Macintosh SE Memory Upgrade Guide
The Macintosh SE takes 30-pin SIMMs in four sockets and supports a maximum of 4 MB.[1] Machines shipped with either 1 MB or 2 MB fitted.[1]
Which logic board do you have?
[edit | edit source]This matters, because the two board revisions are configured differently.[1]
- Resistor boards (earlier). A solder-type resistor identifies the memory configuration: R35 is fitted for 1 MB and R36 for 2 MB. In Apple's hardware documentation these are the 256K BIT (R35) and ONE ROW (R36) positions in the RAM SIZE area.[2]
- Jumper boards (later). A jumper in one of two positions, labelled 2/4M and 1M, does the same job.[2]
Memory specifications
[edit | edit source]- SIMM type: 30-pin, 150 ns or faster; the −xx suffix after the manufacturer's part number gives the speed, so −15 is a 150 ns part.[1]
- Eight RAM ICs per SIMM. A nine-chip module works but the ninth device is not connected.[2]
- SIMMs go in rows of two; a row is either empty or full.[2]
- All the RAM ICs in a row must be the same size and speed.[2]
- On a resistor board the larger SIMMs go in row 1; on a jumper board they go in row 2.[2]
- Maximum: 4 MB.[1]
Upgrades, by board type
[edit | edit source]Resistor board
[edit | edit source]Clip one end of resistor R35 or R36 and bend the resistor away from the clipped lead — clipping rather than desoldering lets it be tacked back later.[1]
- 2.5 MB: two 1 MB SIMMs in slots 1 and 2, two 256K SIMMs in slots 3 and 4.[1]
- 4 MB: four 1 MB SIMMs in slots 1 to 4.[1]
Jumper board
[edit | edit source]- 1 MB to 2.5 MB: remove the two 256K SIMMs from slots 3 and 4, fit two 1 MB SIMMs there, and remove the jumper permanently.[1]
- 1 MB to 4 MB: remove all four 256K SIMMs, fit four 1 MB SIMMs, remove the jumper permanently.[1]
- 2 MB to 2.5 MB: fit two 256K SIMMs in slots 1 and 2 and remove the jumper permanently.[1]
- 2 MB to 4 MB: fit two 1 MB SIMMs in slots 1 and 2 and remove the jumper permanently.[1]
Apple's note: disregard the "2/4 M" label silkscreened on the board. A 4 MB upgrade requires the jumper to be removed.[1]
_Guide.png)
_Guide.png)
Tools
[edit | edit source]- T15 Torx screwdriver (long shaft)
- Case separator or plastic spudger
- Anti-static wriststrap
- Matching 30-pin SIMMs
See Recommended Tools.
Procedure
[edit | edit source]1. Prepare. Power off, unplug, work on a grounded surface.
2. Open the case. The machine contains a CRT: read CRT Discharge Procedure, discharge the CRT to the ground lug before disconnecting anything, and do not fit a grounding wriststrap until after it has been discharged. Apple warns that failing to discharge first can damage the logic board or the analogue board.[1]
3. Withdraw the logic board from the bottom of the chassis to reach the sockets.
4. Remove the existing SIMMs. The retaining clips snap easily; ease them outward gently.
5. Fit the new SIMMs with the notch matched to the socket keying, filling complete rows.
6. Set the resistor or jumper for the new configuration before reassembly.
7. Reassemble and verify the memory figure at startup.
Common problems
[edit | edit source]| Symptom | Likely cause | Action |
|---|---|---|
| Sad Mac, or a chime followed by nothing | Wrong, faulty or partly seated SIMMs | 30-pin, 150 ns or faster, eight-chip, non-parity, fully seated |
| Sad Mac with the memory jumper suspected | Configuration not set | Apple's own chart says to verify the three-pin jumper is configured correctly before replacing anything[1] |
| Memory figure unchanged | Resistor still fitted, or jumper still installed | Clip R35/R36, or remove the jumper, as above |
| Half the expected memory | A row is half-populated, or the larger pair is in the wrong row | Fill rows completely and observe the row rule for your board type |
Sad Mac codes are decoded on Sad Mac Error Codes and with the Sad Mac Decoder. Apple's chart also points at individual SIMMs for particular codes.[1]
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Apple Computer, Macintosh SE Service Source — Specifications (Memory) and Upgrades (Memory Upgrade) chapters. Hosted on this wiki: File:Macintosh se.pdf.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Apple Computer, Guide to the Macintosh Family Hardware, 2nd edition, Addison-Wesley, 1990, Chapter 5 "Memory", pp. 196–198 — SIMM rules, RAM SIZE resistors and the later jumper for the Macintosh SE.