formatting and checking floppy disks for bad sectors

[Maciej W. Rozycki]

On Sat, 30 Jul 2016, Fred Cisin wrote:

> > I have a heap of floppy disks on hand. Most with old junk on them. Some are
> > going bad, and have bad spots in the middle of the disk. Is there a good
> > utility for either windows or dos that can format a floppy and mark the bad
> > parts of the floppy to not be used?
> > If anything, such a utility can let me find what disks are having issues
> > and i can pitch them before i run into the aggravation of finding there is
> > an issue with a disk down the line.
> 
> FORMAT on any old version of DOS.  It formats and verifies (confirms
> readability), and on conclusion reports amount of space locked out.

 There used to be a `fdformat' utility available providing fancy stuff for 
DOS users like sector physical and logical shifting, interleaving, unusual 
geometries, etc.

 You could use physical shifting (track lead and inter-sector gap 
rearrangement) to avoid bad spots in some cases altogether, and logical 
shifting (out of order sector ID assignment) to improve data transfer 
performance -- typically ~twice compared to results obtained with the 
regular `format' utility shipped with DOS.  Some other features were 
available I don't remember offhand anymore; basically you had much control 
over the NEC µPD765 FDC chip itself with this tool's command line options.

 Back in 1990s the software package used to be carried by the usual FTP 
sites with DOS software, so I guess it still has to be available online 
somewhere.  I highly recommend it if you're still into the floppy business 
and don't use Linux.  The plain `format' command supplied with DOS gives 
you little control really and produces poor performance floppies.

 HTH,

  Maciej