Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!uwm.edu!ux1.cso.uiuc.edu!mp.cs.niu.edu!bennett
From: bennett@mp.cs.niu.edu (Scott Bennett)
Newsgroups: comp.sys.next
Subject: Re: Spotted Workspace ? Why? (and BlastApp??)
Keywords: memory errors, non-parity memory, spotted display
Message-ID: <1991Apr8.014743.25515@mp.cs.niu.edu>
Date: 8 Apr 91 01:47:43 GMT
Article-I.D.: mp.1991Apr8.014743.25515
References: <1991Apr5.075135.23325@cs.ubc.ca> <1991Apr6.043551.29580@mp.cs.niu.edu> <1991Apr6.205555.21974@cbnewse.att.com>
Organization: Northern Illinois University
Lines: 65

In article <1991Apr6.205555.21974@cbnewse.att.com> tyc@cbnewse.att.com (felix.a.lugo) writes:
>In article <1991Apr6.043551.29580@mp.cs.niu.edu> bennett@mp.cs.niu.edu (Scott Bennett) writes:
>| In article <1991Apr5.075135.23325@cs.ubc.ca> sritchie@cs.ubc.ca (Stuart Ritchie) writes:
>| >In article <1991Apr3.230504.27819@mp.cs.niu.edu> bennett@mp.cs.niu.edu (Scott Bennett) writes:
>| >>In article <5596@media-lab.MEDIA.MIT.EDU> simsong@daily-bugle.media.mit.edu (Simson L. Garfinkel) writes:
>| >If software still runs, it sounds to me like the VRAM is shot.
>| >   [text deleted  --SJB]
>| >
>	What a load of s..t!  Do you really believe that you have a toy
>	computer just because it doesn't have parity VRAM?  How many parity

     Well, I supposed having the *displayed image* damaged is not as
bad as having data in main memory damaged, but it *would* be irritating,
especially if it made it difficult to communicate with the software.

>	erros have you seen recently in "production" systems that cause all
>	your work to get lost when the system decided that it could no longer
>	continue?  Parity RAM does nothing to a system unless it contains some
>	ECC logic to correct the problem.  Parity RAM only informs the system

     (one more time, sigh)  First, yes, I see single-bit errors frequently
enough on equipment that is capable of detecting them.  However, even
systems that have parity, but not ECC, memory are able to make use of
the information.  For example, a data page that has not been modified
since its last pageout or a text page can be refreshed from a file or
a paging area.  In the case of a dirty data page, the kernel/supervisor
can terminate the affected program.  If the damage is in a kernel page,
then the choice of solutions can be a bit more complex, but more times
than not a well written system can make repairs and continue.  Repairs
should include, of course, marking the affected block of memory as
being unusable, so that it can't cause any more problems as long as the
system stays up and running.

>	that some memory has gone bad.  Would you like your NeXT to shutdown
>	because you have a fault in you VRAM?  I certainly would not!!!!!

     Of course not, but it would be nice to have the errors logged.
Logging the errors makes it easier to know what needs to be fixed.
>
>| 
>/*
>** ============================================================================
>**
>**  Felix A. Lugo
>**
>**	E-Mail (including NeXTMail):
>**			Felix_A_Lugo@ATT.COM
>**			att!ihcoco!coco
>**
>** ============================================================================
>*/


                                  Scott Bennett, Comm. ASMELG, CFIAG
                                  Systems Programming
                                  Northern Illinois University
                                  DeKalb, Illinois 60115
**********************************************************************
* Internet:       bennett@cs.niu.edu                                 *
* BITNET:         A01SJB1@NIU                                        *
*--------------------------------------------------------------------*
*  "Well, I don't know, but I've been told, in the heat of the sun   *
*   a man died of cold..."  Oakland, 19 Feb. 1991, first time since  *
*  25 Sept. 1970!!!  Yippee!!!!  Wondering what's NeXT... :-)        *
**********************************************************************