TOPS-20 Commands Reference Manual


Moves a magnetic tape set backward over a specified number of files or records.


@BACKSPACE (DEVICE) dev:  n units


dev: is the name of the tape set or magnetic tape drive that you want to move backward. The colon after the device name is optional.
n is the number of files or records over which you want to backspace.

Default n - 1

units is either FILES or RECORDS.

Default units - FILES


BACKSPACE with Open Files

If you have given a CTRL/C to exit from a program that has opened a magnetic tape drive and you then give the BACKSPACE command for that tape drive, the system will first ask if you want to close the associated file. You must do so for BACKSPACE to succeed, but you will probably be unable to continue the program from that point because the file will now be closed.

RECORDS Argument Used for Unlabeled Tapes Only

You cannot give the RECORDS argument to the BACKSPACE command when using a labeled tape, because read and write operations for labeled tapes always move the tape to the beginning of a file first.

Related Commands

SKIP for moving a magnetic tape set forward
REWIND for backspacing a tape volume or tape set to its logical beginning (the beginning of the first file)
UNLOAD for completely rewinding a magnetic tape onto the source reel


  1. Backspace your magnetic tape one file.