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From: david@wiley.UUCP (David Hull)
Newsgroups: comp.sys.mac
Subject: Re: MAC 256K SIMMs --> Mac ][  HELP
Message-ID: <1562@wiley.UUCP>
Date: Fri, 13-Nov-87 01:28:55 EST
Article-I.D.: wiley.1562
Posted: Fri Nov 13 01:28:55 1987
Date-Received: Sun, 15-Nov-87 03:18:48 EST
References: <5134@cisunx.UUCP> <259@dbase.UUCP> <11540041@hpsmtc1.HP.COM>
Organization: TRW Inc., Redondo Beach, CA
Lines: 23

In article <5134@cisunx.UUCP> jasst3@cisunx.UUCP (Jeffrey A. Sullivan) writes:
>Also, is it possible to un-do a 2M expansion to an SE so I could use the 2
>1M SIMMs in the ][ and put the 256K SIMMs back in the SE?

To expand the memory in an SE to more than the original 1 megabyte, you
have to cut a resistor out (my guess is that this resistor sets the
starting address of the second bank of memory).  If you cut through
only one of the leads to the resistor, you might be able to undo the
upgrade if you blobbed some solder on the cut, but it would be ugly.

The resistor is near SIMM #1, and is labeled "256K."  The 1M SIMMS go
in the slots labeled "SIMM 1" and "SIMM 2."

You should use 120ns SIMMS in your Mac II.  Chip tolerances being what
they are, you can probably get away with 150ns SIMMS, but I wouldn't
recommend it.  The Mac SE will use either kind with no problem.
I think that most upgrades sold today are 120ns SIMMS, though.  The
Apple upgrade is.  Check before ordering.

-David
					---------------------------------------
					David Hull  TRW Inc.  Redondo Beach, CA
					  ...!{uunet,cit-vax,trwrb}!wiley!david