Question about Intel disk formats

From: Vintage Computer Festival <>
Date: Wed Jun 20 22:31:53 2001

I've got some 8" disks that are apparently double density (the
manufacturer label says so). I thought they were Intel ISIS formatted
disks (which Eric Smith said would make them M2FM and uncompatible with
anything other than an Intel MDS development machine) but I'm not so sure,
since I can't seem to access any on the two Intel MDS systems I have set

Both machines have Shugart 801 drives in them, and after doing some web
research, I've come to find out they are single-density only. This would
probably explain why I am not able to access these disks on these

The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.

However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they

If they are in a standard DD format, and I have a computer that can boot a
DD CP/M system master, could I then pop these disks in the drive and do a
DIR to see if I get a directory?

For those who've used these before: when I put any of the disks in
question in the drive, the drive seems to seek for a few seconds, then
goes off for a split second, back on again for half a second, then off
(and the system crashes). The normal boot sequence for a (single density)
system disk is, upon reboot the disk seeks for a few seconds, then stops
for a split second, then starts seeking/reading for a few more seconds and
the ISIS prompt comes up.

It seems the system is trying to read the double density disks and just
not seeing anything intelligible and crashes. With single density
non-system diskettes, the machines will come up with something like "NOT A

Suggestions appreciated.

Sellam Ismail Vintage Computer Festival
International Man of Intrigue and Danger
Received on Wed Jun 20 2001 - 22:31:53 BST

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