. C28-6175-3.
  8. ^ a b c IBM 7070/7074 Input/Output Control System for IBM 1301 and 1302 Disk Storage (7070-IO-940). IBM. C28-6272-1.
  9. ^ IBM Programming Systems Analysis Guide 7070 Input/Output Control System (PDF). IBM. 1961. C28-6119.
  10. ^ 7080 Input/Output Control System for use with 729 Magnetic Tape Units (PDF). IBM. C28-6237.
  11. ^ Reference Manual, IBM 709/7090 Input/output Control System (PDF). IBM. C28-6100-2.
  12. ^ IBM Operating System/360 Concepts and Facilities (PDF). IBM. C28-6535-0.
  13. ^ IBM z/VSE Version 6 Release 1 System Macros User's Guide (PDF). IBM. 2015. SC34-2709-00.
  14. ^ a b DOS Supervisor and I/O Macros (PDF). IBM. GC24-S037-12.
  15. ^ a b c d e IBM 7070 Programming Series Autocoder. IBM. C28-6121-3.
  16. ^ IBM 7070 Four Tape Autocoder. IBM. J28-6055.
  • Bashe, Charles J.; Johnson, Lyle R.; Palmer, John H.; Pugh, Emerson W. (1986). IBM's Early Computers. History of Computing. MIT Press. pp. 362–363. ISBN 0-262-02225-7.
  • Bohl, M. (1971). Information Processing. Science Research Associates.
  • Cenfetelli, A. R. (1967). "Data Management Concepts for DOS/360 and TOS/360". IBM Systems Journal. IBM. 6 (1): 22–37. doi:10.1147/sj.61.0022.
  • Deitel, Harvey M. (1983). An Introduction to Operating Systems. Addison Wesley Systems Programming Series. Addison Wesley. pp. 10–11, 35, 158. ISBN 0-201-14473-5.
  • Freeman, Donald E.; Perry, Olney R. (1977). I/O Design: Data Management in Operating Systems. History of Computing. HAYDEN. p. 3. ISBN 0-8104-5789-X.
  • Katzan, Jr., Harry (1973). Operating Systems: A Pragmatic Approach. VNR. pp. 98, 101–102. ISBN 0-442-24253-0.
  • Lorin, Harold; Deitel, Harvey M. (1981). Operating Systems. Addison Wesley. p. 74. ISBN 0-201-14464-6.
  • Milenkovic, Milan (1987). Operating Systems: Concepts and Design. McGraw-Hill. ISBN 0-07-100583-8.
  • Pugh, Emerson W.; Johnson, Lyle R.; Palmer, John H. (1991). IBM's 360 and Early 370 Systems. History of Computing. MIT Press. pp. 295, 324, 326, 561–562, 590. ISBN 0-262-16123-0.
  • Shaw, Alan C. (1974). The Logical Design of Operating Systems. Prentice-Hall Series In Automatic Computation. Prentice-Hall. ISBN 0-13-540112-7.

External links edit

  • "RCA 3301 Realcom Training Manual", 94-06-000, November 1964
  • history of operating systems
  • Operating Systems - History of Operating System
  • Pease, David. . University of California Santa Cruz. Archived from the original on 2010-06-12. Retrieved 2020-08-27.
  • Computer Hardware and System Software Concepts

