TOPS-20 Commands Reference Manual

Appendix D Control characters

This appendix lists the TOPS-20 control characters. To type a control character, use the CTRL key like the SHIFT key. Hold down the CTRL key and at the same time type the character key.

CTRL/C Cancels a command when typed during command entry.

Cancels command execution when typed twice during command execution. (The first ^C does not echo.)

Halts a program and returns to TOPS-20 command level. Generally, type two CTRL/Cs to halt a program that is executing; type one CTRL/C to stop a program that is waiting for input.

CTRL/E Ends an ADVISE command link between two terminals.
CTRL/F Provides recognition input for file specifications and command names and arguments. Similar to the ESCAPE key, except that it completes only one field at a time with file specifications and it does not supply guidewords with commands.
CTRL/G Rings the terminal bell. Use with SEND and TALK commands to signal another user.
CTRL/H Reprints a command line up to the field that is in error. Type immediately after the input error message. Duplicates the function of the BACKSPACE key.
CTRL/I Duplicates the function of the TAB key.
CTRL/L Advances the paper on a hard-copy terminal to the top of the next page. To stop the ^L from printing, give the TERMINAL NO INDICATE command.
CTRL/O Stops output to the terminal while the program or command continues to execute.

Output resumes when:

  • another CTRL/O is typed
  • the program or command finishes
  • the program prompts for input
CTRL/Q Continues scrolling terminal output that was paused by CTRL/S or a pause on an end of page. Use the TERMINAL PAUSE (ON) CHARACTER command to define alternate pause and continue characters. Use the TERMINAL NO PAUSE (ON) END-OF-PAGE command to stop pause on an end of page. Use the TERMINAL LENGTH command to set the page length.
CTRL/R Reprints the current command line, incorporating the corrections made with the DELETE key or CTRL/W. Use on hard-copy terminals when backslashes and underscores caused by editing with DELETE and CTRL/W make the command line difficult to read. Use on video terminals when a system message covers the command line.
CTRL/S Pauses scrolling of terminal output until CTRL/Q is typed. Input, though not displayed, is accepted into the input buffer and processed after a CTRL/Q. Use the TERMINAL PAUSE (ON) CHARACTER command to define alternate pause and continue characters.
CTRL/T Displays a line of information that includes:
  • the time
  • the name and status of the current fork
  • the amount of CPU time used
  • the time elapsed since login
  • the system's load average
CTRL/U Erases the current command line. On hard-copy terminals, cancels the command and prints three Xs at the end of the command line.
CTRL/V Allows special characters (any character other than an alphanumeric, or the special characters - _ . or $) in file specifications and directory names. Type CTRL/V before typing the special character any time you type the file specification.

Special characters are not accepted by the following system programs:

CTRL/W Erases the previous word. On hard-copy terminals, cancels the previous word and types an underscore.
CTRL/Z Signals an end-of-file for data entered from the terminal. Use when: COPYing from your terminal (device TTY:) to a file. Sending a message with one of the mail programs.