VME bus

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VME bus Trademark; Acronym for Versa Module Eurocard, originally Motorola Versabus. A highly versatile asynchronous backplane bus (IEEE-P1014) that facilitates construction of digital systems from system modules such as processor, memory, disk controller, and external interfacing cards. Data transfers are made by way of a 16- or 32-bit data bus nonmultiplexed with a 32-bit data bus. Transfers are controlled by handshaking interaction of request and acknowledge signals between the current bus master and the addressed slave device. Any intelligent connected device may request bus mastership, which then enables it to initiate data transfers; contention between requesting devices is resolved by a two-level priority bus arbitration system. A flexible prioritized interrupt-handling scheme is also included to enable devices to demand attention from the processor or other designated interrupt-handling device.