It might be a bit of a bottleneck ;D. I'd also doubt you could have this many devices hanging off the same bus (at the electronic level, each card's outputs would need to supply enough current to drive 65535 cards inputs).Kemp wrote: That's a really nice idea, though I can imagine some issues with cards wanting the bus at the same time on a 65536 slot machine.
You'd actually need a hierachy of buses (similar to PCI):
1 Level 1 bus -> 16 bridges to 16 level 2 busses
16 Level 2 buses -> 16 bridges to 16 level 3 buses per level 2 bus
256 Level 3 buses -> 16 bridges to 16 level 4 buses per level 3 bus
4096 Level 4 buses -> 16 slots per level 4 bus
With this arrangement you'd be able to place the cards so that most traffic only involves one level 4 bus, with at least one CPU card in every group of 16 slots to minimize bus traffic (and IRQ latency).
Worst case would involve the level 1 bus, 2 level 2 buses, 2 level 3 buses and 2 level 4 buses. If you assume 100 nS latency for each bridge and 50 nS latency between a card and it's level 4 bus, then you'd be looking at access times of 700 nS worst case and 100 nS best case.
Cheers,
Brendan
