Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!bsu-cs!mithomas
From: mithomas@bsu-cs.UUCP (Michael Thomas Niehaus)
Newsgroups: comp.sys.mac
Subject: Re: Another Mac SE/30 question
Keywords: SIMM
Message-ID: <5562@bsu-cs.UUCP>
Date: 4 Feb 89 20:10:19 GMT
References: <6671@paris.ics.uci.edu>
Distribution: usa
Organization: CS Dept, Ball St U, Muncie, Indiana
Lines: 58

In article <6671@paris.ics.uci.edu>, poleary@bonnie.ics.uci.edu (Petey O'Leary) writes:
> I currently use a Mac SE with 1 meg of memory and am in desperate need of
> more memory (the LSC 3.0 debugger doesn't run on my whimpy 1 meg machine).
> I would hustle out and get a 1 meg SIMM but this SE/30 business has me
> worried:  if and when I upgrade my old SE to the new SE/30, will I have
> to throw out my SIMM?  I don't have the tech specs for the SE/30, so I
> can't just look it up.  I assume that the SE/30 will take the same SIMM's
> that the SE does, but you can never be too sure about these things...
> 
> Peter O'Leary.
> "I still believe in God, but God no longer believes in me" - Wayne Hussey

Hustle out and get a 1 meg SIMM?  You will need to get at least 2 meg.  The
SE/30 takes the same 120 ns memory that Apple has been using in the SE for
some time.

It seems to me that many people have questions about memory, so I will attempt
to give a general overview of all of the machines:

1.  Mac Plus.  The Mac Plus requires 150 ns SIMMs or better.  These chips must
    be installed in sets of 2.  There are 4 SIMM slots available, so the
    possible memory configurations are: 1M,2M,2.5M, and 4M.  The installation
    of more memory in a 1M machine will require the removal of two of the
    four 256k SIMMs to make room for two 1M SIMMs.  Do NOT buy a 1M expansion
    kit, because odds are it will be 4 256k chips, which will not do you any
    good.  Because some resistors and/or jumpers must be changed, it is not
    recommended that you try this unless you are absolutely sure of what you
    are doing.

2.  Mac SE.  The Mac SE is very similar to the Mac Plus, except that (for the
    most part) the SE ships with 120ns SIMMs.  The machine in its standard
    1M configuration has 4 256k SIMMs in it, filling all four of the available
    SIMM slots.  The upgrade process is the same as the Mac Plus.  All of the
    same configurations are possible, and the same warnings apply.

3.  Mac II, Mac IIx, Mac SE/30.  All three of these machines have 8 SIMM slots.
    The SIMMs for these machines must be 120ns or faster.  Because of the 32 bit
    logic of these machines, the SIMMs must be installed in sets of 4.  This
    makes these configurations possible: 1MB (4x256k), 2MB (8x256k),
    4MB (4x1M), 5MB (4x256k and 4x1M), and 8MB (8x1MB).  I would not recommend
    ever going to a 2MB configuration, because you must then discard some of
    the 256k SIMMs to put in the higher density 1MB SIMMs.  Installation of
    these chips is much more straight forward, but because of static concerns,
    should be installed by an authorized dealer.

In the future, if Apple introduces a faster machine, it will probably require
faster memory.  I believe that to introduce a 25MHz machine, 80ns memory must
be used (unless you want to add wait states).  With the memory situation as it
is now, the supply of these chips would be very short, causing the price of
such a machine to be more than most people would even consider.  When memory
prices come down and supply improves, expect to see a faster machine.  (I see
this as the reason that the IIx is "only" a 16MHz machine.)

Michael Niehaus
Apple Student Rep
Ball State Unversity
UUCP: ..!{pur-ee,iuvax}!bsu-cs!mithomas
AppleLink: ST0374