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Path: utzoo!watmath!clyde!rutgers!cbmvax!grr
From: grr@cbmvax.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: 2 meg chip ram
Message-ID: <1423@cbmvax.cbmvax.cbm.UUCP>
Date: Tue, 17-Feb-87 05:30:05 EST
Article-I.D.: cbmvax.1423
Posted: Tue Feb 17 05:30:05 1987
Date-Received: Wed, 18-Feb-87 04:01:15 EST
References: <2438@jade.BERKELEY.EDU> <1375@cbmvax.cbmvax.cbm.UUCP> <7@ethz.UUCP>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 22

In article <7@ethz.UUCP> claudio@ethz.UUCP (Claudio Nieder) writes:
>
>According to the AGNUS PIN ASSIGNMENT printed on page C-2 of the Amiga
>Hardware Reference Manual Agnus has two VSS pins (27,41). Is there
>really no way to use one of these to add an additional address line ?
>				claudio

You ever try to take a ground pin away from a chip guy?  Seriously, lead-frame
impedance to ground is a serious problem with LSI chips.  The more bus lines
you push around, the greater the ground noise seen at the die.  This can lead
to glitches on the both the signals generated by the chip, and the chips's
perception of external signals.

As a result, you see packages with multiple ground and power pins and also
a tendency to shift the power and ground pins towards the center of long,
skinny packages.  How many pins you allow is often rule-of-thumb or how many
are available, although design rules for gate arrays do give more specific
guidelines - lots of pins!
-- 
George Robbins - now working for,	uucp: {ihnp4|seismo|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)