[sdiy] Xpander

[John Ames]

On 10/18/20, Tom Wiltshire <tom at electricdruid.net> wrote:
> Still, parallel comms is always going to be faster, and I like the
> “transparency” of using a shared RAM to get data from one system to the
> other. It’s quite neat, in a rather 1980’s way!
Yep. As long as you have to interface other stuff (RAM/ROM, I/O
peripherals) on a parallel bus anyway, there's little reason not to do
inter-processor comms that way too. (Especially if you can pull a
trick with CPUs like the 6502 or the 68000, which only access memory
on a certain phase or clock cycle, to give both the main and secondary
CPUs uninterrupted access to shared memory.)