February 13, 2024
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Input Output Control System IOCS is any of several packages on early IBM entry level and mainframe computers that provided low level access to records on peripheral equipment IOCS provides functionality similar to 1960s packages from other vendors e g File Control Processor FCP 1 in RCA 3301 Realcom Operating System GEFRC 2 in GECOS and to the later Record Management Services 3 RMS in DEC VAX VMS later OpenVMS Computers in the 1950s and 1960s typically dealt with data that were organized into records either by the nature of the media e g lines of print or by application requirements IOCS was intended to allow Assembler language programmers to read and write records without having to worry about the details of the various devices or the blocking of logical records into physical records IOCS provided the run time I O support for several compilers Computers of this era often did not have operating systems in the modern sense Application programs called IOCS routines in a resident monitor or included macro instructions that expanded to IOCS routines In some cases 4 IOCS was designed to coexist with Simultaneous Peripheral Operations On line SPOOL 5 software The level of access is at a higher level than that provided by BIOS and BDOS in the PC world in fact IOCS has no support for character oriented I O primarily because the systems for which it was designed didn t support it Versions of IOCS existed for the IBM 705 III 6 1401 1440 1460 1410 7010 7070 7072 7074 7 8 9 7080 10 and 7040 7044 7090 7094 11 These systems heavily influenced the data management components of the operating systems 12 for the System 360 the name IOCS was carried through in DOS 360 through z VSE 13 with a distinction between Logical IOCS LIOCS 14 and Physical IOCS PIOCS 14 Although some technical details and nomenclature are different among the various IOCS packages the fundamental concepts are the same For concreteness the discussion and examples in this article will mostly be in terms of 7070 IOCS 7 8 Also multiple continuation lines will be shown as ellipses when they don t serve to illustrate the narrative Contents 1 Structure 1 1 Identify required IOCS services 1 2 Create control blocks for individual files 1 3 Process files 2 See also 3 Notes 4 References 5 External linksStructure editAn IOCS program must do three things each discussed in a subsection below Identify required IOCS services Create control blocks for individual files Process filesFor the 7070 these are done using 7070 Autocoder 15 16 declarative statements and macro instructions Identify required IOCS services edit IOCS supported several classes of I O equipment Disk drives Tape drives Unit record equipment The record length was dictated by the physical media which were Lines of print on paper Punched 80 column a cardsSome services offered by IOCS were not needed by all applications e g checkpoints label processing An IOCS program must identify the particular devices types and services it uses A 7070 IOCS program must specify one or more DIOCS 7 16 19 15 22 25 statements b 11 22 6 56 01 GENERAL DIOCSgeneral parameters TAPE DIOCSD729 tape parameters DISK DIOCSD1301 disk parameters END DIOCS These declarative statements identify index registers reserved for the use of IOCS indicate channels used indicate whether the program is to coexist with SPOOL and provide processing options The END DIOCS statement causes the assembly of IOCS unless a preassembled version is requested The first general form is omitted when the D729 form is used In some other IOCS packages similar functions are provided by control cards Create control blocks for individual files edit An IOCS program must create a control block for each file specifying information unique to the file For 7070 IOCS these are entries in the File Specification Table for tape files each of which is generated by a DTF 7 19 26 15 26 28 statement or separate control blocks generated by DDF 8 31 37 15 29 30 or DUF 7 44 47 15 31 33 statements 11 22 6 56 01 DTF OUT FCHANNEL 2 DAFILE DDF IODEVICE 5 DREFMODE 4 DUF CONSFILE 1 4 CARDRDW CARDIX CONSEOF CONSERR In some other IOCS packages similar functions are provided by control cards Process files edit The above code defines a tape file on channel 1 called OUT a sequential 1301 1302 disk file called DAFILE and a card file called CONSFILE Any IOCS program must specify the actions that it wishes to perform In 7070 IOCS this is done with processing macros b 11 22 6 56 01 OPEN CONSFILE OUT LOOP GET CONSFILE PUT OUT B LOOP CONSEOF CLOSECONSFILE OUT In some other IOCS packages similar functions are provided by explicit subroutine calls See also editBIOS Sharp IOCS a similarly named system on 8 bit pocket computers by SharpNotes edit IBM did not support the 90 column cards used by UNIVAC a b Note that operands in 7070 Autocoder always start in column 21 References edit RCA 3301 Realcom Training Manual PDF RCA EDP Division November 1964 94 06 000 GE 635 File and Record Control Reference Manual GE CPB 1003 VAX 11 Record Management Services Reference Manual PDF DEC February 1979 AA D031B TE IBM 7070 SPOOL System IBM J28 6047 1 SPOOL System 7070 IO 076 Reference Manual Input Output Control System for the IBM 705 III IBM C28 6109 a b c d e IBM 7070 7074 Input Output Control System for IBM 729 Magnetic Tape Units Unit Record Equipment 7070 IO 904 IBM C28 6175 3 a b c IBM 7070 7074 Input Output Control System for IBM 1301 and 1302 Disk Storage 7070 IO 940 IBM C28 6272 1 IBM Programming Systems Analysis Guide 7070 Input Output Control System PDF IBM 1961 C28 6119 7080 Input Output Control System for use with 729 Magnetic Tape Units PDF IBM C28 6237 Reference Manual IBM 709 7090 Input output Control System PDF IBM C28 6100 2 IBM Operating System 360 Concepts and Facilities PDF IBM C28 6535 0 IBM z VSE Version 6 Release 1 System Macros User s Guide PDF IBM 2015 SC34 2709 00 a b DOS Supervisor and I O Macros PDF IBM GC24 S037 12 a b c d e IBM 7070 Programming Series Autocoder IBM C28 6121 3 IBM 7070 Four Tape Autocoder IBM J28 6055 Bashe Charles J Johnson Lyle R Palmer John H Pugh Emerson W 1986 IBM s Early Computers History of Computing MIT Press pp 362 363 ISBN 0 262 02225 7 Bohl M 1971 Information Processing Science Research Associates Cenfetelli A R 1967 Data Management Concepts for DOS 360 and TOS 360 IBM Systems Journal IBM 6 1 22 37 doi 10 1147 sj 61 0022 Deitel Harvey M 1983 An Introduction to Operating Systems Addison Wesley Systems Programming Series Addison Wesley pp 10 11 35 158 ISBN 0 201 14473 5 Freeman Donald E Perry Olney R 1977 I O Design Data Management in Operating Systems History of Computing HAYDEN p 3 ISBN 0 8104 5789 X Katzan Jr Harry 1973 Operating Systems A Pragmatic Approach VNR pp 98 101 102 ISBN 0 442 24253 0 Lorin Harold Deitel Harvey M 1981 Operating Systems Addison Wesley p 74 ISBN 0 201 14464 6 Milenkovic Milan 1987 Operating Systems Concepts and Design McGraw Hill ISBN 0 07 100583 8 Pugh Emerson W Johnson Lyle R Palmer John H 1991 IBM s 360 and Early 370 Systems History of Computing MIT Press pp 295 324 326 561 562 590 ISBN 0 262 16123 0 Shaw Alan C 1974 The Logical Design of Operating Systems Prentice Hall Series In Automatic Computation Prentice Hall ISBN 0 13 540112 7 External links edit RCA 3301 Realcom Training Manual 94 06 000 November 1964 history of operating systems Operating Systems History of Operating System Pease David History of Modern Computing Section 3 University of California Santa Cruz Archived from the original on 2010 06 12 Retrieved 2020 08 27 Computer Hardware and System Software Concepts Retrieved from https en wikipedia org w index php title Input Output Control System amp oldid 1070317461, wikipedia, wiki, book, books, library,

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