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From: rar@auc.UUCP (Rodney Ricks)
Newsgroups: comp.sys.amiga
Subject: Re: multitasking on wallstreet
Summary: IBM PC parity checking isn't so great.
Keywords: IBM PC RAM parity
Message-ID: <32244@auc.UUCP>
Date: 3 Mar 89 04:21:38 GMT
References: <1295@csd4.milw.wisc.edu> <503@morgoth.UUCP>
Reply-To: rar@auc.UUCP (Rodney Ricks)
Organization: Atlanta University Center, Atlanta, Ga.
Lines: 73

In article <503@morgoth.UUCP> steve@morgoth.UUCP (Steve Hall) writes:
>In article 26822, duncan@csd4.milw.wisc.edu (Shan D Duncan) writes:
>> Wall St. money rides on PC's
>> and
>> It's real time on Wall Street
>> 
>[stuff deleted]
>> 
>> Now the questions.  Is there anything a PC with windows can do in this
>> area that the amiga can not (probably cheaper and better) EXCEPT for
>> the non Fortune 1000 image?
>
>Please correct me if I'm wrong (and I very well could be  :-), but I
>thought that there was an inherent problem using non-parity protected
>RAM for doing lots of meticulous financial record keeping.  Something
>about the contents changing...
>
>Mind you, I heard this through someone else and I could be way off
>base.

Actually, I think that you may be.  Parity checking on the IBM PC has a
MAJOR problem.  Say the system finds a parity error.  What does it do; how
does it recover?

Recover, what does recover mean?  If a parity error is found, the system
puts up an error message:

PARITY ERROR

in large, 40-column text, up at the top left of the screen, AND LOCKS up.
Great for real-time systems on Wall Street, huh?

Also, from what I've heard, Parity Errors on personal computer RAM chips
are EXTREMELY rare.  IBM's "solution" seems to just make the problem worse.

I'm no expert on the matter, so I may, of course, be wrong (and I KNOW
someone will tell me if I am...).  Maybe there's some system call to catch
it and stop if from crashing ... nahhh!  If that were the case, why didn't
they give you some way of recovering, in their own, elegant, MSDOS style? :-)

Memory Parity Error.  Abort, Retry, or Ignore?


There are some companies that offer error-checking and correction boards.
Of course, the problem here is that the main system memory will still be
just parity checked, without correction or recovery.

Of course, what's to stop people from making memory error checking /
recovery boards for the Amiga?  In fact, I remember seeing some advertised
awhile back.

>       On a related note, if this _is_ a problem, which RAM expansion
>cards come with parity chips?  I know the Starboard II has optional
>parity chips, but do any other manufacturers also have this?

Actually, I've heard the following opinion from someone:  Since the PC
has so many extra RAM chips for parity checking (12.5% extra), the extra
RAM chips INCREASE the possibility of parity errors, and, since not all
parity errors will be detected (what if 2 bits per [9-bit] byte change?
or any even number of bits?), the extra chips for parity detection aren't
worth it, and may even make the system less reliable.

>							-= Steve =-

"We may have come over here in different ships,
 but we're all in the same boat now."   --   Jesse Jackson

Rodney Ricks,   Atlanta University Center Computation Center
-- 
"We may have come over here in different ships,
 but we're all in the same boat now."   --   Jesse Jackson

Rodney Ricks,   Atlanta University Center Computation Center