Path: utzoo!attcan!uunet!csdev!ll1a!spl1!laidbak!att!rutgers!mailrus!tut.cis.ohio-state.edu!accelerator!baloo.eng.ohio-state.edu!abali
From: abali@baloo.eng.ohio-state.edu (Bulent Abali)
Newsgroups: comp.sys.next
Subject: Re: NeXT Memory - No Error Checking or
Message-ID: <8735@spl1.UUCP>
Date: 3 Nov 88 22:02:16 GMT
References: <549@gt-eedsp.UUCP> <207400001@inmet> <956@accelerator> <553@gt-eedsp.UUCP>
Sender: news@spl1.UUCP
Reply-To: abali@baloo.eng.ohio-state.edu (Bulent Abali)
Organization: Ohio State Univ, College of Engineering
Lines: 14

In article <553@gt-eedsp.UUCP> jensen@gt-eedsp.UUCP (P. Allen Jensen) writes:

>According to the NeXT salesperson I talked to, the reason was COST not
>performance.  

Adding SEC/DED increases DRAM cost by 7/32, less than 25%. 
Adding parity per 32 bits increases DRAM cost by 1/32, about 3%.
Adding parity per byte increases DRAM cost by 1/8, 12.5%.
 
>I am not an expert on memory hardware, but it doesn't seem
>reasonable to me that parity should cause a performance hit.

I am not an expert on memory hardware either, but I know that
parity and ECC does cause a performance hit.