To: opendos AT delorie DOT com
Date: Fri, 16 Feb 2001 03:55:11 5
Subject: Re: CP/M Question (#1)
Message-ID: <20010216.040105.-4038533.3.editor@juno.com>
X-Mailer: Juno 5.0.27
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Juno-Line-Breaks: 0,2-102
From: Bruce Morgen <editor AT juno DOT com>
Reply-To: opendos AT delorie DOT com


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.
> > > 
> > > 
> > ________________________________________________________________
> > GET INTERNET ACCESS FROM JUNO!
> > Juno offers FREE or PREMIUM Internet access for less!
> > Join Juno today!  For your FREE software, visit:
> > http://dl.www.juno.com/get/tagj.
> 
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.