5.   Locate the correct socket group for the type of SIMM you are installing.   There are two socket groups: one contains two sockets, the other contains four sockets.   The
DRAM SIMMs (memory) must be installed in one of the sockets in the socket
group of two.   The IPDS SIMM, PostScript SIMM, and the flash memory SIMMs
must be installed in one of the sockets in the socket group of four. Note:   Early printers may have the PCL5e SIMM already installed in socket 0.   If
the SIMM is not installed, PCL5e data stream support is integrated into the
controller card. 102 User’s Guide