Open-source floppy reader: the data separator/sync-er works!

Christian Corti cc at
Fri Apr 13 04:01:44 CDT 2007

On Thu, 12 Apr 2007, dwight elvey wrote:
> In FM there is always a clock bit and a location for the data bit. Missing
> clock is just that, missing clock! No change to the data bits.
> MFM may or may not have a clock, depending on the data 1 bit density.
> If missing a clock, it means where a clock bit should be related to data.

I know what clock bits are ;-)
The question was, why three missing clock bits (the MFM address mark has 
only one missing bit at position 5). But I've found out that this applies 
to the FM address mark where the clock bits 2, 3 and 4 are missing. The 
IBM manual just wasn't precise enough on this point.


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