On: PDP-11 Booting

[ghostly_s]

well this is disappointing..."binary toggles" had me picturing a single 3-way toggle switch where you manually entered ones and zeroes.

[breput → ghostly_s]

That is exactly what is going on but you don't need 3 way toggle.

Down is 0 and up is 1, you load all of the values in like a shift register but in parallel, then write/act upon them.

[DrTung → breput]

Yes the data bits were 2-way toggles, but one important switch was a 3-way toggle: the Examine (press down) and Deposit (press up) switch.

[breput → DrTung]

On the 11/70, Deposit was the only switch that toggled up (other than the light test switch). That is a nice safety feature so you don't accidentally toggle Continue or other action switches.

[ghostly_s → breput]

Right...but surely you see how that's different from what I described.