[sebhc] h17 and h8d disk images
Barry Watzman
Watzman at neo.rr.com
Wed Sep 1 20:44:11 CDT 2004
I may be having a "bad memory day" -- it's been 20 years, after all --, but
that's not my recollection. The Microsoft stuff for HDOS, of course, only
worked under HDOS. For CP/M there was a "vendor" byte in the CP/M serial
number that an applications program could check, and all of the Microsoft
software for CP/M (sold by Heath) did check that and wouldn't run unless it
had one of {I think} 3 values, the values assigned to Lifeboat (which sold
CP/M for Heath systems, for a while), Heathkit and Zenith Data Systems.
But I don't believe that we played any games with the memory mapping in any
of the software that I was responsible for (which was all of the systems
software under CP/M for the H-8 and H-89).
-----Original Message-----
From: sebhc at sebhc.org [mailto:sebhc at sebhc.org] On Behalf Of Dan Lanciani
Sent: Wednesday, September 01, 2004 9:31 PM
To: sebhc at sebhc.org
Subject: Re: [sebhc] h17 and h8d disk images
Dave Dunfield <dave04a at dunfield.com> wrote:
|Does anyone know if CP/M just switches to RAM once, or does
|it toggle between ROM and RAM (say to access ROM functions)?
The operating system proper just switches to RAM; however, various
CP/M applications sold by Heath were buggered to work only on Heath
hardware. They did this by switching the ROM back in and checking
for some known bytes. I have a vague memory that something that came
with the OS did this as well.
Dan Lanciani
ddl at danlan.*com
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