Macintosh SE/30 Memory Upgrade Guide

The Macintosh SE/30, introduced in 1989, was the most powerful compact Mac of its era. It features an expandable RAM up to 128 MB with the correct SIMMs. Originally, the SE/30 shipped with 1 MB of RAM, but it can be upgraded significantly for better multitasking and performance.

Memory Specifications

The Macintosh SE/30 features 8 30-pin SIMM sockets, organized into two banks of four. Memory must be installed correctly for proper functionality:

Bank A (Front 4 slots) – Must always be populated first.
Bank B (Rear 4 slots) – Can be left empty unless installing more than 4 MB of RAM.

The SE/30 supports memory interleaving, meaning matched SIMMs provide better performance.

**Macintosh SE/30 RAM Configurations**
Total RAM	Bank A Configuration	Bank B Configuration	Individual SIMM Capacity
1 MB (stock)	4 × 256 KB	Empty	256 KB
2 MB	4 × 256 KB	4 × 256 KB	256 KB
4 MB	4 × 1 MB	Empty	1 MB
5 MB	4 × 1 MB	4 × 256 KB	Mixed (1 MB & 256 KB)
8 MB	4 × 1 MB	4 × 1 MB	1 MB
16 MB (May not work)	4 × 4 MB	Empty	4 MB
17 MB	4 × 256 KB	4 × 4 MB	Mixed (256 KB & 4 MB)
20 MB	4 × 4 MB	4 × 1 MB	Mixed (4 MB & 1 MB)
32 MB	4 × 4 MB	4 × 4 MB	4 MB
64 MB	4 × 16 MB	Empty	16 MB
128 MB (Maximum)	4 × 16 MB	4 × 16 MB	16 MB

Important Notes:

The SE/30 reserves 1 MB of RAM for video memory, meaning the 17 MB configuration (256 KB in Bank A, 4 MB in Bank B) is recommended for best performance.
If using 16 MB SIMMs, they must be non-parity and low-profile to fit properly.
Apple never officially documented configurations beyond 32 MB, but 64 MB and 128 MB work when using non-parity 16 MB SIMMs.

Required Tools

To upgrade the Macintosh SE/30 memory, you will need:

Torx T15 screwdriver (for case removal)
Plastic spudger or pry tool (to carefully separate the case)
Anti-static wrist strap (to prevent electrostatic discharge)
Compatible 30-pin SIMMs (matching capacity and speed)

Memory Upgrade Procedure

Step 1: Prepare the Macintosh SE/30 Ensure the Macintosh SE/30 is completely powered off and unplugged. Work on a grounded surface and wear an anti-static wrist strap to protect components from static discharge.

Step 2: Remove the Case Use a Torx T15 screwdriver to remove the four screws securing the rear case. Carefully separate the two halves using a plastic spudger. Be cautious of the CRT, as it retains high voltage even when unplugged.

Step 3: Locate the SIMM Slots The 8 memory slots are on the logic board, organized into two banks:

Bank A – The four front slots (closest to the edge of the board).
Bank B – The four rear slots (closest to the rear ports).

Step 4: Remove Existing SIMMs If replacing existing memory, gently (they easily snap) push apart the retention clips on each side of the SIMM slot and remove the modules.

Step 5: Install New SIMMs Align the new SIMMs with the slots, ensuring the notch matches the keying of the slot. Firmly push down until the SIMM snaps into place.

Installation Rules:

If upgrading to 4 MB, remove all 256 KB SIMMs from Bank A and install 4 × 1 MB SIMMs.
If upgrading to 5 MB, install 4 × 1 MB SIMMs in Bank A and move the 256 KB SIMMs to Bank B.
If upgrading to 17 MB, install 4 × 256 KB SIMMs in Bank A and 4 × 4 MB SIMMs in Bank B to optimize video memory allocation.
If upgrading to 128 MB, install 8 × 16 MB SIMMs (non-parity, low-profile).

Step 6: Reassemble the Macintosh SE/30 Once the memory is installed, reassemble the case and secure it with the Torx screws.

Step 7: Enable 32-bit Addressing (For RAM Above 8 MB) If you install more than 8 MB of RAM, it will be marked as allocated to the system unless Mode32 is installed.

To enable full memory access:

Install Mode32.
Open the Memory Control Panel.
Enable 32-bit addressing.

Common Issues and Troubleshooting

Issue	Possible Cause	Solution
Macintosh SE/30 beeps on startup	Incompatible or faulty SIMMs	Ensure SIMMs are 30-pin, 120 ns or faster, properly seated, and non-parity.
Memory not recognized correctly	Mismatched SIMM capacities	Install matched pairs and avoid mixing different memory sizes.
System crashes or instability	Faulty or damaged SIMMs	Replace with known-good, compatible memory modules.
SE/30 does not boot with 16 MB SIMMs	SIMMs have parity	Use non-parity SIMMs for 16 MB configurations.
RAM over 8 MB is "allocated to system"	32-bit addressing not enabled	Install Mode32 and enable 32-bit addressing in the control panel.

Additional Resources

For further details, refer to: