A Single In-line Memory Module or SIMM is a small printed circuit board containing memory chips (DRAMs). Most SIMMs have 30 or 72 pins (which are actually printed circuit contacts and not pins). 30-pin SIMMs come in 8-bit (non-parity) or 9-bit (parity). 72-pin SIMMs are generally available in 32-bit (non-parity) or 36-bit (parity) configurations.