On Thu, 29 Nov 2012 20:43:15 -0500, Gerhard Postpischil <[email protected]> 
wrote:
>I don't want to start an argument, but I have pet peeves with some of
>the design. For example, the TRAP instructions cause an exception unless
>trapping is properly enabled. Let's say I have a weird problem where a
>module is working fine in testing, but causes errors when placed in LPA.
>If I place TRAPs into the module, all other users will bomb. Had the
>design specified TRAPs to act as (expensive) NOPs, this would be a
>non-issue.

I can appreciate the issue, but in fairness to the architects, the usage notes 
indicate that TRAP was intended to be used to overlay the "real" instructions.  
I.e. not coded into the module.   That means whoever is overlaying the 
instructions must first properly enable traps.  From this I infer that they 
were actively discouraging programmers from leaving 'debug builds' in 
production code. 

But over the decades I, too, have encountered instructions whose behavior I 
found to be annoying or inconvenient.

Alan Altmark
IBM

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