===== TOPS-20 Operating System =====

TOPS-20 command parser is called EXEC. EXEC features built in help, command recognition and completion.  If you are [[:twenex.org_-_sdf_public_access_twenex |new]] to TOPS-20, try the //tops20// command when you LOGIN for an interactive tutorial.

^ **Command** ^ **Description** ^
| CTRL-C     | Interrupts or quits a job (see reenter) |
| CTRL-F     | Try this to show command completion |
| CTRL-T     | Prints job status                       |
| <ESCAPE>   | Try this to show completion and //guide words// |
| CONTINUE   | Continues a suspended or quit job       |
| DIR        | DIRECTORY listing (see vdir)            |
| EMACS      | The EMACS editor - Try '//TEACH-EMACS//' |
| FINGER     | Display who is logged in or details on a specific user |
| HELP       | The HELP system - Try '//HELP GAMES//'  |
| INFO       | INFORMATION about various subsystems    |
| KJOB       | KILL JOB - With out args will log you out |
| LOGIN      | Login to a user account                 | 
| LOGOUT     | Logout from the system, see KJOB        |
| REENTER    | re-enters a suspended or quit job       |
| SYSTAT     | System Status - Shows running jobs      |
| VDIR       | Verbose Directory listing               |

The directory structure is hierarchical and some notable directories also include logical names.  To see a complete list of defined LOGICAL-NAMES type //INFORMATION LOGICAL-NAMES ALL// or //inf log a// 

^ **Directory Name** ^ **Logical Name** ^ **Description** ^
| <DOCUMENTATION> | DOC: | Various Documentation |
| <HELP> | HLP: | The HELP system |
| <SUBSYS> | SYS: | Subsystem utilities and user programs |
| <SYSTEM> | SYSTEM: | The SYSTEM directory - The Monitor and system configuration live here |
| <UNSUPPORTED> | UNS: | 3rd party programs such as games |

**PROGRAMMING EXAMPLES USING "COMPILE", "LOAD" and "SAVE" COMMANDS**

TOPS-20 supports many programming languages using a standard COMPILE/LOAD/SAVE model.  TOPS-20 is very helpful using command recognition and DWIM (Do What I Mean) without having to completely type out everything.  Here are few simple examples to get started:

**FORTRAN-77**

//NOTE: This formatting is punched card style - The first 5 and 6th columns are special//

      @copy TTY: test.for                             ;A simple way to enter in TEXT from the terminal
       TTY: => TEST.FOR.1
      
               PROGRAM TEST                           ;Declare the name of the program
      
               WRITE (5, 10)                          ;OUTPUT to the terminal (UNIT 5) at line 10
      10       FORMAT(' TESTING 1 2 3!')              ;FORMAT the text for OUTPUT
      
               END                                    ;END the program
      ^Z                                              ;CTRL-Z closes the file
      @type test.for                                  ;TYPE the test.for file and verify
               PROGRAM TEST
      
               WRITE (5, 10)
      10       FORMAT(' TESTING 1 2 3!')
            
               END
      @compile test                                   ;COMPILE the file TEST
      FORTRAN: TEST                                   ;COMPILE determined TEST is a FORTRAN program
      TEST  	                                      ;TEST is now written out as a .REL file
      @load test                                      ;LOAD the file (or EXECUTE TEST to LOAD and RUN)
      LINK:	Loading
      @save test                                      ;SAVE the loaded program to a .EXE file
       TEST.EXE.1 Saved
      @v test.*
            
         LS:<SMJ.FORTRAN>
       TEST.EXE.1;P775200         6 3072(36)    6-May-2020 15:42:13 SMJ       
         .FOR.1;P775200           1 71(7)       6-May-2020 15:41:09 SMJ       
         .REL.1;P775200           1 93(36)      6-May-2020 15:41:46 SMJ       
            
       Total of 8 pages in 3 files
       
       @<smj.fortran>test                             ;Run the .EXE file
       TESTING 1 2 3!
       CPU time 0.09   Elapsed time 0.19

For an excellent summary to get started with FORTRAN on TOPS-20, check out
[[http://wiki.twenex.org/doku.php?id=tutorials:fortran]]

**MACRO-20**

MACRO is the assembler on TOPS-20.  Here is a simple example of a Hello World in MACRO

       @COPY TTY:hello.mac                             ;A simple way to enter text into a file
       title hello                                      
       
       entry output
       search uuosym
       
       hello:	asciz /Hello there.
       
       /
       output:	outstr hello
       	monrt.
       	end output
       ^Z
       
       @type hello.mac
       title hello
       
       entry output
       search uuosym
       
       hello:	asciz /Hello there.
       
       /
       output:	outstr hello
       	monrt.
       	end output
       @compile hello
       MACRO:	hello
       
       EXIT
       @load hello
       LINK:	Loading
       @save hello
        HELLO.EXE.1 Saved
       @<smj>hello
       Hello there.


Visit our repository for //[[https://web.archive.org/web/20240426225029/https://www.livingcomputers.org/Computer-Collection/Online-Systems/User-Documentation.aspx |User Documentation]] (archived)//‚ for //Online Systems//‚ for formal user and reference manual.