Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ukma!rutgers!cmcl2!ccnysci!alexis
From: alexis@ccnysci.UUCP (Alexis Rosen)
Newsgroups: comp.sys.mac
Subject: Re: Mac memory speed confusion
Keywords: Memory speed, Cache memory, Wait states, Virtual Memory, Help
Message-ID: <1572@ccnysci.UUCP>
Date: 13 Apr 89 08:58:25 GMT
References: <7400@spool.cs.wisc.edu>
Reply-To: alexis@ccnysci.UUCP (Alexis Rosen)
Organization: City College of New York
Lines: 27


Yup, there sure is a lot of confusion...

Whoever said the Mac II runs no waits? I _wish_ it did. Apple was inexcusable
cheap and lazy not to put a cache in. Not putting it in the IIcx, IIx, and
SE/30 is just sickening. Precisely because that $300 cache board (which would
cost Apple all of maybe $40 to manufacture on the motherboard) really does
make a 20-30% speed difference.

The Mac II runs 2 wait states, regardless of which MMU you use (the bogus
Apple one, or the 851). Most people think the IIx gets its speedup from the
added data cache, but in fact it comes mostly from the fact that with the
integrated MMU, it runs at only one wait state. The same goes for the SE/30
and the Mac IIcx.

I have the cache board. It's an excellent product which does exactly what
it is supposed to do. If you have a II, you should buy one. It generally
makes your Mac II equall to the IIx in speed, maybe a hair faster on some
things.

(BTW, I am certain about the II. My information about the '030 machines
comes from a variety of sources including two apple engineers, and I have
yet to see them proved wrong.)

---
Alexis Rosen
alexis@ccnysci.{uucp,bitnet}