PET: Info on MicroTech PETDISK II and Madison Z-RAM

From: Dave Dunfield <>
Date: Tue Sep 14 15:44:23 2004

Hi Guys,

I recently acquired a PET 8032 which has a couple of interesting
add-on's ...


  This is an 8" disk system for the PET! - the controller card installs
  in the "edit" ROM socket (the EDIT ROM moves to the card), it also has
  it's own ROM, and is "hotwired" into several other PET signals via
  "flying leads"...

  I don't have any documentation for this system other than a single
  handwritten sheet which shows the connections (they match the way it's
  installed), an address of 59904 to start the system (this works)
  and a few commands such as !SYS to get a menu, and !LIST to display
  the directory (these also work).

  The two original MICROTECH diskettes both exhibit disk errors - looking
  at them, it appeasr that they have both sat in the continuously running
  8" drive long enough to wear visible groves at track 0 (really visible).

  I did find two other "backup" disks, which boot (SYS 59904) and enable
  the above commands.

  Lots of details I have not been able to figure out - can anyone provide
  more information on this disk system? Anyone have documentation?

2) Madison Computer Z-RAM

  This one I have full docs for - it's a Z-80 / expansion RAM board which
  fits under the monitor and connects to the PET via the 6502 socket (the
  6502 moves to the Z-RAM board).

  What I don't have is any software for it - it apparently runs CP/M, and
  should have come with a double sided CP/M disk (one side for 2031&4040,
  one side for 8050 drive) ...

  Anyone got the software or other material for this board?

++ Among the 8" diskettes that came with the machine are some which are
   labled as CP/M format - and I can't read a sensible directory using the
   PETDISK software - Perhaps someone ported CP/M to the PETDISK II / ZRAM
   combination? - If so, any idea how I would boot it? - anyone have this
   particular combination operating?

You can see pictures of the machine and these devices on my site (just
updated this afternoon).

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools:
com             Vintage computing equipment collector.
Received on Tue Sep 14 2004 - 15:44:23 BST

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