"CP/M compatible" vs. "MS-DOS Compatible" machines?
ajp166 at bellatlantic.net
Sun Feb 3 06:31:34 CST 2008
>Subject: Re: "CP/M compatible" vs. "MS-DOS Compatible" machines?
> From: "Roy J. Tellason" <rtellason at verizon.net>
> Date: Sat, 02 Feb 2008 20:54:28 -0500
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>On Friday 01 February 2008 03:36, Jim Battle wrote:
>> Also, people did *plenty* of ugly stuff to save a few bytes back then,
>> as you know. RST1 isn't particularly ugly anyway. And if for some
>> reason one did find it unpleasant, you could use a macro to make it to
>> your liking.
>> we agree. :-) I had a vague recollection of a faint memory of hearing
>> third hand that CP/M was ported to some heathkit machine, but that the
>> machine already had a ROM in low memory, and so instead of "CALL 0005H",
>> one had to use "CALL 2005H" or some such. CP/M programs could be very
>> easily reassembled/patched for this, but stock CP/M binaries wouldn't
>> work. rather than repeating this slanderous story, I didn't bring it up
>> and pretended it was just a supposition. ooops, but now the cat is out
>> of the bag.
>I believe the H-8 did indeed have a ROM at low memory. Never worked with that
>machine, though. There were also some TRS-80 boxes that I seem to recall
>having a need of a special version of CP/M as well.
TRS80 (original) had the first 16k used for rom, keyboard and videoram,
Therewas a hacked version of CP/M for it that moved page 0 (first256bytes)
to something like 4200h and TPA started arond there too. The problem was
none of the usual CP/M programs were assembled/compiled to start at 4200h
(norm was 0100h) and even if the trs80 was full of ram you were under 48k
which was ok but bigger CP/M apps like MSBASIC used some 24K of that or
more. Not a popular implmentation.
>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
More information about the cctalk