Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!cs.utexas.edu!usc!apple!marc
From: marc@Apple.COM (Mark Dawson)
Newsgroups: comp.sys.mac.hardware
Subject: Re: IIci Parity Detection (Was: Re: 4Mb SIMMs)
Message-ID: <38500@apple.Apple.COM>
Date: 9 Feb 90 21:09:50 GMT
References: <17118@eerie.acsu.Buffalo.EDU> <6530@uhccux.uhcc.hawaii.edu> <1120@gort.cs.utexas.edu>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 30

In article <1120@gort.cs.utexas.edu> jason@cs.utexas.edu (Jason Martin Levitt) writes:
>In article <6530@uhccux.uhcc.hawaii.edu> yuan@uhccux.uhcc.hawaii.edu (Yuan 'Hacker' Chang) writes:
>>
>>	FYI -- The IIci (not the IIcx) will do parity detection when fed 
>>x9 SIMMs.  That's the good news.  The bad news is that all it does with
>>that information is to ask you to restart (according to the manual).  I'd
>>much prefer to be given a chance to recover from the error.  If I'm working
>>on a 2M document on a 32M machine, I wouldn't want a flipped bit where it
>>doesn't count to cause me to loose my work.  I think we'll stick with x8
>>SIMMs...
>
>  I thought that you had to order parity checking as an "optional
>feature" [quote from IIci Owner's Manual] and that it did not come standard
>with parity checking ability. Does the IIci automatically do parity
>checking when 1x9 SIMMs are used? 
>
>   ---Jason
>-----

You do need to order a IIci with parity.  In this case, if you DON'T have
parity SIMMs installed, everytime you boot, you'll get a message telling
you that no parity was detected (it assumes that if you have a parity machine,
you'll be using parity SIMMs). 

Also note that ALL of the SIMMs need to be parity, or the IIci will turn off
parity--thus having 1mb parity SIMMs in bank A and non-parity SIMMs in bank B 
will cause the IIci to assume there's no parity installed (i.e. you've just 
wasted the extra cost of the parity SIMMs).

   Mark