The PDP-6 is a 36 bit computer architecture developed by Digital Equipment Corporation in about 1963. It was constructed from system modules, an early form of digital logic based on germanium transistors. The logic was powered by -15 volt supplies, with a +10 volt bias. Logic levels were 0 and -3 volts.
Logic pulses, delay lines, and pulse transformers were widely used to construct asynchronous logic networks.
Here is the postscript scan of hardware maintenance manual for the type 166 processor and peripherals which formed the basis of the PDP-6 processor family. Warning -- this is BIG -- 20 megabytes.
Here is the postscript scan of the schematic print set for the 166 processor. Warning -- this is BIG -- 8 megabytes.
More to come.