This is an 8K Memory Module.
The Memory Module stores the user control program. The green status LED, labeled PASS, located on the front of the module energizes after successful completion of the module self-test. The memory module is positioned in cardrack slot C in the 620-25 and E of the 620-35.

Additional memory modules can be inserted in option slots A – B in the 620-25 or slots A – D in the
620-35 to increase memory capacity to 32K. The memory starting address must be set for each module, forming contiguous memory space in order for a complete memory scan to occur during operation.