Software-based floppy disc data separator

Chuck Guzis cclist at
Wed Jun 16 22:00:20 CDT 2010

Sigh.  There are times when I'd be happy to get one disk an hour.

Finally solved (I think) the mystery of the "slipping belt".  It's 
not that.  The data of every sector on the track looks to be correct, 
but all of the *data* CRCs are foobar.  The CRC for the IDAMs is 
fine.  Screwball firmware?   Just a couple of tracks like this, but 
they all have goofy data CRCs on every sector.  The histograms of the 
read pulses from those sectors shows no aberrations--3 nice clean 
peaks, about where you'd expect them.

Not an LSI controller of any sort, BTW.

In the middle of all of these things is a 32-hard-sector FM-encoded 
floppy.  I've got to figure out what the customer wants to do with 

Most people don't realize how many formats there are once you get 
outside of the "Personal Computer" arena.  These are from a Fairchild 
wafter tester.

On to a batch of 240K Brother WP floppies (3.5" GCR).


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