TOPS-20: Difference between revisions

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Change "is" to "was" since this operating system was discontinued decades ago.
 
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| family = [[TENEX (operating system)|TENEX]]
| family = [[TENEX (operating system)|TENEX]]
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The '''TOPS-20''' [[operating system]] by [[Digital Equipment Corporation]] (DEC) was a proprietary<ref>{{cite web|url=https://www.gnu.org/philosophy/stallman-kth.html|title=RMS lecture at KTH (Sweden)|date=30 October 1986|author=Richard Stallman}}</ref> OS used on some of DEC's 36-bit [[mainframe computer]]s. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC [[PDP-10]] and the [[DECSYSTEM-20]]).<ref name=CMDref>{{cite web
The '''TOPS-20''' [[operating system]] by [[Digital Equipment Corporation]] (DEC) is a proprietary<ref>{{cite web|url=https://www.gnu.org/philosophy/stallman-kth.html|title=RMS lecture at KTH (Sweden)|date=30 October 1986|author=Richard Stallman}}</ref> OS used on some of DEC's 36-bit [[mainframe computer]]s. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC [[PDP-10]] and the [[DECSYSTEM-20]]).<ref name=CMDref>{{cite web
|url=https://livingcomputers.org/UI/UserDocs/TOPS-20-v7-1/2_TOPS-20_Commands_Reference_Manual.pdf
|url=https://livingcomputers.org/UI/UserDocs/TOPS-20-v7-1/2_TOPS-20_Commands_Reference_Manual.pdf
|title=TOPS-20 Command manual
|title=TOPS-20 Command manual

Revision as of 15:34, 5 June 2025

Template:Short description Script error: No such module "Unsubst".Script error: No such module "Check for unknown parameters". The TOPS-20 operating system by Digital Equipment Corporation (DEC) is a proprietary[1] OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP-10 and the DECSYSTEM-20).[2]

TOPS-20 began in 1969 as the TENEX operating system of Bolt, Beranek and Newman (BBN) and shipped as a product by DEC starting in 1976.[3] TOPS-20 is almost entirely unrelated to the similarly named TOPS-10, but it was shipped with the PA1050 TOPS-10 Monitor Calls emulation facility which allowed most, but not all, TOPS-10 executables to run unchanged. As a matter of policy, DEC did not update PA1050 to support later TOPS-10 additions except where required by DEC software.

TOPS-20 competed with TOPS-10, ITS[4] and WAITS—all of which were notable time-sharing systems for the PDP-10 during this timeframe. TOPS-20 is informally known as TWENEX.[5]

TENEX

Script error: No such module "Labelled list hatnote". TOPS-20 was based upon the TENEX operating system, which had been created by Bolt Beranek and Newman for Digital's PDP-10 computer. After Digital started development of the KI-10 version of the PDP-10, an issue arose: by this point TENEX was the most popular customer-written PDP-10 operating systems, but it would not run on the new, faster KI-10s. To correct this problem, the DEC PDP-10 sales manager purchased the rights to TENEX from BBN and set up a project to port it to the new machine. In the end, very little of the original TENEX code remained, and Digital ultimately named the resulting operating system TOPS-20.

PA1050

Some of what came with TOPS-20 was merely an emulation of the TOPS-10 Operating System's calls. These were known as UUO's, standing for Unimplemented User Operation,[6] and were needed both for compilers, which were not 20-specific, to run, as well as user-programs written in these languages. The package that was mapped into a user's address space was named PA1050: PA as in PAT as in compatibility; 10 as in DEC or PDP 10; 50 as in a PDP 10 Model 50, 10/50, 1050.[7]

Sometimes PA1050 was referred to as PAT, a name that was a good fit to the fact that PA1050, "was simply unprivileged user-mode code" that "performed the requested action, using JSYS calls where necessary."[7]

TOPS-20 capabilities

The major ways to get at TOPS-20 capabilities, and what made TOPS-20 important, were

  • Commands entered via the command processor, EXEC.EXE[2]
  • JSYS (Jump to System) calls from MACro-language (.MAC) programs[8][9]

The "EXEC" accomplished its work primarily using

  • internal code, including calls via JSYS
  • requesting services from "GALAXY" components (e.g. spoolers)

Command processor

Rather advanced for its day were some TOPS-20-specific features:

  • noise-words - typing DIR and then pressing the ESCape key resulted in
DIRectory (of files)
typing Template:Keypress and pressing the Template:Keypress key resulted in
Information (about)

One could then type Template:Keypress to find out what operands were permitted/required. Pressing Template:Keypress displays status information.

