# 2023-09-27 — Dev notes

- Add `REW` rewind instruction for tape control?
- (and `BSP` 'backspace'?)

IBM 701 halts the machine and lights a 'checko

IBM 701 (24-6042-1_701_PrincOps.pdf):

If a copy instruction is given when there is no read-write component connected to the computing unit (e.g., fi nO READ Or WRITE instruction has been given, or fi a coPY has been given too late), the cal-
culator stops and a copy-check light turns on, indi- cating an error in the program.