Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!lll-winken!lll-tis!ames!mailrus!tut.cis.ohio-state.edu!cwjcc!hal!nic.MR.NET!shamash!nis!meccts!meccsd!mvs
From: mvs@meccsd.MECC.MN.ORG (Michael V. Stein)
Newsgroups: comp.sys.next
Subject: Re: NeXT Memory - No Error Checking or Parity !
Keywords: Memory,errors,parity
Message-ID: <1097@meccsd.MECC.MN.ORG>
Date: 30 Oct 88 05:53:50 GMT
Article-I.D.: meccsd.1097
References: <549@gt-eedsp.UUCP> <1807@desint.UUCP>
Reply-To: mvs@meccsd.UUCP (Michael V. Stein)
Organization: Minn. Educ. Comp. Corp.
Lines: 18

In article <1807@desint.UUCP> geoff@desint.UUCP (Geoff Kuenning) writes:
>CDC made that mistake, too, on the old 6000 series machines.  The way
>I heard it, somebody "discovered" that most of the parity errors on the
>3000 series were in the parity bits themselves.  So dropping the parity
>bits would not only save money, but would cut pointless downtime.

I'm almost positive that old CDC machines had no form of parity bits.
I am positive that our old Cyber 73 had no parity.  

>I think
>(though I'm not sure) that they installed parity again on the 7600.

All of the later CDC machines had full SECDED (Single Error Correction
Double Error Detection) support.  This meant that all of the 60 bit
words had an extra 11 bits of SECDED data associated with it.

-- 
Michael V. Stein - Minnesota Educational Computing Corp. - Technical Services
{bungia,uiucdcs,umn-cs}!meccts!mvs  or  mvs@mecc.MN.ORG