Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!uc!nic.MR.NET!ns!logajan
From: logajan@ns.network.com (John Logajan)
Newsgroups: comp.sys.atari.st
Subject: Re: Piggy back DIY upgrades -- don't change those resistors!
Message-ID: <1536@ns.network.com>
Date: 8 Aug 89 04:57:14 GMT
References: <8908070940.AA25858@ucbvax.Berkeley.EDU> <1535@ns.network.com>
Sender: logajan@ns.network.com (John Logajan)
Organization: Network Systems Corp. Mpls MN
Lines: 16

> <8908070940.AA25858@ucbvax.Berkeley.EDU>, AWINFHAH@HMARL5.BITNET writes:
> > The address lines have a 33 ohm series resistor between the MMU and the
> > RAM array. Somebody noted that they are there to limit the current drawn
> > from the MMU. This only partially true. Another (and probably the main)
> > purpose of the resistors is to avoid ringing on the address lines.

Oh, I fogot.  Another reason to use such resistors is to cut down on system
generated EMI (electro-magnetic interference.)  All this electronic equipment
has to meet FCC EMI standards -- and every little bit of attenuation helps.

It stands to reason that if less current initially flows, and ringing is less,
then less EMI will be radiated.

-- 
- John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428  -
- logajan@ns.network.com / ...rutgers!umn-cs!ns!logajan / john@logajan.mn.org -