Path: utzoo!utgpu!watmath!clyde!att!rutgers!mailrus!eecae!cps3xx!rang
From: rang@cpsin3.cps.msu.edu (Anton Rang)
Newsgroups: comp.sys.mac
Subject: Re: Mac II processor upgrades
Message-ID: <1248@cps3xx.UUCP>
Date: 6 Dec 88 21:09:56 GMT
References: <65023@ti-csl.CSNET> <3356@ucdavis.ucdavis.edu>
Sender: usenet@cps3xx.UUCP
Reply-To: rang@cpswh.cps.msu.edu (Anton Rang)
Organization: Michigan State University, Computer Science Dept.
Lines: 34
In-reply-to: ecs175f037@deneb.ucdavis.edu's message of 6 Dec 88 16:59:19 GMT

In article <3356@ucdavis.ucdavis.edu>, Greg DeMichillie
  (lgdemichilie@deneb.ucdavis.edu) writes:
>In article <65023@ti-csl.CSNET> holland@mips.csc.ti.com (Fred Hollander) writes:
>>I heard that there is a 68030 replacement for the Mac II that runs at 33MHz
>>for about $1000.  First of all, how can the processor run faster than the
>>rest of the motherboard?

>The processor would have to have several wait states for each Nu-Bus access
>since the bus is only clocked at 10MHz :-(

  The 68030 replacement must be on a separate board, I would guess.
If it has a reasonably large cache (say, even 8-16K) there wouldn't be
too many NuBus accesses (hopefully).  There would indeed be several
wait states for NuBus access, but this wouldn't occur that often.

>So, some operations will certainly be much faster with the upgrade, don't
>expect everything to suddenly be twice as fast until Apple upgrade the Nu-Bus
>to operate at higher clock speeds (a la Steve Jobs' NeXT)

  Of course, the NuBus standard is 10MHz; so no standard NuBus cards
would work with one running at a higher clock speed.  The cache ought
to give pretty good performance (remember, there are lots of large
computers with slow memory).
  A graphics coprocessor (to reduce the amount of cycles spent waiting
for video memory updates) would help a lot, too.  Anyone for designing
a custom QuickDraw chip?  (Or a microcoded Display PostScript
interpreter, even? :-)

	Anton

+---------------------------+------------------------+----------------------+
| Anton Rang (grad student) | "VMS Forever!"         | "Do worry...be SAD!" |
| Michigan State University | rang@cpswh.cps.msu.edu |                      |
+---------------------------+------------------------+----------------------+