Multibus

Multibus is a computer bus standard developed by Intel in the early 1970s to support modular, backplane-based computer systems. It defined a common electrical interface, connector, and protocol so plug-in boards from different vendors could operate in a compatible system. The goal was to create an open ecosystem for peripheral devices, memory, and I/O that could be used across a family of Intel-based machines as well as third-party products.

The bus uses a backplane with standardized edge connectors and a set of signals for data, addresses, and control. Typical implementations offered an 8-bit data path with a wider address space, and included basic bus arbitration, interrupt signaling, and I/O addressing mechanisms. Boards plug into the backplane and share the bus with other modules; power distribution and signaling were standardized to simplify interchange.

Multibus gained widespread use in the 1970s and early 1980s in industrial computing and hobbyist market segments, including Intel’s own iSBC line and various third-party systems. It competed with other bus architectures of the era, notably the S-100 bus, and fostered a large ecosystem of compatible boards. Intel later introduced Multibus II, a revised version intended to extend bandwidth and capabilities while preserving compatibility with Multibus-era devices.

Over time Multibus declined as newer buses such as ISA, VMEbus, and PCI offered higher performance and broader standards support. Nevertheless, Multibus left a lasting impact on early microcomputer design by promoting modular, plug-in expansion and interoperability among a diverse range of boards and systems.