HP QMS 1660E - Manual (Page 159)

Single In-Line
Memory
Modules
6-25 Printer Options
3 Replace the printer cover.
Lower the printer cover, and position it firmly on the printer. Then
secure the cover to the printer by replacing the two screws you
removed earlier.
4 Reconnect all interface cables and the power cord, and then
turn on the printer.
Single In-Line Memory Modules
Single in-line memory modules (or SIMMs) are compact circuit
boards with surface-mount memory chips. Your printer comes in one
of the following configurations:
n
12 MB RAM—one 4 MB and one 8 MB SIMM
n
24 MB RAM—one 8 MB and one 16 MB SIMM
n
48 MB RAM—one 16 MB and one 32 MB SIMM
However, you can replace one or both of the SIMMs to upgrade the
RAM to as much as 64 MB. SIMMs are available in 4, 8, 16, and 32
MB sizes.