Newsgroups: comp.sys.next
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: NeXT Memory - No Error Checking or Parity !
Message-ID: <1988Oct31.204747.17184@utzoo.uucp>
Organization: U of Toronto Zoology
References: <549@gt-eedsp.UUCP> <8348@alice.UUCP>
Date: Mon, 31 Oct 88 20:47:47 GMT

In article <8348@alice.UUCP> debra@alice.UUCP () writes:
>NO. (memory is NOT reliable enough)
>
>I have seen memory go bad on ATs, Microvaxen, big Vaxen, ...

You're at Bell Labs CS research, right?  Do you use a Blit/5620/etc.?
If so, unless they've changed the hardware, you're using a machine with
no parity on its memory every day.  Is it a problem?

To expand on some of my earlier comments:

There is no such thing as perfectly reliable memory.  It's all a matter
of how much you want to pay for lower error rate.  If your memory chips
are good enough, parity may be past the point of diminishing returns.
I personally prefer it, but I don't insist on it.

Those who are smug about their PCs having parity might want to consider
three small complications:

1. There is no way for PC software to test the parity machinery, so it
	can go bad without notice.

2. At least one widely-used BIOS implementation has bugs in its handling
	of parity errors.

3. A lot of PC software essentially disables parity-error reporting.

(This is not first-hand information, but it's from a source I consider
quite reliable.)
-- 
The dream *IS* alive...         |    Henry Spencer at U of Toronto Zoology
but not at NASA.                |uunet!attcan!utzoo!henry henry@zoo.toronto.edu