Memory Upgrades: Mac SE

The Mac SE shipped from the factory with 1 MB installed in the form of four 256 KB SIMMs. It can be upgraded to 2 MB, 2.5 MB, and 4 MB configurations using 150ns or faster 1 MB 30-pin SIMMs.

Macintosh SE

Apple warns against using composite SIMMs; you should specify noncomposite SIMMs when buying memory for your Mac. In the SE, SIMMs must be installed in pairs and replace the 256 KB SIMMs already on the motherboard.

You will need a long (at least 6″/15cm) T15 torx screwdriver (such as the Craftsman Professional series T-15 Torx screwdriver, #47431) to remove the screws from the back of the case. Two are near the bottom, two more way down inside the handle. A case cracker is recommended for separating the front and rear of the case, but you can do it without one. Just be careful.

Under no circumstances come into contact with the pins on the back of the video tube. It can packs a punch. Be careful.

Carefully remove the power, floppy drive, and other cables from the motherboard, then slide it out of its mount.

Looking at the motherboard with the connectors away from you, there are four SIMM slots. Bank A is the rear pair of sockets; Bank B is the one nearer the front of the motherboard.

Mac SE memory upgrade

Mac SE (Soldered) page from Apple Memory Guide.

Note that there are two different SE motherboards: one has two resistors (R35 and R36) behind SIMM 1, the other has a jumper marked 2/4M and 1M.

Mac SE memory upgrade

Mac SE (Jumpers) page from Apple Memory Guide.

To upgrade to 2 MB, remove all the 256 KB SIMMs, being careful not to damage the sockets. Replace the ones in Bank A with a pair of 1 MB SIMMs. If you have the resistor motherboard, remove R35 but leave R36 in place. If you have the jumper motherboard, put the jumper in the 2/4M position.

To upgrade to 2.5 MB, remove the 256 KB SIMMs from Bank A, being careful not to damage the sockets. Replace these with 1 MB SIMMs. If you have the resistor motherboard, remove R35 and R36. If you have the jumper motherboard, remove the jumper.

To upgrade to 4 MB, remove all four 256 KB SIMMs and replace them with 1 MB SIMMs, being careful not to damage the SIMM sockets. If you have the resistor motherboard, remove R35 and R36. If you have the jumper motherboard, remove the jumper. (Oddly, you do not set it to the 2/4M setting.)

Now reseat the motherboard in its mount, reconnect all cables, and test it. (Careful of exposed wires, but nothing worse than getting the whole thing back together and discovering you have a bad SIMM or have not seated the memory correctly.) Boot your SE with extensions off (hold down the shift key) and check “About This Macintosh” under the Apple menu. If it doesn’t read 2,048KB, 2,560KB, or 4,096KB, you’ll need to reseat your memory.

Once you know the upgrade is a success, put the back on your SE, tighten the screws, and enjoy the extra memory. Some suggestions:

  1. If you have a hard drive, increase the size of the disk cache.
  2. If you are floppy based, create an 800KB RAM disk, which is much faster than floppy disks or hard drives.
  3. If you are using System 6 and haven’t used MultiFinder, learn to.
  4. If you haven’t used System 7, get a copy and see how much you like it. (See our links to System 6.0.8 and 7.0.1.)

Recommendations

  • If you have less than 4 MB installed, upgrade to 4 MB. You can often find pulled 1 MB SIMMs (removed from other Macs during upgrade) inexpensively.
  • Memory permitting, set the disk cache to 128KB.

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