Date   : Sun, 22 Mar 1987000:57:00-MST
From   : ucsdhub!jack!man!crash!mwilson@SDCSVAX.UCSD.EDU (Marc Wilson)
Subject: SUPRBDOS use of z80 registers?

In article <15244@amdcad.UUCP> bandy@amdcad.UUCP (Andy Beals) writes:
>In article <1987Mar19.141504.21625@gpu.utcs.toronto.edu> edwest@gpu.utcs.toronto.edu
(Dr. Edmund West) writes:
>>  Incidentally, I got started on all this when I tried to install
>>SUPRBDOS (the public domain replacement for DRI's BDOS) and discovered
>>that the HDC driver trashes the IX register SUPRBDOS is using.
>
>Boo on SUPRBDOS for doing that.
>
>CP/M-80 is an *8080* operating system.  If your BIOS or BDOS uses any of
>the z80 register set, it MUST save them or else it will break many many
>programs.  This is my biggest gripe with the turkey who did the bios and
>roms for the Osborne-1.  (grumble grumble)

     I have never had *anything* "break", although both my BDOS
( SUPRBDOS ) and my BIOS use the Z80 register set.  I would submit to you
that with the number of Z80 CP/M machines around vs. 8080 machines, any
program that assumes that the extra Z80 registers are inviolate is asking
for trouble.

     Why must the BIOS/BDOS save the registers?  You don't expect HL, or BC
to be preserved after a BDOS call, why should IX or IY be?

     BTW... has anyone noticed the following with SUPRBDOS?  Occasionally,
it will report 2 files with the same name on the same disk, although there
is only one.  It's never fatal, and never seems to show up unless SUPRBDOS
detects that you've swapped disks.
-- 

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Marc Wilson   ( mwilson@crash.CTS.COM )
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