Unknown S100 system
Roy J. Tellason
rtellason at verizon.net
Fri Sep 21 15:35:41 CDT 2007
On Friday 21 September 2007 16:01, Chuck Guzis wrote:
> On 21 Sep 2007 at 14:07, Roy J. Tellason wrote:
> > I wonder why they went with that part? I seem to remember some others
> > that used it as well, though specifics are not coming to mind at the
> > moment. I have a bunch of those on hand, and think about doing
> > something with them from time to time. It's a fairly easy chip to use,
> > with an eprom and a ram chip and a single address latch, I just haven't
> > decided yet what I'm gonna do with it.
> Compupro 85/88 board; my own Durango F-85 and a host of others. If
> you can find some of the support chips (8155, 8755), the parts count
> can be very low, given the vintage of the 8085.
Compupro was the one that was hanging out there at the edge of recall...
I may have some of those support chips, too. 8155 (and 8156, which is the
same part with a different select pin polarity if I'm remembering right)
sound real familiar. I have the 8085 Cookbook and a few others that Sams put
out, one covering this text editor and assembler (which I didn't really care
for, but...). No interest in the ROM-based 8355 and I've never seen the
EPROM-based 8755. The relative i/o and RAM address mapping of those parts
gets a little confusing, though, and the book is a bit less clear than it
could be on that aspect of it.
> I suspect that the reason 8088/8085 pairs were fairly common in
> comparison to Z80/8088 pairs was that timings and buses on the 8088
> and 8085 are *very* similar and getting them to work with 8000-series
> peripherals was very easy. IIRC, one could even replace an 8085 with
> an 8088 (assuming you were restricting it to 64K addressing) with a
> minimum of "glue". Both multiplex the data lines on A0-A7 the same
I'd never really looked at the 8088 and later parts all that much, or to that
level of detail.
> I suspect it might be easier to substitute an NSC800 for an 8085 if
> Z80 functionality is needed than trying to shoehorn in a Z80.
That's another part I have no familiarity with at all at this point in time,
though of course I've heard of it.
With regard to what little programming I've done, the thing I like most about
the z80 is relative jumps, which makes relocatable code easy to do. The
other big deal is the alternate register set and the index registers, which
I really haven't used all that much.
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