OK, I'll fess up.  It was me who made the (with accurate
subject line) comment about third-party discs (IODEVACC on
5.0 contains references to DEC single-ended and fast-wide
SCSI drives), and then said I couldn't make use of them
because I had to move backwards from 5.0 to 4.0.
 
The reason was 'long-in-the-tooth' financial applications
(general ledger, accounts payable, purchasing, inventory,
cataloging, cash and asset management).  The original vendor
of the applications dropped off the twig several years ago,
and the successors chose to redevelop in a 4GL that didn't
suit our essentially Powerhouse environment.  We bought contract
maintenance from one of the original developers who had moved
out on his own, and could work with our 'perpetual right to
use' including source from escrow.  Alas, there had always
been some PM code in the applications, never supported and
now apparently unworkable (WHOM intrinisc or procedure to
determine logon id and set internal variables for calling
appropriate screens).  Sounds messy to me, and I think that
under MPE/iX one could find several ways of retrieving this
information without resorting to PM.  Remember, the original
applications were written for MPE/V in Basic then gradually
shifted to COBOL.
 
Anyway, it is not an experience I would wish on anyone, but
have to say that the roll back was technically unconfusing,
just took a LOT of time.  (We run 17 gig.)
 
Problems that arose, all of which were rapidly solved, include
a mysterious lock on one of the MPEX help files which prevented
it being rebuilt and resynched with COMMAND.PUB.SYS (had to
use fscheck to purge it); all IMAGE/SQL dbes and atcinfos
had to have external references resynched; after the install/reload,
the network wouldn't come up until the system was rebooted once
again.  Not all that much considering what a massive floor-sweeping
excercise it was.
 
Two 20-hour days with a brief rest in between left me rather
bruised and fragile.
 
At least now I know my upgrade to 5.0, whenever it comes, will
be a pretty smooth one.
 
Ron
Royal Children's Hospital
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