🚀 go-pugleaf

In article <BxLH5B.7ox@news.cso.uiuc.edu>, shair@barolo.cso.uiuc.edu (Bob Shair) writes:
> Sorry, but the SCSI support in the RT is only for the IBM differential
> SCSI adapter, used to attach, for example, 9332 and 9335 disk drives.
> These are huge, expensive, external disks (400MB!!!) which needed the
> long cables which the more elaborate differential SCSI permits.
But..
You can run NON-IBM SCSI disks on the IBM SCSI adapter.  As long as
they are either native differential, or run thru a Rancho diff-to-single
converter box.  AIX and VRM will quite happily initialize the drives
ONCE you hack a ddi with the correct device geometry, and insert /etc/system
stanzas by hand.  (The Devices command INSISTS on checking for a 9332
disk on the SCSI controller..   :-(  )

You can't run diagnostics on them, or perform a low-level format, but if
they are already formatted, just zero the first 10 cylinders to all zeros
and VRM will put the minidisk partition table on the "empty" drives!

> Don't know anything more about it; 
> don't think you can attach anything but 40MB disk drives to the adapter
> you now have.  
Sad, but true.. It is a stock AT MFM controller for the R40 drives.. :-(

> Your best bet is to find someone who would let an "EESDI" disc controller
> card and some 114MB or 310MB disk drives go cheaply;  trying to support
> devices not originally supported in AIX is probably NOT the way to go.

Writing your own SCSI card support would be a tough job, true enough..
especially that ornery VRM to get JUST right...
But, might be quite worth it once the EESDI controllers are all gone,
and not just ANY ole ESDI drive will work with the IBM EESDI controller.
SCSI disks are getting cheaper and cheaper and larger every day!
Don't go over 1 Gig, AIX 2.2.1 and VRM just WRAP the block number
back to ZERO!

Later,
markw
-- 
M. Whetzel 
Home: markw@antimatr.hou.tx.us        | IBM RT/125 running AIX 2.2.1 
UUCP ..!uhnix1!lobster!antimatr!markw