New subject: Searching for PickOs (early version), Oasis/Theos, UCSD Pascal and Prokey

4 Nov 2005

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Subject: Re: FPGA VAX update, now DIY TTL computers
   From: Paul Koning <pkoning at equallogic.com>
   Date: Fri, 04 Nov 2005 10:09:17 -0500
     To: cctalk at classiccmp.org

 >>>> "Kevin" == Kevin Handy
<kth at srv.net> writes: 
 Kevin> Allison wrote:
 > If you ask me the real horror of parity
memory is it only tells
> you disaster
> happend just as your about to crash.  ... 
 Kevin> Parity depends on if you would prefer a crash to silently
 Kevin> generating incorrect results.

 Kevin> ECC tries to hide the errors, but can still cause a crash if
 Kevin> too many bits change.

Correct.  And all error checking codes will fail to detect certain
errors.

Which is the right answer depends on what kind of errors you consider
likely enough to worry about, and what recovery you require.

       paul 
There is also the matter of fault tolerence.  Parity doen't provide that
unless the OS can map out the offending bank and the offending bank
isn't in a critical location.  ECC can keep you going if you have a 
stuck bit but it's up to the user/maintence to fix asap.

Allison