View source for VERSAbus

[[Image:VERSAbus memory card.jpg|thumb|right|250px|VERSAbus memory card from Motorola Microsystems]]

The '''VERSAbus''' [[bus]] was created in 1979 by [[Motorola]], initially for use on [[Motorola MC68000]]-based systems. Although it was not used by many products (although the [[Power 6/32‎]] did), it was influential as the basis for the electrical functionality of the [[VMEbus]], used in many [[minicomputer]]s and specialist computers.

The VERSAbus had fairly ambitious goals when it was defined. In addition to immediate goals, it also put a fair amount of thought into long-term evolution; it was therefore an [[asynchronous]] bus. It was more powerful than most [[microcomputer]] buses at the time; it had a maximum 32-bit-wide [[data path]], and could use 16-bit, 24-bit, or 32-bit [[address]]es (see the [[4.3 BSD Reno]] document for a quick overview of the details). It also made provisions for sequential address access, to maximize performance; it also provided for a discrete priority [[arbitration]] unit, to allow use in [[multi-processor]] systems. Since the VERSAbus was principally used as an [[input/output]] bus, it also supported a fairly comprehensive [[interrupt]] structure.

VERSAbus [[printed circuit board|cards]], in common with many card systems of that era (such as [[Digital Equipment Corporation|DEC]] [[DEC card form factor|standard cards]]), used [[etch]] fingers on one edge of the card, to make electrical contact with the bus; they measured 14.5 by 9.25 inches.

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== External Links ==

* [https://bitsavers.org/pdf/motorola/versabus/M68KVBS_VERSAbus_Specification_Manual_Jul81.pdf VERSAbus Specification Manual]
* [https://www.sciencedirect.com/science/article/abs/pii/0141933182904902 VERSAbus - a multiprocessor bus standard - and VMEbus - its Eurocard counterpart]
* [https://www.tuhs.org/cgi-bin/utree.pl?file=4.3BSD-Reno/src/share/doc/smm/01.setup/tahoe/1.t Installing/Operating 4.3BSD] - contains a moderately detailed description of the VERSAbus

[[Category: Buses]]