Ideas for a simple, but somewhat extendable computer bus

[ben]

On 11/20/2017 8:41 AM, Tapley, Mark via cctalk wrote:
> On Nov 19, 2017, at 11:54 PM, Chuck Guzis via cctalk <cctalk at classiccmp.org> wrote:
> 
>> So we agree on parallel standard buses, that STD bus is a strong
>> contender with varied processor base.
> 
> 	Catching up late, sorry if this is an old question, but what did the Digital Group computers use? My recollection is that they offered cards with 6800, 6502, 8080, and Z-80 CPUs on the same bus, and that part of the system seemed to work reasonably well.  (At least, the Digital Group system complaints I read seem to center on the PhiDeck mass storage system not the CPU/memorylperihperal bus.)
> 	There is a nice website at: http://www.bytecollector.com/dg_cards.htm which seems to show cards with not a whole lot of pins to connect to the bus - maybe 36 pins on the visible side, though the card is definitely 2-sided so probably 36 more on the back side?
> 
I think they also had the chip that did the pdp8 instruction set too.
That also brings up the other point, what software did they have?
Ben.
I can see it now, a pdp 8 time sharing emulating a 6502 emulating a 8080. :)