Re: Whether something is RISC or not (Re: PDP-8 theology, not Concertina II Progress)

EricP wrote:

 Yes, I was referring to its 16-bit internal bus structure.
This M68000 patent from 1978 shows it in Fig 2:

Patent US4296469 Execution unit for data processor using
segmented bus structure, 1978
https://patents.google.com/patent/US4296469A/en

There are a number of interesting things about those segmented busses::
a) the busses were true-complement
b) the busses were precharged
c) the busses were coupled with 2 pass gates on either side of a
   3 transistor sense amplifier
d) to copy data from one bus to the next buss one
   1) opened up the pass gates on the active bus
   2) fired the sense amplifier
   3) opened up the pass gate to the next bus
So, in 7 transistors, one got::
a) bus to bus isolation
b) bus to bus data copy in either direction
c) and a bus flip-flop (fired sense amplifier)
This would take at least 30 transistors with todays technology
to do what they did in 7.