eto@spacely.Jpl.Nasa.Gov (Edward Olsen) (02/14/89)
I have been running my Mac Plus with 2.5 MB of memory for a year with a Dove
low profile memory upgrade. I recently received my Apple low profile 2 MB
memory expansion kit (ordered last May), and proceeded happily to move to
4 MB. I want to share the experience, for I have encountered some problems
which I do not understand.
I have three sets of chips:
1) the original 256K ram, which is comprised of -15 chips
2) my first 2MB upgrade, which is comprised of Dove low profile -12 chips
3) my second 2MB upgrade, which is comprised of Apple low profile -10 chips
My Mac Plus is one of the last beige colored ones built, and its ROM
is 128K rev .2 (the so-called Lonely Heifer version). This is apparently the
same ROM version which does not allow you to boot up with a powered-off SCSI
device connected.
I am running System release 6.0.2, and since my boot disk is a 100 MB Jasmine,
I have set the memory allocated to the Finder to be 300 KB (my desktop file
climbs to nearly 200 KB at times).
I had no problems beyond the odd system bomb running at 2.5 MB of memory
with chip combination (1) and (2) above. I did remove the correct
resistors for the initial upgrade to 2.5 MB.
Upon replacing set (1) with set (3) to go to a full 4 MB, I found that a
host of problems appeared. I would get system bombs with ID's of -2, -3,
-10, -25, etc at odd times within an application or within Finder. Bootup
would sometimes be successful, sometimes yield the various system
bombs, and sometimes yield a sad Mac with various codes starting with 0F.
Some I remember are 0F0003, 0F0016 and 0F0021. This occurred no matter
whether chip set (2) was in Bank A and chip set (3) was in Bank B or vice versa.
Running the Hypercard memory hog provided new errors. I would get sporadic
messages from Hypercard that it did not understand Mouse Location, or
Continue statements. In the latter case, it never returned control to me.
I backed off to the 2.5 MB configuration, utilizing chip sets (1) and (3).
All errors disappeared, and the system operated flawlessly. Several days
later, I installed the other 2.5 MB configuration, utilizing chip
sets (1) and (2). Again, no errors over several days of operation.
Thus I am left with the suspicion that my ROM version will not support a 4MB
configuration! Any knowledgable comments will be greatly appreciated.
Ed Olsen
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