Xerox C55/C55mp - Manual (Page 127)

O P T I O N A L E Q U I P M E N T 8–7
Memory slots appear as illustrated in Figure 8–1 below when
additional memory has not been installed.
Figure 8–1: The C55/C55mp Printer Memory Board Configuration
When you install additional memory in your printer, the memory
SIMMs should be added in pairs by inserting them into slots
contained in the pull-out panel on the rear of your printer.
NOTE: The C55/C55mp configuration will already have two 8 MB memory
SIMMs installed.