"CP/M compatible" vs. "MS-DOS Compatible" machines?

Roy J. Tellason rtellason at verizon.net
Sat Feb 2 16:47:15 CST 2008

On Tuesday 29 January 2008 16:33, Joshua Alexander Dersch wrote:
> scheefj at netscape.net writes:
> > In the early-mid 80's a program was "well behaved" if it did it's I/O
> > thru DOS calls. Those programs would run on just about anything.
> Were there similar problems in the CP/M world?  That is, was it commonplace
> for there to be CP/M programs that bypassed CP/M BDOS calls and wrote
> directly to a specific machine's hardware?  Seems like CP/M developers were
> more disciplined in this fashion, but maybe it's just because in the CP/M
> arena there were so many different pieces of hardware it was the only way
> to do it?  (Whereas with IBM, the PC was seen as more of a reference
> standard, even if it wasn't really that way in the beginning?)
> I'd be interested to hear opinions from people who were there at the time,
> since it was a little before my time.

There was stuff written for specific hardware (floppy formatting code for one 
fairly typical example),  and then there was stuff that got patched for a 
specific machine,  which more often tended to address things like video 
attributes and similar stuff -- I know that the copy of WordStar I used to 
use on my Osborne Exec was patched all to hell.  :-)

So was the directory listing program I used,  "sd".

Other code that often needed to be modified for specific hardware or machines 
were comm stuff,  which more often seemed to have a bunch of "overlays" 
available for each machine,  so that things could address the serial port (or 
the PMMI S-100 bus modem) properly.

I probably have piles of this stuff in my old bbs files area,  if there's much 
interest in it.

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

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