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Path: utzoo!linus!decvax!ittatc!dcdwest!sdcsvax!carl
From: carl@sdcsvax.UUCP (Carl Lowenstein)
Newsgroups: net.arch
Subject: Re: Timing sensitive devices
Message-ID: <1468@sdcsvax.UUCP>
Date: Mon, 24-Feb-86 17:33:21 EST
Article-I.D.: sdcsvax.1468
Posted: Mon Feb 24 17:33:21 1986
Date-Received: Wed, 26-Feb-86 21:09:37 EST
References: <1475@seismo.CSS.GOV>
Reply-To: carl@sdcsvax.UUCP (Carl Lowenstein)
Organization: EECS Dept. U.C. San Diego
Lines: 13

In article <1475@seismo.CSS.GOV> mo@seismo.CSS.GOV (Mike O'Dell) writes:
>Sorry to break the news, folks, but almost every Unibus device
>ever attached to a PDP-11 or a VAX has timing sensitivites which
>must be considered when stroking the hardware from fast machines.
>(The 780 Unibus adaptor itself is certainly in this group!!)

Putting on my hardware hat for a moment, I would like to assert that
1) the 780 Unibus adaptor is not a particularly fast machine, and
	has its own problems
2) there are interlocked timing handshakes on the Unibus which make devices
work.  Every device that I have seen that was designed with the bus spec.
in mind has worked over a wide range of bus speeds, some devices that tried
to cheat on the timing have not worked.