HP LIF floppy disks and bad sectors - test-drb@ccmp.vtda.org

29 Jan 2013


On Tue, 29 Jan 2013, Fred wrote:> On Tue, 29 Jan 2013, John S wrote:>> To
conclude, information such as the IDAM content won't be readable by a
...
 > PC with a normal FDC, so this approach looks
limited. I am in touch with
> Ansgar reading his wonderful hpdir project, which I am using with my
> Series 80 disks on an 82901M drive, so will point him here for a bit
> more light reading ;-) 
...
  <Oversimplified>
 PC WILL sense the IDAM.
 In "normal" read/write, the PC works the same.  It steps to the track,
 finds a sector header, checks it, and if it is the one requested,
 reads/writes. Many thanks Fred for correcting me and for the mini-tutorial.
...
  The NEC chips even have a [little used] command to
read sector header! OK, I'm sure there would be some mileage in tools that could
use this feature. I guess not all PC FDC chips would have this capability though. (FWIW I
am a fan of the Adaptec 1542 cards with their built in FDC, two types depending on model
but both OK with FM disks).
Coming back to LIF disks with bad tracks, as I wrote above I am a fan of HPdir, and am
using a PC with an HPIB controller and 82901M floppy drive, so avoiding any use of the
PC's FDC.
I've got a further query on the 82901M and 9121 drive which I'll raise in a new
thread. Regards,John