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Date   : Fri, 07 Jun 1991 06:42:52 GMT
From   : uhccux!munnari.oz.au!bruce!monu0.cc.monash.edu.au!monu1.cc.monash.edu.au!rjl@ames.arc.nasa.gov ( r lang)
Subject: Re: CP/M disk formats (was Re: CPM to DOS exchanger)

In article <822@spam.ua.oz>, dcook@spam.ua.oz (David Cook) writes:
>    While on the subject of disk formats, are there any programs
> that will read Microbee 3.5" CP/M disks. As far as I am aware, the
> Microbee (an Australian designed and built CP/M machine, which also
> had some graphics support, until the company went broke :-( )
> is the only CP/M machine that uses 3.5" disks, which hold 390K.
Microbee still exists, but to my knowledge is not making CP/M
machines.  Microbee was bought out a few years ago by the
Serafini (sp?) brothers who run MicroHelp in Brunswick, Victoria.

> While I'm asking, I'll be really optimistic, and ask if there
> are programs for the Microbee which will read IBM 3.5" disks 
> (somehow I _really_ doubt it :)
Yes.  FBN Software which wrote PC-Alien also wrote Bee-Alien which
was sold by Microbee.  I bought a copy of this and it mostly works
(my version won't format IBM 5.25" 360k disks, but will read them
correctly).  There are some 3.5" MSDOS formats listed, but I haven't
tried them.

I have also written my own program to read and write IBM disks -
this will handle 5.25" 360k and 3.5" 720k.  It is known to work
on a 54k, 128k and 256k Microbee.  Since CP/M has an ambiguous 
file end, copying to CP/M and back to IBM will usually give you
some trailing garbage on a file (after a ^Z).

If you send me a 3.5" disk with return postage, I will put on it
a copy of Kermit-80 4.11 for the Microbee.

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 ...

> My guess would be that the disks are single sided, double
> density with either 5 1k sectors per track or 10 512btye
> sectors per track, with first 2 tracks reserved for system.
3.5", 10 512byte sectors per track, single sided, 390k
3.5", 10 512byte sectors per track, double sided, 780k
In both formats tracks 0 and 1 (both sides) are reserved for system.
I have the correct DPB entries and skew table if anyone wants them.

Russell Lang   Email: rjl@monu1.cc.monash.edu.au   Phone: (03) 565 3460
Department of Electrical and Computer Systems Engineering
Monash University, Australia

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