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From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: comp.sys.next
Subject: Re: NeXT Memory - No Error Checking or Parity !
Keywords: Memory,errors,parity
Message-ID: <17803@glacier.STANFORD.EDU>
Date: 28 Oct 88 17:02:48 GMT
Article-I.D.: glacier.17803
References: <549@gt-eedsp.UUCP> <1807@desint.UUCP>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 21


      It's not that "the machine might crash".  It's that one might get
bad data and not know it.  Particularly in applications with long-lived
databases updated over time, any source of undetected error is intolerable.
Corrupted program objects might be generated.

      Some early MS-DOS machines, such as the Texas Instruments TI PRO,
lacked memory parity.  I at one time had one of these machines.  The
usual symptom of memory trouble was not a system crash, but junk in
newly compiled and linked executables.  It's really bad when you have
to compile the same program twice and compare the executables to insure
that the compile and link were successful.

      That TI PRO became a doorstop in late 1984.

      The Mac II doesn't have memory parity either.  A bad move by Apple.

      I consider a machine without memory parity unacceptable for serious
work.  But then, NeXT is targeting the educational environment.

					John Nagle