Commands

The following list of commands are supported by the TOPS-20 Command Processor.[2]

Template:Div col

  • ACCESS
  • ADVISE
  • APPEND
  • ARCHIVE
  • ASSIGN
  • ATTACH
  • BACKSPACE
  • BLANK
  • BREAK
  • BUILD
  • CANCEL
  • CLOSE
  • COMPILE
  • CONNECT
  • CONTINUE
  • COPY
  • CREATE
  • CREF
  • CSAVE
  • DAYTIME
  • DDT
  • DEASSIGN
  • DEBUG
  • DEFINE
  • DELETE
  • DEPOSIT
  • DETACH
  • DIRECTORY
  • DISABLE
  • DISCARD
  • DISMOUNT
  • EDIT
  • ENABLE
  • END-ACCESS
  • EOF
  • ERUN
  • EXAMINE
  • EXECUTE
  • EXPUNGE
  • FDIRECTORY
  • FORK
  • FREEZE
  • GET
  • HELP
  • INFORMATION
  • KEEP
  • LOAD
  • LOGIN
  • LOGOUT
  • MERGE
  • MODIFY
  • MOUNT
  • PERUSE
  • PLOT
  • POP
  • PRINT
  • PUNCH
  • PUSH
  • RECEIVE
  • REENTER
  • REFUSE
  • REMARK
  • RENAME
  • RESET
  • RETRIEVE
  • REWIND
  • RUN
  • SAVE
  • SEND
  • SET
  • SET HOST
  • SKIP
  • START
  • SUBMIT
  • SYSTAT
  • TAKE
  • TALK
  • TDIRECTORY
  • TERMINAL
  • TRANSLATE
  • TYPE
  • UNATTACH
  • UNDELETE
  • UNKEEP
  • UNLOAD
  • VDIRECTORY

Template:Div col end

JSYS features

JSYS stands for Jump to SYStem.[10] Operands were at times memory addresses. "TOPS-20 allows you to use 18-bit or 30-bit addresses. Some monitor calls require one kind, some the other; some calls accept either kind. Some monitor calls use only 18 bits to hold an address. These calls interpret 18-bit addresses as locations in the current section."[2]

Internally, files were first identified, using a GTJFN (Get Job File Number) JSYS, and then that JFN number was used to open (OPENF) and manipulate the file's contents.

PCL (Programmable Command Language)

PCL (Programmable Command Language) is a programming language that runs under TOPS-20. PCL source programs are, by default, stored with Filetype .PCL, and enable extending the TOPS-20 EXEC via a verb named DECLARE. Newly compiled commands then become functionally part of the EXEC.[11][12][13][14]

PCL language features

PCL includes:[11]

  • flow control: DO While/Until, CASE/SELECT, IF-THEN-ELSE, GOTO
  • character string operations (length, substring, concatenation)
  • access to system information (date/time, file attributes, device characteristics)

TOPS-20 today

Paul Allen maintained several publicly accessible historic computer systems before his death, including an XKL TOAD-2 running TOPS-20.

See also SDF Public Access Unix System.

See also

References

Template:Reflist

Further reading

External links

Template:Digital Equipment Corporation Template:Time-sharing operating systems

  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ a b c d Script error: No such module "citation/CS1".
  3. ↑ a b Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b The 10/50 was the top-of-the-line KA machine at that time. Script error: No such module "citation/CS1". The family continued with another KA, the 10/55, and then came KI, KL & KS.
  8. ↑ The JSYS was the counterpart for the 20 of what was done by TOPS-10 on a "10" and thus the emulator for a DEC PDP-10 Model 50 was what PA1050 was emulating. The 10's system calls were known as UUO's
  9. ↑ Script error: No such module "citation/CS1".
  10. ↑ Script error: No such module "citation/CS1".
  11. ↑ a b Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
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