4 Feb
2006
4 Feb
'06
11:18 p.m.
Roy J. Tellason wrote:
On Saturday 04 February 2006 05:32 pm, Chuck Guzis
wrote:
I'm sure I've mentioned before about the 1541 test and alignment disk we
used to have in a workshop I used to work at...
Basically it had tracks written starting too far out and progressively
moving in until they were too far in. They were, I believe, written
with "worst case" patterns, and possibly a bit "quiet". The first few
tracks on the disk were written fairly hot so that even if the head was
a bit out, it would still boot.
What would then happen was it would step through the disk a couple of
times, working out how "close" the head was by determining which track
gave the least CRC errors.
Then it would work out which way the head needed to be moved, wind it
back and then smack it off the opposite end stop a few times. Then it
would cycle through its calibration reading again, and repeat until it
was done.
Brutal, but it worked surprisingly well.
Gordon.
...and I've got a couple of 5.25"
floppies where seeking to anything past
about cylinder 84/42 (depending on the drive) will cause the head to jam,
requiring manual intervention to free it.
I used to see this fairly often when I was fixing commodore stuff, the head
on the 1541 would get jammed to the inside, and one would have to open the
case and manually move it out before the drive would work again.