Xref: utzoo comp.sys.mac:44252 comp.sys.mac.hardware:844
Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uwm.edu!marque!studsys!stevej
From: stevej@studsys.mu.edu (jovanovic)
Newsgroups: comp.sys.mac,comp.sys.mac.hardware
Subject: Mac II upgrade
Keywords: Mac II, PMMU, 68030, 68882
Message-ID: <722@studsys.mu.edu>
Date: 14 Dec 89 22:42:50 GMT
Followup-To: poster\
Organization: Marquette University - Milwaukee, Wisconsin
Lines: 23

I have a Mac II that I'd like to upgrade, but I'm not sure about what
the best way to do this is.  I know the 68881 and 68882 are pin
compatible, so replacing the 68881 with a 16MHz 68882 is no problem.
But what about using a 25MHz 68882?  Or would this show no real
performance increase because of hardware-imposed wait states?

Also, I'd like to add a PMMU, but would rather replace the 68020
directly with a 68030, although I don't know whether or not they're
pin compatible.  If they're not pin compatible, then I guess that
means I have to go with a PMMU.  But if by chance the 68030 is pin
compatible, again, what real effect would there be in using a 
25MHz chip rather than a 16MHz chip?  Are wait states software-
rather than hardware- imposed?

Thanks for your help, and I'll summarize replies in a future posting.

			-steve.

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stevej@studsys.mu.edu
Marquette University
Electrical Engineering