[Coco] Re: Bellingham User Group Stuff
gene.heskett at verizon.net
Tue Feb 3 23:31:40 EST 2004
On Tuesday 03 February 2004 23:21, Theodore Evans wrote:
>On Feb 3, 2004, at 5:26 PM, Gene Heskett wrote:
>> On Tuesday 03 February 2004 17:57, Boisy Pitre wrote:
>>> I suspect that bit 1 of byte $10 in LSN0 is not set. It should
>>> be, indicating to the driver that the disk is formatted as a
>>> 96tpi disk.
>>> Look at offset $10 of LSN0 of the disk image. It should be $03,
>>> not $02.
>> That would depend on whether he wrote them to a 5.25", or to a
>> 3.5" diskette. The 3.5 was 135 tpi from the gitgo, so that bit
>> should not be set for a 3.5" formatted disk as there is never a
>> chance of a tpi miss-match there.
>I have seen 40 track 3.5" floppy drives. They are exceedingly rare.
>No consensus has ever been reached as to whether to set or clear the
>"96 tpi" bit for 3.5" drives. No doubt there are a significant
> number of people who merely used the 720k 5.25" descriptor for
> their 3.5" floppy drives. Basically if their descriptor has this
> bit set it should be set and if not it should be cleared.
> Unfortunately this has caused some conflict when exchanging 3.5"
yes, it has even here at the Heskett Ranchette, so I've been rather
resigned for the last few years to editing that byte, and the byte at
$3F in lsn0 too, to correct that. But before I do, I make sure I
can't read it in a 48tpi drive if its a 5.25" disk. Since track 0 is
often readable, I double check it by doing a dir -e, so the drive is
forced to seek to other tracks and it that errors, its probably a
real 96 tpi disk.
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Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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