Ricoh M281 Series Service Manual page 984

Boards
SAF Memory Back-up
A rechargeable battery backs up the SAF memory (DRAM) for 12 hours.
ROM
4 MB flash ROMs for system software storage
SRAM
The 512 KB SRAM for system and user parameter storage is backed up by a lithium battery.
SRAM Back-up
A lithium battery backs up the system parameters and programmed items in the SRAM, in case
the base copier's main power switch is turned off.
Switches
Item Description
SW1 Switches the SRAM backup battery on/off.
CPU
This controls the energy-efficient operation of the FCU board.
D255/D256 FAX OPTION 150 SM