Zorro (expansion)
Introduction
The Zorro expansion bus is an extension of the CPU bus with the addition of clock signals and special control signals for memory expansion. There are 3 different versions of the Zorro bus which have been used in Amiga computers since the A1000.
Zorro (AKA Zorro I)
The first version of the Zorro bus was specified in the Schematics and Expansion Specifications book. It took all the signals from the A1000 expansion connector and provided a backplane with 5 buffered 100 pin slots. The additional signals allowed for controlling the bus. Dedicated PAL chips were used for bus arbitration, collision and steering. Commodore never officially released an expansion box but Amiga's engineers in Los Gatos worked with Byte by Byte on developing the PAL and PAL Jr. boxes, which used this version of the Zorro bus.
Zorro II
Zorro II first appeared on the A2000. The circuitry on the first expansion backplane was integrated into one board.
Zorro III
Zorro III was a true 32-bit version of the Zorro II bus and introduced with the A3000. It was designed by Dave Haynie.
References
- Amiga Hardware Reference Manual, 3rd Edition
