[comp.sys.amiga] Zorro I vs. Zorro II

phils@tekigm2.TEK.COM (Philip E Staub) (10/27/87)

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Has anyone ever posted a summary of the electrical and mechanical
differences between the Zorro I and Zorro II bus specs? If not, could
someone do so? If so, could someone e-mail me a copy?

Thanks,
Phil

daveh@cbmvax.UUCP (Dave Haynie) (10/27/87)

in article <2337@tekigm2.TEK.COM>, phils@tekigm2.TEK.COM (Philip E Staub) says:
> 
> Has anyone ever posted a summary of the electrical and mechanical
> differences between the Zorro I and Zorro II bus specs? If not, could
> someone do so? If so, could someone e-mail me a copy?
> 
> Thanks,
> Phil

Electrical Differences are simple:

	Pin	Zorro-I		Zorro-II
	 20	RESERVED	 -12V
	 40	/IPL0		 /EINT7
	 42	/IPL1		 /EINT5
	 44	/IPL2		 /EINT4
	 96	RESERVED	 /EINT1

The -12V designation did appear on some later Zorro-I specs.  The "/IPLn"
lines are encoded 68000 interrupt lines that are an input to the 68000
from the Paula chip.  These are inputs only from the point of view of the
PIC.  The "EINTn" lines are unencoded interrupt lines, which may be asserted
with an open collector device on a PIC.

The /IPLn lines in an A2000 are moved to the Coprocessor Slot to support
add-on processors, such as 68020s, the only type of device that's going to
be able to use these signals. 
-- 
Dave Haynie     Commodore-Amiga    Usenet: {ihnp4|caip|rutgers}!cbmvax!daveh
   "The B2000 Guy"              PLINK : D-DAVE H             BIX   : hazy
    "Computers are what happen when you give up sleeping" - Iggy the Cat