3 ms·

21 bits ... allows front panel access to more than the 16 bits of the machine registers. smokin'!

• ch_123 8y ago
  The /70 had a 22-bit address bus, so I assume that switches 16-21 didn't have any effect unless you were entering a memory address.
  • jtlienwis 8y ago
    I read something that said Ken Olsen found these switches on an old model washing machine and thought they would be great on the PDP machines.
    • jtlienwis 8y ago
      I think it might have been the 1957 Philco-Bendix Duomatic washer/dryer front switches that inspired the PDP-11 panel.