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Date: Mon, 15 Sep 1997 16:52:09 +0930
From: Greg Lehey <grog@lemis.com>
To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>
Cc: hackers@FreeBSD.ORG
Subject: Re: Do *you* have problems with floppies?
References: <19970914142654.GG28248@uriah.heep.sax.de> <199709142144.OAA22143@usr09.primenet.com> <19970915082959.QR50985@uriah.heep.sax.de>
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In-Reply-To: <19970915082959.QR50985@uriah.heep.sax.de>; from J Wunsch on Mon, Sep 15, 1997 at 08:29:59AM +0200
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On Mon, Sep 15, 1997 at 08:29:59AM +0200, J Wunsch wrote:
> As Terry Lambert wrote:
>
>> Actually... 0x42 READ TRACK does not check the sector number stored in
>> the ID field.  This could be a curse as well as a blessing; I don't
>> know how it could deal with interleaved data.
>
> You apparently don't know much about this command at all. :-)  Trust
> me, i've been using it once (in CP/M), it's only useful as a debugging
> tool, nothing else.

I'm not too sure we're talking about the same command.  It's been a
while, but my recollection of READ TRACK was that it did just that: it
started at the index pulse and returned everything that it could sync
on until it got another index pulse, including gaps, flags, headers
and all.

I once used it for reading a floppy which had been written on a
strange disk controller.  All the gaps were filled with 1 bits instead
of 0s (I can't remember exactly, it's been 18 years, but I seem to
recall that the 1793 needed at least 6 bytes of 0 bits before a flag
in order to be able to recognize it).  It worked surprisingly well.

Greg