Why did the amiga use Zorro instead of ISA and PCI to begin with?

[bloodline]

mantisspider wrote:
@animagic,

efaristo re.
makes sense as it was picked up by the video industry. But still cant see anysense as to why they didnt allow both Zorro and the ISA-bus to be used as standard on the machine. hope these pointless questions dont become one of those that can never get anwsered. i need closure! :-S

Zorro was designed to allow access to the Amiga and it's special hardware... ISA has no ability to do that it lacks the custom chip signals etc...

The Zorro specification grew out of an Expansion slot on the A1000, that was designed to provide a far more flexable interface than ISA was designed to provide. (Zorro and Zorro II are basicly the same thing)

As for Zorro III, there was no PCI or 32bit ISA at the time so the Amiga team had to design their own 32 Bit bus. When PCI was developed the Amiga Design team planned to include it in the next Amiga, but Commodore folded before that ever happened.

[bloodline]

Animagic wrote:
Yes, bloodline is very helpfull most of the time  :-)

That's my pleasure :-) I could bang on about Amiga Hardware until some one leads me back to my padded cell in the mental asylum :-D


Oh and they didn't include ISA as standard, simply becasue they didn't need to! The Zorro bus was fast, more flexable, and the ISA would have required extra hardware (an ISA controler chip etc..). Oh, and the ISA was not Autoconfig, where as Zorro is. AmigaOS (and amiga users) needs Autoconfig devices.