Dec Rainbow prehistory

From: Tom Jennings <tomj_at_wps.com>
Date: Thu Nov 20 16:39:32 2003

On Thu, 2003-11-20 at 12:37, Geoff Reed wrote:

> >(Logically-speaking, the 8086 was an accessory to the Z80, whivch owned
> >all the peripherals.)

> I always found the Rainbow architecture kinda cool actually, when running
> in x86 mode the Z-80 functioned as a dedicated IO processor, freeing the
> X86 to run your programs without having to deal directly with the preipherals.

If I recall, performance wise they werent' bad! They had shared
*memory*, not all that much of it and weird semaphores I think, but it
suuure beats a shared IO port or other nasty hack. Actual overlapping
IO.

It wasn't possible with MSDOS, but you could easily queue up disk
writes/reads on hte Z80 side, and have the Z80 tell the 8086 only upon
error, etc.
Received on Thu Nov 20 2003 - 16:39:32 GMT