Re: Reading non-MFM disks in PC without special controller

From: Hársfalvi Levente (
Date: 2001-11-13 13:27:48

Hi Ruud!,

> Please see the bottom of

No, I mean some simpler hardware.

As I see the Catweasel must be kind of a bitstream capturing device (ie.
it is a standard ISA card that probably captures / writes one whole
track to / from its onboard RAM, that your PC program can reach through
I/O ports).

Instead that - let's suppose a small microcontroller based board on the
floppy cable itself. It could be a 'through' interface, ie. you connect
the floppy drive to its one end and connect the interface to the PC
floppy controller with the other. The uC would be programmed not to
interfere with any regular floppy operation - but if it received a
special MFM sequence, it hooked the floppy controller signals for

The idea is to leave all usual tasks to the PC (select head, track, turn
on the motor etc.), and instead of buffering, rather let the
microcontroller generate a 'fake', long MFM sector (containing one full
track), on the fly, from the raw bitstream it is receiving from the

I guess it could work similarly into the other direction. ...Provided
that the main idea is correct.

I had this idea since a long time, I just haven't known such vital infos
that I just read in the article... (and also, I probably still couldn't
write the neccessary PC code myself).

(Heh... If it worked... Imagine reading a full 1541 disk in hmmm... 35*
(60/360 + 0.05) = 7.58 sec ;-) in a regular 5.25 HD drive... (and I was
probably too pessimistic about the floppy seektime).

Best regards,


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