Writing single density disks on a PC?

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Mon May 19 13:30:01 2003

>To: cctalk_at_classiccmp.org
>
>Ok, I want ot generate some disks for my Model 4 on my PC, BUT some of the
>disks I want to regenerate are mixed single and double density ... any
>suggestions?
>

Hi Geoff
 If it is done a track at a time, you can deal with it
by using the low level disk access functions of the BIOS.
You do have to have a disk controller that supports
single density ( not all do ). There are a few articles
around that describe setting up the DMA ( needed for floppies )
and the disk controller, as another option. I've found
this method to sometimes be machine dependent so if
you can get by with the standard BIOS calls, that is
a better way.
 If you can read Forth, I can send you some code I wrote
to write tracks for my Olivetti M20 ( Z8000 machine ).
I don't have a controller that does track 0 that is
single density but you can get the idea of how to handle
the controller and DMA. The other tracks are double
density ( 360K drives ). You also need a compatible
drive. You can't use a 1.2M drive to write single density
at all and double density is not properly done so
it will most likely fail to read reliably( a track width
issue ).
 It may also be that your machine is supported by things
like 22DISK. Have you tried this?
Dwight
Received on Mon May 19 2003 - 13:30:01 BST