Aaeon SBC-551 Manual page 23

The SBC-551/552 provides two 72-pin SIMM (Single In-line
Memory Module) sockets. The SIMM supports either Fast Page
Mode (FPM) or Extended Data Output (EDO) DRAM with a speed
of at least 70 ns. Depending on the combination of modules you
use, you can install from 4 MB to 128 MB of RAM.
NOTE 1: Pentium or compatible processors adopt 64 bit data bus.
Since 72-pin SIMM can only provide 32 bit data bus
width, two SIMM modules are required as one memory
bank, and both SIMMs must be the same size and type.
1. Ensure that all power sources are disconnected.
2. Slip the memory module into the socket at a 45 degree angle.
3. Push the module toward the vertical posts at both ends of the
socket until the module is upright and the retaining clips at both
ends of the module click into place. When positioned correctly,
the pins on top of the vertical posts should correspond to the
circular holes on the ends of the module.
4. Repeat steps 2 and 3 for each module you install.
NOTE 2: Do not insert any SIMM module that contains more
than 24 memory chips. SIMMs contain more than 24
chips exceed the driving capability of new generation
chipsets.
Chapter 2 Installation 15