not to in any way denigrate the design. its very cute an clever for simple controller applications. but it really kind of folds a few functions in the ur-instruction with reasonable interpretations that turn part of the machine into a nop.
the only part of the design that bothers me is the 2716. i think i've been spoiled by lots of years of having micro controllers one could program with a general purpose communications channel (hc11 shoutout)
i have to imagine this would be a great introduction to processors for non-specialists. a 20 chip ttl design with instruction decode and a register file and address multiplexing is beyond a lot of people's interest.
all those things are really here in concept though, just small enough that you can fit all of them in 8 bits.
>not to in any way denigrate the design. its very cute an clever for simple controller applications. but it really kind of folds a few functions in the ur-instruction with reasonable interpretations that turn part of the machine into a nop.
It's not like SUBLEQ is a very simple instruction either. It has to read two memory addresses, perform arithmetic, and write the result back, on top of possibly branching.
This machine writes a fixed bit to one address, and reads one bit from another address, branching on it. Even if you break it down into micro-ops, that's two instructions. Set-bit and branch. I'd call it simpler.
the only part of the design that bothers me is the 2716. i think i've been spoiled by lots of years of having micro controllers one could program with a general purpose communications channel (hc11 shoutout)
i have to imagine this would be a great introduction to processors for non-specialists. a 20 chip ttl design with instruction decode and a register file and address multiplexing is beyond a lot of people's interest.
all those things are really here in concept though, just small enough that you can fit all of them in 8 bits.
thanks for posting that