CompuPro floppy controller differences

Fred Cisin cisin at
Mon Sep 18 18:17:25 CDT 2006

On Mon, 18 Sep 2006, Tony Duell wrote:
> Rememebr the data rate of 8" SD is the same as that of 5.25" DD. I have
> an idea the data separate _will_ lock to 8" SD (which is still 250kbps),
> and you can then program the FDC chip to do single density operations. I
> have never tried this, though.

The IBM 5150 FDC board had NC to the FM (v MFM) pin on the 765,
To program it to do "single density" would require that a little bit of
that "programming" be done with solder.

Many later chips, such as the 37C65 permitted switching between FM and MFM
under software control.

Grumpy Ol' Fred     		cisin at

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