Wiedemann@RADC-MULTICS.ARPA (08/08/84)
We have a vintage Imsai 8085 S-100 system with two 8" SS/SD drives
here that we are configuring as an RCPM system for out local clup.
(Mohwk Valley Microcomputer Club) All the software is finished and runs
well. I purchased and installed the Optronics Technology timeout board
on the disk drives to reduce disk/head wear,since this board will be
operational 24 hours a day.
Here's the problem: The timeout board triggers on the "drive
select" line from the controller. When it sees this signal, it turns
the 115VAC back on to the spindle motor. Several seconds after the loss
of this signal, the board will power the spindle motor down. This
system uses "Fischer-Freitas" CP/M 2.2. I need to find someone who has
worked with this BDOS and can point me in the direction of how to patch
it to bring the drive select down after a disk read. I'd do it myself,
but time is at a premium right now and I'd like to get this board on
line.
Thanx much, in advance!
Wolf Wiedemann RADC-MULTICSmlsmith@nadc.ARPA (08/08/84)
I don't know how much applicability this has but here goes:
We had a Digital Group (aka AEON) system up with SS/SD 8" disks running CPM and
Oasis on a time shared basis. The disks would crash on power down intermittently
and the select lines had come high. The answer we got from DG was that they all
do that! We abandoned SD and installed DD disks with a new disk controller.
Result: three years without a controller glitch (one disk regulator failure).
Recommendation: Look at the disk controller before attacking BDOS as our
problem was language independent.
good luck,
mlsmith@nadc.ARPA
P.S. A delay after disk read is normal - if the power on the motor shuts down
immediately after completion some systems declared the previous data
shipped bad and tried again resulting in endless retransmissions. Also
some timeout boards include a longer delay >30 seconds to cover the
random access file case where excessive cycling would occur.