CP/M-8000

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Mon Sep 16 12:59:00 2002

Hi Chris
 I spent quite a bit of time looking at the stuff from
the web site on the CPM-8000. It looks like the CPM.SYS
in the cpm8k11 stuff is built specifically for the
M20. It was made with the symbol table so I was able
to find the various tables.
 I don't think the fellow that did this implementation
really had a solid grasp of a boot process but what they
have done should work. There is no reason why what they
call CPMLDR.SYS couldn't have been a slightly modified
CPM.SYS with a simple loader added ( like more traditional
CPM's ).
 If you look, you'll see that in one place ( I forget where ),
they have a compiler flag called TRANSFER. It would seem that
they had, in fact, connected a 8 inch drive to a system as the
next drive after the hard drive. They used this as a transfer
system.
 The disk, that the .img files were from, was built as
though it were for this setup. It was not a bootable
disk. There is quite a bit of information on building
a boot disk in the various files that contain the tables
T0S0, T1S0 and T1S1. These are the main information
involved in creating a boot disk. My understanding of
T0S0 leads me to think that the one they have is not
correct but may have still worked. I believe we can
continue to just use the unaltered T0S0 that is on the
disk, formatted by the M20. We can just build the bootable
image on one of these disk. We don't need to get too carried
away. Once we've built a disk that boots, we can add
one file at a time to a different disk and transfer them
using the second drive. This way, we only have to deal
with the directory on the CPM for one file at a time.
This simplifies transfers but may take a little extra time.
Still, we wouldn't have to deal all that much with disk
space allocation.
 I'm going to fiddle with trying to build up an image
but I'll only be able to do this in the evenings this week.
Next weekend I'll be off visiting relatives.
 I converted another RAM board to 128K. It now boots to
384K :) It was one of the two B/W memory boards that
I have. It wasn't as simple as I thought. Changing pin 8
from +12V to +5V was just a simple jumper change but
Pin 9 had connections inside to an internal power plane.
This time, rather than lifting a pin on the chips, I
lifted one of the socket pins. I used a little quick setting
epoxy to insulate the board pin 9 from the socket pin
that I bent out to the side. On these boards, there was
at least, a nice jumper hole to connect this additional
wire to ( it even looks like they had intended it to
be jumper configured but the internal plane connections
kept one from doing that ). It took me about 4 hours
to do one board. I could have done it faster if I didn't
want to save the IC's. Just clipping the IC out and
pulling the pins is a lot faster than removing the entire
IC, intact. It is a lot safer for the board but I
just can destroy working chips.
 Anyway, do you know of any issues that I should look out
for in creating a boot disk from these files? I haven't
seen anything that looks like a show stopper.
Dwight
Received on Mon Sep 16 2002 - 12:59:00 BST