Using a Commodore 1541 drive with a PC via USB

Veit, Holger holger.veit at
Wed May 25 02:17:10 CDT 2016

Am 25.05.2016 um 06:45 schrieb drlegendre .:
> It may, in fact, be possible - with custom ROMs - to use the 1541 for other
> formats. But it's telling that no one, so far as I know, has ever managed
> to create software to 'tween the various 5-1/4" floppy formats, using the
> 1541 transport & hardware.
The 1570/71/81 drives have a dedicated WD controller chip for the 
compatible MFM formats.
I doubt that even with a custom ROM it would be possible to cleanly 
bit-bang MFM instead of GCR to the
data/clock port to the drive. With the GCR encoding home-grown by 
Commodore there were no tight
restrictions to the data rates that are enforced by IBM compatible 
formats; they could invent any rate
their hard- and software could manage.


> On Tue, May 24, 2016 at 8:43 PM, Cameron Kaiser <spectre at>
> wrote:
>>> A fellow has made up a nice adapter to read and write Commodore disks on
>>> a PC via USB using a 1541 drive.
>>> The thing that jumped out at me is that this is a 5 1/4" drive that
>>> reads and writes via USB.  Anyone want to comment on whether the
>>> floppies it accesses would be useful other than on the C64?
>>> Could one do say 360K floppies via this hardware for other than the
>>> Commodore?  At least part of the work is done to do more than just
>>> archival like Catweasel, et. al. do, in that it can also write.
>> The X*1541 cables (this would be an xum1541) still talk to the drives at a
>> relatively high level, since the 1541/71/81 family are all intelligent
>> peripherals. So:
>> For the 1541, which is strictly Commodore GCR, no.
>> For the 1571, which can do a variety of MFM formats, maybe, but I'm not
>> aware that OpenCBM supports that. On the other hand, since it's MFM, you
>> could easily just use something else.
>> --
>> ------------------------------------ personal:
>> --
>>    Cameron Kaiser * Floodgap Systems * *
>> ckaiser at
>> -- Diamonds are forever.
>> ------------------------------------------------------

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