How to read recalcitrant floppies?

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Sat Apr 17 16:00:02 1999

On Sat, 17 Apr 1999, Ethan Dicks wrote:
> . . .
> that have read errors that DOS won't get past, bad sectors and the like.

For most situations it surely wouldn't matter. But for diskette repair,
it would actually help to be more specific on the exact error messages.
For example, with a "Parity error", or even "Data error during read", then
it may be possible to easily recover a partially correct sector content.
But NOT with a "sector not found" error, which can only be fixed by
patching up the sector headers.

> Are there any tools to go divining on DOS floppies that work better than
> an endless succession of "R"etries? It's an all or nothing prospect; the
> first disk has the install file, the remaning disks have a chopped monolithic
> data file. If one disk can't be read, the whole set is fundamentally useless.
> Thanks for any suggestions.

The Central Point "Option Board", running the TE (Track Editor) program
can be quite useful for such repairs. It will let you view what it thinks
are the data bits, and/or what it thinks are the clock bits. By fiddling
with them and then writing it back, you may be able to repair the damage,
even damage to the sector headers!
Another similar tool is Trakcess running on a TRS-80 model 3.

Sometimes R-etrying enough times can actually work. If you write a short
routine to read the suspect sector with INT13 in a loop, you might
eventually get a successful read.

--
Fred Cisin                      cisin_at_xenosoft.com
XenoSoft                        http://www.xenosoft.com
2210 Sixth St.                  (510) 644-9366
Berkeley, CA 94710-2219
Received on Sat Apr 17 1999 - 16:00:02 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:31:43 BST