[Coco] Multipak redesign/replacement / New CoCo...

[RETRO Innovations]

On 2/23/2015 10:18 PM, Gene Heskett wrote:
> Oh look, all those flashing leds must mean its working right? ;-)
> Actually, that is one feature creep I'd pay for happily Jim.  Their value as a
> troubleshooting tool outweighs the cost IMO.
:-)
>
>> As for the other designs, the 8 slot unit was gargantuan, and I wanted
>> something I thought would be of interest, challenging enough to allow me
>> to learn this platform, but not so large as to be a debug nightmare.
>> The MPI design looked fine, but I felt I could minimize TTL count by
>> using a CPLD, and still provide the same functionality.
> I am sure it could, so all I'll mention is the additive delays can be a
> nuisance.  Check those carefully.
I'll post the schematic as soon as I finish, but I think all signal 
paths are ~9ns (2ns for the HCT buffers, + 7ns worst case in the 
CPLD).   CART, SCS, and CTS are handled directly in the CPLD, so no need 
for muxes or decoders like the 139s and the 157s in the MPI. So, 10nS 
should be worst case at 25C.

The cable is a concern.  My google fu isn;t finding cheap shielded 
cables with at least 36 lines that are not significantly expensive (or 
have expensive connector requirements)

Jim