Date   : Wed, 26 Sep 1990 09:10:21 GMT
From   : pacbell.com!pacbell!ditka!qiclab!techbook!fzsitvay@ucsd.edu (Frank Zsitvay)
Subject: CPM Companion

In article <9009191229.aa09295@crdec8.apgea.army.mil> mdgoodma@CRDEC8.APGEA.ARMY.MIL
(Mack Goodman) writes:
>Could someone send me a brief description of what this device
>is, and could it be useful for me.  I have a Northstar Advantage.
>This device is called " CPM Companion 2.2 "  It is a black box
>with a couple of ports on it and a "edge" connector?
>
>Private replys may be most appropriate,  Thanks in advance.
>
>Mack Goodman

  i apologize for this seemingly unseemless thread, but the local
piece of s--t mail system here keeps barfing this mail message back
to me, which really doesn't make a whole lot of sense since we
had this thread going in mail for the past 2 or three cycles.  (i know
it's a local thing because the system barfs the message within 10 seconds
of sending it.)

now, back to the discussion....

when this thread was so rudely interrupt by a flakey mail system, 
Mack Goodman wanted to know how to get his Companion (a cp/m 2,2
machine) up and running, mainly because his northstar advantage
didn't know what to do with a soft sectored disk.

---
   well, the companion would be able to read and write soft sectored
disks with no problem, assuming you could find a boot disk for it.
if you can find such a disk, then you would be home free.  just gut the
ns advantage and use it's disk drives for the companion, and term software
on the ns itself.

   whether a system uses hard sector or soft sectored disks is mostly
a function of the controller.   check the controller in the advantage and
see if it uses a 179x or a 765 chip.   if it does, then it's a matter
of software.   if it uses discrete logic, or one of the 177x controller,
then you're out of luck.   i say 179x and 177x meaning the series, as there
is a 1791 and a 1793.  same for the 177x series.  the differences is in the
interface electronics, but both are the same from a software point of
view.

   if you are knowledgable about cp/m and assembly language, you can do
one of two things...  either configure cp/m for the companion, or rewrite
the bios routines in the advantage to allow the use of soft sectored
disks.   and, if you can find a bios listing for a kaypro or other good
cp/m machine, you could hack that until it works.   this is basically
how products like uniform work, they replace those sections of the bios
with code similar to the machine it's trying to emulate the disk format.

   for the advantage, if it uses a 179x controller chip (like most decent
cp/m machines do) then all you would need are the addresses of the controller
ports.   get a bios listing for sometthing like a kaypro, and just change
the addresses in the bios to point to the right place.  do this in ram
with ddt and sysgen it onto a disk, and you would have yourself a boot disk
for any floppy you want.

   for the companion, you would do something similar, except you would have
to find the ports addresses, and since you don't have any docs, that can
be somewhat difficult.  what i would do is open the machine, and look
at the circuit board traces to see what address the controller chip
is located, and go from there.

   once you get a disk system working on the companion, the rest is easy,
since then you could do your system exploring via software on the
machine itself, which is much easier in my opinion from doing it from
circuit board traces.

   where are you located at??  you might be able to find a cp/m machine
cheap, and you wouldn't even need to do some serious hacking to get it
working, either.    unless it is something you like do, which is why
i go through this sort of torture.  (one man's pleasure, another man's
pain...)

   i don't suppose a month goes by where someone offers their cp/m machine
to me for the price of hauling it away.  if you look, you can find some
real bargains out there...


-- 
fzsitvay@techbook.COM - one of these days i'll get it right...

Version 2 of anything is usually the version that works.