This is the original core memory card for the basic controller. The more recent memory for this controller is the 30735857-001, which uses CMOS memory with a 9V battery backup.

The memory card is used to copy data from a solid state RAM. It is updated every 1/3 seconds. When the controller is started, the contents of the backup are automatically copied into the RAM for the processor to read the data. The board also has one LED that blinks each time data is updated.