Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!mephisto!udel!rochester!ken
From: ken@cs.rochester.edu (Ken Yap)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Xerox -> IBM file convers
Message-ID: <1990Feb15.043015.12936@cs.rochester.edu>
Date: 15 Feb 90 04:30:15 GMT
References: <90021400170529@masnet.uucp> <25d9d7d8.1e8e@polyslo.CalPoly.EDU>
Reply-To: ken@cs.rochester.edu
Organization: University of Rochester Computer Science Department
Lines: 25
Address: Rochester, NY 14627, (716) 275-1448

|>In a previous article I wrote:
|>>There are at least two commercial products that will let you read
|>>Xerox and all other CP/M disks on a pc.  One is Uniform-PC, the other
|>>is Media Master.  I don't have the coordinates handy for the
|
|>To which Mark Freedman responds:
|>   I'm quite certain that the drive controller in the PC won't handle
|>single-density formats. It's a hardware limitation designed into the
|>board.
|
|Yes, of course that is true.  I exaggerated sligtly.  I figured that
|given the distance back in history that it has receded to, it really
|doesn't matter that much.  It also won't read the hard-sector formats 
|such as Heath and North Star.  Uniform-PC will also read
|odd DOS formats such as Rainbow 80T SS and Sharp 3.5" 40T.

No, no, wait a moment, don't fold your cards so fast. The manual for
the 22DISK program by Sydex, which is for reading CP/M disks on MS-DOS
says that the IBM floppy controller can read 3740 format recorded
disks (which is what single density means I assume).  I also looked at
the data sheet for the 765 floppy controller chip and indeed it has
this mode.  But the catch is this: you have to make a simple hardware
patch between the controller to the demodulator chip (?) to enable this
mode.  The details of this patch are in the 22DISK documentation.
22DSK is in the Simtel archives and slave archives too, I presume.