Re: interface card for the PC to read & write apple2e floppies

[Linards Ticmanis <ticmanis@coli.uni-sb.de>]

william strutts wrote:

> The Floppy drives used in the Apples used a format called
> GCR(??) which is a multispeed format  unlike the standard
> format of the PC which is MFM.  You can't read a Apple
> disk using a standard PC drive mechanism.  

1.) The 5.25" Apple format is GCR but it isn't multispeed. Only the
Apple 400K and 800K 3.5" formats are multispeed.

2.) The Mechanism isn't the problem in either case. You can get
multispeed in a monospeed mechanism by varing the _data_ speed instead
of the drive speed. The Catweasel controller can do this. Also e.g.
Commodore 5.25" drives did this by default, to fit more data on the
outer tracks, so it's a proven concept.

However the PC floppy controller can do neither MFM nor variable data
speed (well it does have 4 (?) different data speeds, but it can't
vary the data speed in the small steps needed for 800K disks).

-- 

Linards Ticmanis

 The Master said, "The business of laying on the colors follows the
preparation of the plain ground."