Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!zaphod.mps.ohio-state.edu!sdd.hp.com!hp-pcd!hpcvca!charles
From: charles@hpcvca.CV.HP.COM (Charles Brown)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Parity Checking / ECC RAM on the A3000
Message-ID: <1410048@hpcvca.CV.HP.COM>
Date: 12 Jun 90 00:56:28 GMT
References: <1990May27.101258.24470@zorch.SF-Bay.ORG>
Organization: Hewlett-Packard Co., Corvallis, Oregon
Lines: 34

>> If the ECC RAM returns the correct value but too late, it is not
>> designed correctly.  Part of the task of design is to make sure there
>> is enough margin.  So you have not demonstrated your point.  What you
>> have demonstrated is that: Poorly designed ECC RAM is sometimes less
>> reliable than well designed RAM w/o ECC.  So what.

>      Way off... With modern memory parts everything is quantitized and
> statistical since the charges being moved are on the order of 20,000
> times the charge of an electron.  In theory (but very, very rarely)
> sometimes you will get no electons willing to move and read a one as a
> zero.
      ... [lots of irrelevant details deleted]
> 					Robert I. Eachus

If you put ECC into your RAM system, you must use faster RAM chips to
achieve the same overall system RAM speed.  This is to allow the ECC
circuitry time to make an corrections.  The effective sample time
coming out of the RAM is different for the two systems in order to get
the same effective system RAM access time.  The reliability of the
data coming out of the fast RAM chips at their spec access time will
be approximately the same as the reliability of the data coming out of
the slower RAM chips at their spec access time.  Quantization is
irrelevant (and probably not a factor anyway).

But all of this arguing is silly.  As others have pointed out the main
reliability concern in the Amiga is the software.  It really makes
little sense to worry about rare problems such as bad RAM data when
the software is typically so poor.  I assume you agree with this
statement.  In any case I will discontinue bickering about ECC.  It is
just not very important.
--
	Charles Brown	charles@cv.hp.com or charles%hpcvca@hplabs.hp.com
			or hplabs!hpcvca!charles or "Hey you!"
	Not representing my employer.