This is a RAM upgrade that uses a 72pin SIMM to provide a 4MB upgrade for the Acorn Archimedes A3000.

The board just plugs into the RAM upgrade slot of the Archimedes and uses a single-sided FPM 4MB 72pin SIMM to upgrade the machine. It automatically disables the onboard RAM so that all the SIMM RAM is used.

Note: The Archimedes A3000 does not support more than 4MB RAM on the expansion socket, a SIMM larger than 4MB is not expected to work and may actually show as less than 4MB.