15 Nov
2007
15 Nov
'07
5:27 a.m.
On Thursday 15 November 2007 00:04, Chuck Guzis wrote:
On 14 Nov 2007 at 23:36, Roy J. Tellason wrote:
Maybe it was some fairly negative comments about MP/M I was remembering...
Multi-user in an 8-bit context doesn't sound
real terrific to me, for
some reason, though I don't see a problem with multiprocessing if it's
done right.
It could be remarkably good, but you have to work within the
limitations of the architecture. The x80 CPUs didn't have any good way to
dynamically relocate code and data
and had a fairly small addressing space.
I guess that depended a lot on how you coded things. The biggest single thing
that jumps out at me being absolute addresses, and I guess that it's
possible to avoid those to an extent. And if stuff was modular enough you
could make some small but effective modules that wouldn't take up all that
much room. Wasn't that what ZCPR was trying to do? At least that's the
impression I'm left with after having browsed some doc files, and that
wasn't recently...
We simply went to a (pcode-type) interpreter that
serviced all of the
users. It cut down on redundant code and since we were executing
BASIC programs, the speed penalty wasn't too awful.
Ok.
I received a note last week from a one-time customer
in Japan who
mentioned that they were talking about phasing out the old code
they'd written back in the 80's for the system we wrote in 1979 for
an 8085 (supporting 5 users) and later ported to SCO Xenix. He
remarked that they'd added to the programs over the years with no
problems. This is more than 20 years after the company offering the
language went out of business.
That's impressive!
I've still got the source code somewhere.
For the 8085? I'd be interested in seeing that, if that would turn out to be
convenient. I've always sort of liked that chip for some odd reason. What
else in terms of hardware did the system have that you ran this stuff on?
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin