Message-ID: <01FD6EC775C6D4119CDF0090273F74A4021F65@emwatent02.meters.com.au>
From: "da Silva, Joe" <Joe DOT daSilva AT emailmetering DOT com>
To: "'opendos AT delorie DOT com'" <opendos AT delorie DOT com>
Subject: RE: CP/M Question (#1)
Date: Fri, 16 Feb 2001 14:36:26 +1100
MIME-Version: 1.0
X-Mailer: Internet Mail Service (5.5.2448.0)
Content-Type: text/plain
Reply-To: opendos AT delorie DOT com

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) ...

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.

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.