NuBus

Available on old Apple Macintosh computers and on NeXT computers. Standard: IEEE 1196

NuBus was a considerable step forward compared to other interfaces of the day. At the time most computer bus systems were 8-bit, as were the computers they plugged into. However NuBus decided on a 32-bit interface because it was clear the market was headed in this direction.

In addition, NuBus was agnostic about the processor itself. Most buses up to this point were basically the pins on the CPU run out onto the backplane, meaning that the cards had to conform to the signalling and data standards of the machine it was plugged into (being little endian for instance). NuBus made no such assumptions, which meant that a NuBus card could be plugged into any NuBus machine, as long as there was an appropriate device driver.

And in order to select the proper device driver, NuBus included an ID scheme that allowed the cards to identify themselves to the host computer during startup. This meant that the user didn"t have to configure the system, the bane of bus systems up to that point. For instance, with ISA the driver has to be configured not only for the card, but for the slot it is plugged into, any memory it needs, and the interrupts it uses. NuBUS required no such configuration, making it one of the first examples of plug-and-play architecture.

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