The Amiga Zorro expansion system was the first expansion system for the home and small business market that allowed virtually limitless expansion possibilities to the Amiga computer systems, while requiring no configuration from the user – simply plug it in and it just worked – this system was called AUTOCONFIG on the Amiga, and it operated much like the Plug and Play system most may be more familiar with.
The original “Zorro” name comes from the code name of one of the Amiga 1000 prototype boards. The “Zorro” board was the one that followed the “Lorraine,” and was the board in the works when much of the expansion specifications were worked up.
The original expansion bus, as used on the Amiga 1000, Amiga 500 and Amiga 500 plus, is a male 86 contact edge connector. It was located on the right hand side of the system unit on the Amiga 1000, and on the left side of the Amiga 500 and the later Amiga 500 plus.
The Zorro II expansion bus was introduced in the Amiga 2000 and is much the same as the expansion bus on the Amiga 1000 and Amiga 500, only it has additional contacts (100 instead of 86) and is a female slot, located within the system unit, which allows more than one expansion without requiring each to be plugged into another. It is possible to construct adapters to allow the connection of Zorro II expansions to an Amiga 1000, Amiga 500 or Amiga 500 plus.
Zorro III was introduced with the Amiga 3000, and was in the Amiga 3000 Tower, Amiga 4000 and Amiga 4000 Tower. It was mainly backwards compatible with the Zorro II expansion standard, but increased the address space in which it could operate, increased the speed and increased the bus width.
Zorro II and Zorro III expansions were designed for the ‘big box’ Amiga machines, such as the Amiga 2000, Amiga 3000 and Amiga 4000, although as noted above, adapters could be made to allow the use of Zorro II expansions with other machines, including the Amiga 500, Amiga 500 plus and Amiga 1200 (usually as part of a ‘tower conversion’). Because autoconfig is in Kickstart from version 1.2 onwards, it can be used by any expansion designed to use it – which is part of the reason why machines such as the Amiga 500 and Amiga 1200 that didn’t have Zorro II slots can utilise Zorro II or even Zorro III expansions if an appropriate adapter is used in the system.