[sebhc] Diskette Drives

Dave Dunfield dave06a at dunfield.com
Sat Jun 17 21:32:01 CDT 2006

> Does anyone know about diskette head alignment?
> I got some Tandon TM100 drives off EBAY. They are single sided and look 
> like they should work, but diskettes written on the normal H17 won't 
> read on the Tandon. Is there some different head alignment or something?

> The drives may be out of alignment, but the correct alignment for all 5.25"
> drives is the same.  You can [theoretically] check it with a digital
> diagnostic disk, but to set it, you need an analog alignment disk and an
> oscilloscope.

Agreed that to do it correctly you need an alignment disk and a scope,
however If you have a "known good formatted disk" (ie: one formatted
in the drive you most want to be compatible with :-) you can do a
passable job of aligning the drive using ImageDisk's Align/Test function.
NOTE: To do this, you would need to install the drive in a PC running
DOS or Win9X.

I've  just added a section to the manual with a bit more information on
doing this - not posted yet, but I can send it to you if you want it (should
have it posted sometime next week).

TM100's should be standard tracks - if they are single sided, they are
most likely 48tpi 40 track drives - there are 96 and 100 tpi TM-100's,
however I believe these were all double-sided.

Most TM-100 have the drive model inside the door release lever -
look up at the front of the lever from below when it is in the raised
position. A 48TPI drive should read "TM-100-2", at least for the
double sided version - I think my single-sided TM-100's are still
called -2's but I haven't checked.


dave06a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
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