Path: utzoo!utgpu!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!pacbell!pbhya!whh
From: whh@pbhya.PacBell.COM (Wilson Heydt)
Newsgroups: comp.sys.next
Subject: Re: NeXT Memory - No Error Checking or
Message-ID: <21157@pbhya.PacBell.COM>
Date: 3 Nov 88 06:01:16 GMT
References: <549@gt-eedsp.UUCP> <207400001@inmet>
Organization: Pacific * Bell, Oakland, CA
Lines: 25

In article <207400001@inmet>, callen@inmet writes:
> 
> I am under the (possible wrong) impression that soft memory errors are
> often caused by cosmic rays streaking through one of the cells in a DRAM 
> and discharging it, and that higher density memories are MORE susceptible
> to this type of error. Is there a memory expert listening who can comment?

I *not* an expert, but I did read a very good article in SciAm a couple 
of years ago on the subject.

According to the article, the primary cause of soft errors comes from the
trace impurities of heavy nuclei in the plastic package.  (Ceramics,
by-the-bye are worse in this context.)  The ones to worry about are
alpha emitters, like Uranium and Thorium.

One can just see a new industry sprining up . . . high-purity plastics
for encapsulating memory chips, with guarenteed low levels of alpha-emtters.

   --Hal

=========================================================================
  Hal Heydt                             |    "Hafnium plus Holmium is
  Analyst, Pacific*Bell                 |     one-point-five, I think."
  415-645-7708                          |       --Dr. Jane Robinson
  {att,bellcore,sun,ames,pyramid}!pacbell!pbhya!whh