Reading an MFM hard drive with a floppy disc analyser

Jim Battle frustum at
Fri Dec 5 18:03:45 CST 2008

Philip Pemberton wrote:
> The read clock on a CW is about 8MHz or so, if memory serves. 
> Effectively that's ~16 clocks per bit cell time (at 500kbps MFM that 
> is). The hardware I'm building up is going to sample at 20 or 40MHz 
> (software selectable), which is 40 (or 80) clocks per bitcell on 500k 
> MFM, or 4 (or 8) on 5Mbps MFM...

Quoting the catweasel manual:

To set the clockspeed with the CatOption register, reset the memory counter
to 0 by writing 0 to the CatAbort register. Writing 0 to CatOption will set
the clock rate to 14Mhz. Writing 128 (0x80) to CatOption will set the clock
rate to 28Mhz, and writing 192 (0xc0) to CatOption will set the clock speed
to 56Mhz (to be precise, 56.644Mhz).

> But it'll take a bloody age transferring that much data over USB2 Full 
> Speed (1.2Mbps peak).


USB1 was 12 Mbps peak.  USB2 is 480 Mbps peak.


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