Two versions of this card exist. One is designed for use with the A500 and other is designed for use with the A500+. Both cards use 30pin SIMMs however the A500 versions only has two SIMM sockets and the A500+ versions has four. The boards were originally designed to use 256k 30pin SIMMS, however they may support SIMMs of higher values but this is unconfirmed. The cards plug into the trapdoor expansion slot of the A500 and A500+

Thanks to Will Swann