Writing single density disks on a PC?

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Mon May 19 14:02:00 2003

> >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?

On Mon, 19 May 2003, Dwight K. Elvey wrote:
> 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.

To do either single density, or the special data address marks, you will
have to go below the BIOS level (13, 1E). not especially hard to do, but
there can be a few minor portability issues.

> You do have to have a disk controller that supports
> single density ( not all do ). There are a few articles

look for the 37C65 chip; but there are some others, and even the stock
5150 FDC board can be MODIFIED for SD.

> 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?

Try Hypercross/PC-Xzap from Hypersoft.
I'd like to hear from anybody who has SUCCESSFULLY used 22DISK for
anything other than CP/M, or used ANY commercial product for SD.
Yes, Catweasel or Option board THEORETICALLY could do it.
Posters about any product that "can do it", but don't differentiate
between "CAN DO" and HYPOTHETICAL POSSIBILITY can go F themseves.
(During the life of my products, I constantly competed with rumored,
but non-existent, capabilities of some products)
Received on Mon May 19 2003 - 14:02:00 BST

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