Task: Upgrade a Macintosh LCIII Computer to 36MB of RAM
Needed: Mac LCIII or Equivalent Performa Model, 72-Pin 32MB SIMM Card
Time: 15-30 Minutes
Introduction
I acquired a Macintosh LCIII several years ago from a local contact. The first thing I did was replace the leaking capacitors that are common to all Macs of the 1990s. I have previously described how to do this.
The Mac LCIII came out in 1993 and was sold through 1994 mostly to schools. It came with a Motorola 68030 processor and 4MB of onboard memory. Mine came with an additional 72-pin 8MB SIMM card for a total of 12MB of RAM. I decided to upgrade it to the full 36MB of RAM by adding a 32MB SIMM card.
Instructions
First, purchase a 72-pin 32MB SIMM card that is compatible with the Mac LCIII. I got mine from MemorMasters on eBay for $12. Compatibly includes 72 pins, non-parity, and faster than 100 ns.
Second, open the Mac LCIII by gently releasing tabs on the back of the top case cover and slide it forward revealing the circuit board and other components such as the floppy drive, power supply, and hard disk.
Third, locate the 72-pin slot on the front right side of the circuit board (just behind the fan) as you face the front of the computer. There is no need to remove the circuit board from the case.
Fourth, remove the existing SIMM if there is one by carefully moving back the metal tabs holding it in place. Then insert the new 32MB SIMM in the left (back in photo below) slot at a slight angle with notch to the left. Gently tilt the SIMM to toward the back of the computer until the silver metal clasps lock it in place.
Fifth, reassemble the top case applying gentle pressure to the clips in thew back that hold it down. They can break so be careful.
Sixth, power up the Mac and open the About window from the Apple icon to see the new RAM total. It should have a number just about 36,000KB as shown below.
Comments
This is a simple and inexpensive upgrade that will open the door to higher memory games and software. Well worth the effort!
I performed this upgrade to in celebration of #MARCHintosh 2026.
