On 2025-03-13 1:36 p.m., Paul Koning via cctalk wrote:
Depends on which one. RTL was 3.6 volts positive, as far as I can remember. I actually
have a keyboard that has some of those devices in it. Yes, ECL is around 3 volts also
but negative supply. And of course some people designed systems with positive supplies
but "negative" logic, in the sense that ~0 volts is logic 1 while near-VCC is
logic 0; the CDC 6000 series machines are an example.
I was thinking of the PDP-8 there. 0 Volts logic 1 -3 volts logic 0.
FPGAs come in amazing sizes if you have sufficient money. I hope some day to
cram an entire CDC 6600 into an FPGA. The main problem with this isn't FPGA
sizes (by today's standards, an upper-midrange FPGA can do the job, memory
included) but rather the creation of an accurate model given the bizarre and
hairy timing of that machine. I have a gate level model, but it doesn't work
yet because of those issues.
What would the purpose of said computer be?
Might be better off with a clean 64 bit design and 16 bit bitslices.
paul
