From: utzoo!decvax!ucbvax!info-vax
Newsgroups: fa.info-vax
Title: Re:  FPS AP-120B Array Processor
Article-I.D.: ucbvax.316
Posted: Fri Dec 10 02:45:50 1982
Received: Sun Dec 12 13:39:54 1982

>From ron@BRL  Fri Dec 10 02:40:40 1982
Mail-From: ARPANET host BRL-BMD rcvd at 9-Dec-82 0924-PST
To: ABOORNAZIAN@Bbng
Cc: info-vax@Sri-Csl, aboornazian@Bbng, depesa@Bbnf, lanoue@Bbnf, dipace@Bbnf
Remailed-Date:  9 Dec 1982 2209-PST
Remailed-From: the tty of Geoffrey S. Goodfellow  <Geoff5 at SRI-CSL>
Remailed-To: Info-VAX@SRI-CSL: ;

We have an FPS AP120B which worked fine by itself on our 11/70 but
died miserably in a multiuser situation when other peripherals were
in use.  The symptoms were Unibus hangs and interference with other
devices.  We got no help from FPS (nick named Fly-By-Night Convolvers).
After talking to the guys at Stanford who wrote the UNIX software
for the thing, we discovered there was a design error in the UNIBUS
interface board (which FPS knew about but refused to give us an ECO
without us paying $900).  The problem is that the interface in the
interupt procedure places the vector on the address lines and then
before waiting the specified deskewing time, they send the INTR signal.
All kinds of hell break loose on the bus.  The fix was to run the INTR
signal through a couple of spare inverters on the side of the board.
Another problem is that we were never able to get the board to work
with the throttle count set above 1 or 2.  (The installer had set it
to 16 or something like that).  This is a little rotory switch at the
top of the UNIBUS interface board in the AP cabinet.

Hope this helps.

-Ron