WD1793 read-track weirdness

From: Patrick <patrick_at_VintageComputerMarketplace.com>
Date: Fri Mar 26 11:48:51 2004

> On Thu, 25 Mar 2004, Bill Yakowenko wrote:
> > Has anybody out there written drivers for the WD1793 floppy
> > disk controller chip? I've been doing that for fun, and have
> > hit on a very strange problem with the 'read track' command.
> > It seems to work just fine, returning a stream of bytes that
> > includes the data for each sector, until it finds a byte with
> > a value of $29 (or 29H, if you prefer). From that point up
> > to the next address mark, it gets garbled data. No other data
> > value seems to have any odd effect. 'Read sector' returns
> > the right data with no weirdness.
> Are you sure it's not a matter of a bad sector on the disk?
> --
> Sellam Ismail Vintage
> Computer Festival

Bill, Sellam's point would be my first guess as well. Are you checking the
status register after the read to see if any errors were flagged during the
operation? You didn't explicitly say that the event happens on ANY track or
sector containing a $29... are you seeing this behavior on one sector, or
all over the disk? --Patrick
Received on Fri Mar 26 2004 - 11:48:51 GMT

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