memoryboard

A memoryboard is a circuit board that provides additional volatile memory to a computer or electronic system. It is typically a plug-in daughterboard that connects to a backplane or system bus and is distinct from the main motherboard. Memoryboards are designed to increase the system’s RAM capacity by adding memory modules on a separate board.

A memoryboard usually carries memory devices such as DRAM or SRAM and may include supporting circuitry such as a memory controller, address and data buffers, decoders, timing logic, and parity or ECC logic. The exact composition depends on the era and architecture; some boards rely on the host system’s memory controller, while others include on-board logic to interface with the bus.

Historically, memoryboards were common in mainframes, minicomputers, and early personal computers, where backplanes and modular expansions made it feasible to scale memory by inserting additional boards. They often required careful compatibility with bus standards, word width, and voltage levels of the host system.

In many modern systems, memory expansion is achieved through standardized memory modules (such as DIMMs or SIMMs) mounted directly on the motherboard or on specialized risers in servers and blade systems. Memoryboards persist in certain contexts, particularly in ruggedized or legacy equipment, embedded systems, or long-lived backplane-based installations where modular expansion remains practical.

Variants and related terms include RAM cards and memory expansion cards. In practice, a memoryboard is a broad term for a board that adds RAM, while DIMMs, SIMMs, and other modules describe the current standardized forms of memory used in contemporary hardware. See also backplane, memory module, ECC, DIMM, and SIMM.