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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: comp.arch,comp.sys.m68k
Subject: Re: 68020 speeds and wait states
Message-ID: <8009@utzoo.UUCP>
Date: Sat, 9-May-87 22:32:18 EDT
Article-I.D.: utzoo.8009
Posted: Sat May  9 22:32:18 1987
Date-Received: Sat, 9-May-87 22:32:18 EDT
References: <5635@shemp.UCLA.EDU> <1774@im4u.UUCP>, <814@killer.UUCP> <8003@utzoo.UUCP>, <2106@hoptoad.uucp>
Organization: U of Toronto Zoology
Lines: 21

> Actually, Sun-2's all ran at 10MHz with no wait states...

Wups, my mistake, John is right (as he should be, since he was at Sun when
all this was happening...).  Bit rot in my memory; I did know better.

> Early Sun-3's actually run 16.67MHz (60ns clock) at 1.5 wait states.

It gets so annoying adding the extra digits that I tend to abbreviate 16.67
to 16...

> ... it could probably have been done at 1 wait
> state (indeed, ISI did it that way) but after years of design-on-the-edge,
> there was some sentiment for making the Sun-3's easier to manufacture.

ISI in fact does 1 wait state on reads and 0 on writes, presumably by
buffering writes.  Interesting machine; we almost bought one.  Definitely
faster than the 16.67-MHz Sun-3s by a modest margin, but other factors
weighed in and we went with a Sun.
-- 
"If you want PL/I, you know       Henry Spencer @ U of Toronto Zoology
where to find it." -- DMR         {allegra,ihnp4,decvax,pyramid}!utzoo!henry