[Coco] 8 slot multi pak

[Dave Philipsen]

Yes, that's possible.  I have some old passive backplanes that were used 
for an animatronics system that used a 6502 processor at 1 MHz as the 
main board and the CPU card with just a single set of buffers would run 
8 or 9 other cards on the backplane.  The backplane fit into a 19" rack 
and I don't believe there was any kind of termination on the end.  
Literally hundreds of these card cages were made and used about 12 hours 
a day, 365 days a year and some are still running today (since 1977) and 
have had no problems in that regard.  Some expansion cards had 6821s, 
some had 6850s, that sort of thing.  The backplane PCB was double 
thickness - .125".

Dave


On 1/18/2017 1:18 AM, RETRO Innovations wrote:
> On 1/18/2017 12:44 AM, Dave Philipsen wrote:
>> I think you could probably drive 8 slots with a single set of 
>> buffers.  Just make sure the buffers have a high fanout.  I think 
>> some buffers can do 20 or more TTL loads on fanout.  And you might 
>> also want to experiment with termination on the end of the lines.
> I meant to also note that the capacitance might be an issue, but 
> forgot to add that before sending.  TI and S-100 bus machine shave 
> 8-12 slots, but most include buffers on each card to deal with the issue.
>
> Jim
>
>