During the course of the last year I attempted to upgrade the memory in my Macs.  I have no electronics background or training, so I was learning as I went.

Starting off with a little research.  The upgrade can be similar for both models; open the case, switch the simms and cut a resistor.  Later models of the SE had a jumper you could change instead of cutting the resistor.  All the notes I ran across, said to cut only one leg of the resistor and move it to make a gap.  That way, if you want to return it to a 1MB system all you have to do is resolder the leg and put the old simms back.

I bought four 1MB simms on ebay and a long torx bit.

My Mac SE has a Prodigy SE upgrade by SuperMac.  The upgrade has a 68020 and 2MB of ram.  I opened up the SE and looked at the Prodigy board and the memory was soldered to the board as far as I could tell.  I closed it up and moved on to the Mac Plus.

I switched the memory, cut the resistor and put it all back together.  When I started it up, all seemed fine for a few minutes, then I got a Sad Mac error 0F0003.  Looking on the internet I found this code broken down  into 0F Exception (or software error), 0003 Illegal Instruction, which didn’t make any sense to me.  The Mac Plus worked fine before changing the memory, but the software kept crashing afterword.

The memory upgrade was a failure. I started looking for a replacement Mac Plus and found a working one that did not have a keyboard or mouse.  This worked out for me with a non working Mac, that I could borrow the keyboard and mouse from.

Last Update: 27-Aug-15