Thanks for the reply.
My IDE drive is about 2GB which is overkill and beyond the capacities of
CP/M 2.2. So I'm only using 20MB of the drive for this project. My system
uses Interrupts for Floppy but polling for the IDE.
In the mid 70's and early 80's I did lots of CBIOS work and never ran into
stack problems with CP/M. Maybe the code was simpler and I used fewer
Calls, Pushes and Pop's.
I am currently using a Private Stack for some of my CBIOS debug routines
since they are more stack intensive.
Did you find that you had to make any other changes to the
Blocking/Deblocking code other than the recommended CP/M 2.2 patches for
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org
On Behalf Of Chuck Guzis
Sent: Friday, January 30, 2009 7:29 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Stack Depth requirements for CP/M 2.2 CBIOS
On 30 Jan 2009 at 19:08, ROBO5.8 wrote:
I have rewritten my old systems CP/M 2.2 CBIOS to add
an IDE Drive.
I've run into a problem that has me stumped. Everything works as long as
don't try and copy or assemble a large Assembly
I will be going along fine and then out of nowhere I will see CP/M request
access to Drive "T". My debug info says SELDSK is requesting Drive
I have added debug code to all the CBIOS routines so that they report what
they are doing to the console (slow but nice).
I've gone through my code many times and tested each routine via an
debug monitor. I believe I have added every CP/M 2.2
patch (1-6 and
is specific to the CBIOS including those dealing with
What do you mean by "large"? I've run 2.2 with disks up to 20MB with
CP/M's stack can't be depended upon for much space at all. Since my
BIOS code was interrupt driven, every interrupt service routine
started with a change to a private "system" stack. I recall having a
lot of problems before doing that.