Date   : Fri, 07 Jun 1991 14:02:23 GMT
From   : cis.ohio-state.edu!zaphod.mps.ohio-state.edu!hobbes.physics.uiowa.edu!iowasp.physics.uiowa.edu!syswtr@ucbvax.Berkeley.EDU
Subject: Re: CP/M disk formats (was Re: CPM to DOS exchanger)

In article <1991Jun7.064252.13117@monu1.cc.monash.edu.au>, rjl@monu1.cc.monash.edu.au
(    r    lang) writes:
> In article <822@spam.ua.oz>, dcook@spam.ua.oz (David Cook) writes:
> Clarence Wilkerson writes:
>> If the 3.5" disk is physically compatible with ibm pc type
>> drives, then you can hack a set of parameter tables to match
>> them and use 22disk, a shareware program that runs on a PC.
> I have tried this and it didn't work.
> I have two theories, neither has been tested.
> 1. Microbee disks have 10 sectors and the intersector space
>    is shorter than specified in the Western Digital data sheet.
>    The PC may not like this short space.
> 2. I think (but am not sure) that the sector header information
>    is marked side 0 for both sides of the disk.  
>    If the PC insists that side 1 is marked as side 1 ...

 On item 2:

  The SMC floppy controller on the SB180 (a '765 look-alike) is capable
of reading diskettes that have the side bit in the sector header wrong.
I don't know if the NEC or Intel chip acts the same, but if so the 
following may help:

       Write command:
                       Command
                       Unit/Head (controls hardware lines)
                       Cyl
                       Head (controls what is to/from disk)
                       Record
                       Size
                       EOT
                       GPL
                       DTL

  On the FDC9266 setting the 'Unit/Head' bit to side one and the 'Head'
byte to side zero does work.

Willy