As a high school student, I stopped our PDP-8 while it was running BASIC, then toggled in a little machine loop that changed all the occurrences of the 12-bit value that represented "Clear the Accumulator" with the 12-bit value that represented "Load the Switch Register into the Accumulator". I then loaded the soft-restart address into the program counter, set the switch register to 0, then used the continue switch to soft restart BASIC.

Surprisingly, everything appeared to work fine, until the following day, when someone soft restarted BASIC, but left one of the toggles up (because the soft restart address was octal 0200).

I wrote this up in more detail at https://ctm.github.io/docs/yld/programming/pdp8/first-hack.h...