The Simtec 4-8MB ROM RAM board gave Archimedes owners the ability to double the amount of RAM that an Archimedes could support. The memory limit for the Archimedes was defined by an architectural limit of the MEMC chip in that it could address a maximum of 4MB of RAM. The designers at Acorn foresaw that the 4MB limit may be a restriction and so designed the MEMC chip to be able to work in concert using a maximum of 4 MEMC chips providing support for a total of 16MB of RAM.
The Simtec upgrade consists of two carrier boards. The first being the MEMC controller board which requires that the Archimedes' on board MEMC controller is removed from its socket and placed in one of the two sockets o