From: "John S" <john_a_s2004 at
hotmail.com>
Hi,
I have a Transam Tuscan system and recently received a set of boot disks
for it. I am trying to back these up to a PC, but when reading the disks
with Anadisk or Imagedisk I get 'no data' errors on tracks 3 and higher.
The errors get worse from tracks 3 to 15 then nothing can be read. I have
taken the 5.25" drive out of the Tuscan and put it in the PC, and the
contoller passes the TESTFDC tests for single density and double density.
The odd thing about these floppies is that Anadisk reports them as 512 byte
/ sector and 10 sectors per track. The norm for '360K' floppies is 9
sectors / track. The outer sector (track 0) can be read fine with Anadisk,
and I can read the CP/M welcome message.
I was hoping someone could advise on what tricks or techniques I could use?
Would it help for example to slow the drive down below 300rpm?
I assume that with 9 sectors / track there is more time for the FDC to
recgnise the start of each track. I think the Tuscan FDC uses a WD1771
controller, is that better than the NEC765 type-controller and able to pack
more data in? I read on
http://www.s100-manuals.com/Disk-drives.htm that
Kaypro also uses 10 sectors of 512 bytes.
Another thought is to try different PCs, perhaps formating, writing and
reading 10 x 512 byte sectors is another test that could be added to
Dave's TESTFDC program to help find a suitable machine :-)
Lastly (before anyone asks) yes the floppies are soft sectored.
Hi John
It sounds like the disk has tracking errors. Either the drive
you are using is not stepping correctly or the drive it was
written on was not stepping correctly.
Things to check in general:
Make sure there is no old grease on the guide rails for the
head mech.
If belt driven, make sure the surfaces of the pullies are smooth
and clean.
Make sure the head(s) are clean. If a single head, make sure
the pad is clean and flat.
Make sure that the disk turns smoothly when in the drive
and that if belt driven, the belt isn't slipping.
Dwight
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