STE SIMM Memory Upgrade

NOTE: Before you start, consider the dangers of static electricity. Remove all cables, and ground yourself. Be careful as to not destroy any components with a static discharge. Handle electronic components with care.

Removing the case

Turn your computer upside down, remove all screws, even the three holding the floppy. Note where the screws are located since they are of different length & dimensions. If you are not careful you’ll end up with screws going through the plastic enclosure.

Turn the STE back. Now you can remove the upper part. Remove the keyboard, you don’t have to disconnect it. Internally the STE is covered with shielding plates. It consists of 4 parts. Remove the one covering the floppy. To the left of the floppy remove the plate covering the SIMM sockets.

Installing the SIMM's

As you can see after removing the shielding of your STE, it is equipped with 4 SIMM sockets. Depending on your model and/or previous uppgrade, 2 or 4 of these are already populated. In this guide we will number the sockets 1 thru 4, with number 1 closest to the back, and number 4 being the one closest to the front of the STE. SIMMs in the STE are always installed in pairs. With 2 identical SIMMs in socket 1 & 3 (memory bank 0), or 2 & 4 (memory bank 1).

Most SIMMs work, although the STE can only use 256kb & 1 mb SIMMs. Parity is not used in the STE and SIMMs with parity work as well, but have been known to cause problems for some. The speed should be 120ns or faster, usually speed is not a problem, since slower SIMMs are somewhat rare.

The following memory configurations are possible: 512kb, 1mb, 2mb, 2,5mb (See note) & 4 mb.

Desired
 Memory    SIMM      SIMM      SIMM      SIMM
  Size    Socket 1  Socket 2  Socket 3  Socket 4

  512KB    256KB     empty     256KB     empty
   1MB     256KB     256KB     256KB     256KB
   2MB     1MB       empty     1MB       empty
   4MB     1MB       1MB       1MB       1MB
  2.5MB    1MB       256KB     1MB       256KB

Important notes:

Going all out with 4mb is really nice, and since SIMMs are abundant today it is cheap too. But keep in mind, that due to some programmers lack of understanding of the hardware, some software (mostly older games) will accidentally write past the 4mb barrier, which causes a hard bus error. So, if some apps/games stops working after the upgrade, just yank 2 mb out and you’ll be safe. This ”bug” is not STE specific, it applies to all STs as well.

NOTE: After you have installed 2.5mb in your STE, it will not configure memory correctly. Your STE will actually believe it has 4mb. If this is a bug in TOS, or because the MMU officially doesn’t support 2.5mb, I’ll leave for others to decide. A program called simmfix exists to fix this, and if you do not apply it right after boot, you will find that your STE crashes very easily, in fact, I’d be surprised if you can do anything but look at the desktop without it crashing.

Text originally from PDF by Greenious

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