> On Mar 13, 2025, at 3:28 PM, ben via cctalk <[email protected]> wrote:
>
> On 2025-03-13 12:24 p.m., Martin Bishop via cctalk wrote:
>> One FPGA will easily do a VLIW sequencer + scalar mills (one or more, memory
>> / MAC assemblies) or a simple processor
>
> When it works.
> I see lots low cost Chinese FPGA cards, so that is valid option.
>
>> Something like https://www.aliexpress.com/item/1005005779045608.html
>> provides a wholly adequate platform for a microcoded processor, with lots of
>> 3v3 IO for external logic analysis inputs
>
> They goofed on that, 3 volt transistor logic is negative. :)
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.
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.
paul
