Scott,
Like many of the time performance a was a thing...
Exity was only one and that was later.? IN 1980 I setup to make the meanest
z80 system I could using 6mhz Z80s that were appearing.? Basic design was?
remarkably simple, 4 z80 CPUs each its own board with 64K of ram and a bus
access protocol (S100 BUS) to share data or resources? (disks, Serial IO and
printer).? ?All of the resources were smart as in each had local Z80, 8085, 8749
(printer buffer) to perform tasks.? The goal was to share IO and offload tasks like
find a file or spool to printer.? That meant doing surgery to CP/M to split out parts
so that the master cpu (server) did end up with all the work (Bios stuff or BDOS)
or running a full copy of CP/M on each or the four cpus.? Lots of interprocess
communications, interrupts, plus a little foreground background on each.
Basically the box was a bunch of networked (via parallel bus) cpus and service
providers.
In the end while I ran it for years and proved useful a single faster cpu was
not burdened with as much overhead.? It also proved CP/M based software
while unaware of the multiple cpus was the actual problem as it was unaware
of resources that could be useful.? The hardware was doable and all but software
had to catch up.? Multiprocessing and time slice was the realm of PDP-11 and VAX
or other heavy iron, the Z80 could but the OS was not yet there.
CP/net and MPM made some things easier? but the the existing applications
software was still built for 64K (or smaller) spaces and had no idea of extensions
or how to use them.? That required something Unix or later and all of the seriously
needed larger memory space.
Allison
