Question on disc drive encoder

From: Jay West <>
Date: Wed Apr 12 20:02:13 2000

I'm having a problem with my 7900 I'm trying to get up and running that I
wanted to bounce off the folks here.

When you hit the load switch, after spinup the heads seek cylinder 0 and
rest there (and an interrupt is sent to the cpu). However, any command sent
to the drive via diagnostics causes the heads to slowly step out one
cylinder at a time to the innermost track. Then the cpu gets a "no command
flag" message which basically means the cpu never got acknowledgement back
from the drive that the previous operation completed.

This makes me suspect the encoder mechanism. The drive uses an IR
emitter/detector through a glass reticule with sector markings on it. But if
the encoder was shot, wouldn't that make it hard for the drive to initially
seek cylinder 0 upon loading as it does correctly?

Just curious... more of a philosophical question than a need for

Thanks in advance!

Jay West
Received on Wed Apr 12 2000 - 20:02:13 BST

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