11 Oct
2008
11 Oct
'08
1:17 p.m.
[Disk Change]
with 8" drives with line-powered spindle motors.
We just polled the
write-protect sensor on old 5.25" drives to do the same thing.
The HP9836 system that I've been working on has a pair of 5.25" drives
which are effectively permanently enabled (the 'MX' jumper is fitted) and
thus have spearate cables back to the contoller board. The write-protect
lines trigger flip-flops for a disk change function (as well, of course,
as being used for the write protect function) while the index lines also
trigger retriggerable monostables for a ready function (if index pulses
are happening sufficiently often, there must be a disk in the drive, it
must be turning).
-tony