SIMM
Single inline memory module. A high-density DRAM package alternative consisting of several components connected to a single printed circuit board.

Parity
A bit added to a group of bits to detect the presence of an error. The parity bit looks at the other 8 bits and determines if they are even or odd and correspondingly is a 0 or 1. The system compares the 8 bits with the parity bit. If they both are even or odd, the data is assumed to be correct. If one is even and one is odd, there is an error, and typically the system will fail.