Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site ucbvax.UUCP
Path: utzoo!linus!decvax!tektronix!ucbcad!ucbvax!root
From: root@ucbvax.UUCP
Newsgroups: fa.info-vax
Subject: 730 Unibus speed revisited.
Message-ID: <743@ucbvax.UUCP>
Date: Fri, 9-Sep-83 13:14:50 EDT
Article-I.D.: ucbvax.743
Posted: Fri Sep  9 13:14:50 1983
Date-Received: Sat, 10-Sep-83 08:04:40 EDT
Sender: root@ucbvax.UUCP
Organization: U. C. Berkeley Computer Science
Lines: 21

From GEOFF5@SRI-CSL  Fri Sep  9 10:14:12 1983
I asked several days ago if anyone had ideas why my Versatec printer/
plotter (heavy character IO) runs faster on a 730 than on the 780.

I got 3 responses all suggesting that it is the DMF32 which runs faster
than a DZ11.  I appreciate these responses, however the Versatec does not
run off a serial port, it has its own parallel interface (which can run DMA
or character - senario occurs in character mode).  Thus the DMF32/DZ11
difference does not explain it.

One response also mentioned the 730 Unibus goes 20% faster than the 780's.
Is this true?  I thought the Unibus was clocked at some fixed speed?

Another idea I had is that the Unibus is connected more difectly to the
730 and so maybe there is one less layer of software to go through.
(I think interrupts are directly vectored as in the 750 for example.)

Anyone know what is really going on?

					Rg
-------