Mail Archives: opendos/2001/02/15/23:04:52
On Fri, 16 Feb 2001 14:36:26 +1100 "da Silva, Joe"
<Joe DOT daSilva AT emailmetering DOT com> writes:
> Thanks for that, Bruce.
>
> I'll look up info. on the web re. Z-System (preliminary
> checks seem to suggest this is also called ZSDOS) ...
Hal's variant requires some
pretty specific hardware
drivers (it uses banked RAM),
but basic Z-System (with or
without ZSDOS, which is a
BDOS replacement) has a
standard-sized 2K CCP
(ZCPR 3.4) and is available
in an automatic version
(NZCOM) that loads over an
existing CP/M 2.2
installation. At this point
I'm pretty sure it's all
freeware.
>
> Yes, as you have indicated below, one of the main
> reasons it would be good to know the size of the
> memory below the CCP, is so as to determine
> whether or not a warm boot is required, when
> exiting an application.
Yup -- ordinarily you just
design the program either
to overwrite the CCP or not,
and that determines your
termination method. Of
course a warm boot works in
either case, unless you
screw up and write to RAM in
the BDOS or BIOS regions.
>
> Joe.
>
> > -----Original Message-----
> > From: Bruce Morgen [SMTP:editor AT juno DOT com]
> > Sent: Friday, 16 February 2001 13:35
> > To: opendos AT delorie DOT com
> > Subject: Re: CP/M Question
> >
> >
> > On Fri, 16 Feb 2001 12:43:59 +1100 "da Silva, Joe"
> > <Joe DOT daSilva AT emailmetering DOT com> writes:
> > > I hope a question about DR-DOS' predecessor is not too
> > > "out of place" here ... ? <g>.
> > >
> > > Anyway, I have read information about CP/M 1.4 and
> > > 2.2 (or was that 2.0?) that said the command processor
> > > (CCP) occupies 2K of memory ...
> > >
> > > Now, my question is this : Were there any versions of
> > > CP/M (or CP/M clones), in which the command processor
> > > (CCP) was larger than 2K?
> >
> > CP/M v3.x, aka CP/M+, had a
> > larger CCP implemented as a
> > disk file, just like CP/M-86
> > and DOS. Hal Bower's fancy
> > version of Z-System also has
> > no fixed CCP size limitation.
> > >
> > > BTW, the recent question about "total memory" is what
> > > has reminded me to ask about this, because, as far as
> > > I can tell, the only way to work out how much memory is
> > > available/free on a CP/M system, is to subtract the CCP
> > > size from the BDOS starting address ...
> > >
> > Actually, you just use the
> > BDOS call vector at 0005h
> > and round down to the
> > closest page boundary --
> > that's as high in RAM as you
> > can write to without
> > impinging on BDOS -- as long
> > as you terminate your program
> > with a warm boot (e.g. CALL 0
> > or RST 0), you can safely
> > overwrite the CCP's address
> > space because that warm boot
> > will reload the CCP from
> > disk and then jump to it.
> > You only have to subtract the
> > CCP size if you plan to use
> > or restore the CCP stack and
> > end the program with a RET
> > instruction instead of a warm
> > boot.
> >
> > > Joe.
> > >
> > >
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