[Coco] Re: Bellingham User Group Stuff

[Gene Heskett]

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.
>>>
>>> Boisy
>>
>> 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"
> floppies.

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.

-- 
Cheers, Gene
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Copyright 2004 by Maurice Eugene Heskett, all rights reserved.