Sorry for the confusion but that's not the question that I was asking. I agree 
with you on guaranteeing the consistency using the count.

I'm talking about TCB1 using PLO CSDST to store 2 adjacent words (4th & 6th PLO 
operands) and TCB2 using LM or LG for those same 2 words. There is a very small 
window between the 2 store's where TCB2 will pick up inconsistent inconsistent 
values. In other words, the first store has completed and the LM/LG occurs 
before the second store completes. This window is extremely small because PLO 
cannot be interrupted and the instruction was prepared before performing the 
stores. 

I think the window is so small that even under heavy usage, you would only see 
an error every couple of months but it does exist. I think TCB2 must also use 
the PLO compare and load to avoid this situation.

Thanks for the great information, Jon Perryman.

From: Kenneth Wilkerson <[email protected]>
>
>
>The order of stores is unpredictable except that  according to the POM,
>operand 2 (in this case, the count) is always stored last. 
>

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