This is the schematic diagram of the Commodore 1541/II floppy drive. I drew
it 'coz I couldn't find it in anywhere. It was drawn with CirCad, on a
PC/AT, but I made a GIF file to make it reproducable without any vector-like
By the way, some things were not fully recognised. The Sony chip is an ASIC,
I suppose to get more information about it from Commodore; or simply, compare
the diag with an older 1541 release's one. The other new chip (...I don't
remember it now) contains some more features than the older custom-chip; It
seems to contain the whole clock-divisor part, which was done with a 74LS193
in older versions. ...This way, I see very hard to modify the unit to read MFM
disks, for example :-(
I don't think if it's free of some funny bugs, so please, send comments/
feedbacks about this one if You think it so.
Enjoy... ...Well, I hope, at least You'll not have to trace the board, when
trying to make getting up a dead drive, as I did... 8-|

Harsfalvi Levente


Some patches. I found a bug in the schematic diag, there was a lose connect
between the custom chip's MTR pin (13) and the uPa2003's 6. pin. So this is a
fixed version. '97.01.08