MEMORY SYSTEM WITH BACKUP FUNCTION

PURPOSE:To facilitate the automatic transfer to a backup mode at the time of a power failure and eliminate an exclusive circuit in a memory module and reduce the size of the memory module. CONSTITUTION:Among memory modules 5-8 mounted on a master board 10 to which a power is supplied from a main power supply 11, a memory module 5 with a backup function is automatically decided by microprogram control and registered in a control register which is provided so as to correspond to the memory modules. At the time of a power failure, the mode is automatically switched to a backup mode (self-refresh mode) by referring to the control register in accordance with a change in a power failure interrupting signal line 9.