This is the original core memory card used in the Extended controller. This memory is non-volatile, but cannot be used with UAC (Uninnterrupted Antomatic Control).

This memory will hold data if power to system is lost. The board has one LED which blinks each time data is updated. A switch is located on the front of board to allow/disable the automatic update of data. The 'Normal' position allows the updating of data.

This board became unavailable from Honeywell in 1995, replaced by the 30735857-005 CMOS memory board, which requires battery power to retain memory. The CMOS memory is required for UAC.