VERSAbus
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 minicomputers 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 addresses (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 cards, in common with many card systems of that era (such as DEC 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.
External Links
- VERSAbus Specification Manual
- VERSAbus - a multiprocessor bus standard - and VMEbus - its Eurocard counterpart
- Installing/Operating 4.3BSD - contains a moderately detailed description of the VERSAbus
