Hi! (I sent this e-mail this morning but seems like it haven't made it to the list due to a problem at mail.videoton.hu). William Levak wrote: > > On Mon, 26 Nov 2001, [iso-8859-1] Hársfalvi Levente wrote: > > > 8x50 ---> IBM 1.2M: mechanically incompatible (100tpi vs. 96tpi), and > > logically incompatible (GCR vs. MFM, like above). Even if the PC could > > read the non-MFM data stream (like with the Catweasel), the misalignment > > would be a hard problem to solve. > > 8x50 drives are quad density and IBM 1.2M drives are high density. They > are nominally the same data density, but the magnetic films are different. > The heads require different magnetic field strengths to read and write. AFAIK SD, DD and QD are about the same in their magnetic parameters. 1.2M drives are surely capable of switching between "low" and "high" density operating mode (that's why they can still record 360K DD disks). With pulling the 'LD line low, the floppy controller can tell the drive to switch to "low density" mode. (I experimented with this setting and found that it's even significant during reading a disk. By setting the PC drive onto a halftrack of a Commodore disk, I got a lot more false spikes on 'RD when the drive was set to HD mode ( when 'LD was not asserted)). So from this side, I guess there would be no problems with either reading or writing a 8x50 or SFD1001 disk in a PC 1.2M drive ...if there were no differences in the track alignment. But there are. Best regards, L. Message was sent through the cbm-hackers mailing list
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