OT: A call to arms (sort of) - test-drb@ccmp.vtda.org

3 Jul 1999

You may indeed be onto something here, Allison, but the ISA is no less
general in its inherent qualities than the S-100, and I'd submit that a
major case for the S-100's popularity for non-8080 applications was the
ready commmmercial availability of numerous desirable functions at
reasonable prices.  That's how the ISA occurred to me.

Aside from that, a general purpose not processor-biased architecture would
provide a few control signals, e.g. IORD, IOWR, MEMRD, MEMWR, maybe a couple
of clocks, probably one fairly fast one suitable as a dot clock for a video
circuit, and one slower, suitable for bus transaction timing, a few
interrupt and DMA support signals, and a couple of dozen address lines.
Parity and maybe a "tilt" line would be handy, as well as a wait signal.
Most busses have these signals in one form or another.

The key element for generalized development, though, is whether or not you
can afford to buy the functions you don't want to build right away.  Don't
you agree?

Dick

-----Original Message-----
From: Allison J Parent &lt;allisonp(a)world.std.com&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Saturday, July 03, 1999 9:35 AM
Subject: Re: OT: A call to arms (sort of)

...
 <agree on what your goals are?  Some of these
suggestions indicate that
<certain people like certain things, but there's really been no discussion o
...
 <why one might want to use one or another.  In the
absence of
<goals/requirements, there can be no analysis or design.
<
<Does anybody know where this is supposed to lead?

To yet another iteration of the last 30 years of computer and bus design.
 <snip>
...

The ugly exception!  This doesn't make it good, only the odd exception
for unexplainable reasons despite being primarily a 8080 bus!

S100      8080, 8085, 808x, 80x86, z80, z180, LSI-11, AM100, TI9900, 6502,
          6800, 6809, 6800x

How is it that one of the ugly busses stands out like this in history?
My cut is that the very flavor of an experimentors "hobby" bus was the
draw.

Allison