If you are playing with harddrive controllers, I have a good trick for you to try.

This depends of the mass of the drive you are working with. If they are old large drives, you can program a sequence to do the following:

.For x=1 to MaxCyl {
. . seek cyl(0)
. . seek cyl(x)
. . x++
.}

Since you're talking about an old chip, the drive may be 5 or 10 years old in which case, you might get a "desk shaker" when the seek test reaches a harmonic frequency with the desk.

20 years ago I designed hard drive controllers for Multibus and I've probably told this story before but what we'd do in the lab when we had new engineer or guest is to program a dynamic seek test and slowly excuse ourselves from the lab leaving the target alone for a few minutes. In about three to four minutes, the seek test would reach the harmonic region and for about 30 seconds shake the lab table quite violently and then progress beyond harmonic range and quiet down.

Obviously the poor guest alone in the lab would come running for help and all would be quiet by the time we got there.

Varients of the game would explain the shaking phenomenon as either our Texas Earthquakes or as some rumored haunting by the previous building owner. Its amazing what people are willing to believe. :)

-Jay C. Box