>Yes, set the SAC bits first, otherwise the access register is set with
zeros.
But if you set the ASC bits to something not 00 and not 01 ("SAC"
instruction sets "ASC bits"), the LAE instruction will neither set to 0
nor copy the AR but will do what it is defined to do.
>LAE R3,(R4) - loads the value from the location pointed to by R4 in the
>home address space into R3 and sets the AR3 register with 0, regardless
of
>the SAC values at the time.
This is not correct (since that's equivalent to LAE R3,4). And even if
it did not refer to loading a value (which LAE of course doesn't do) it
still wouldn't be correct if the instruction were LAE R3,0(R4) or LAE
R3,0(R4,0).
The AR is set to 0 only in Primary ASC mode cases.
The relevant section of the principles of operation was posted in earlier
replies and clearly describes the behavior for each of the 4 ASC modes.
I don't know why the OP had difficulty finding that information.
Peter Relson
z/OS Core Technology Design
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