IMHO, the next instruction to add to z/Architecture would be an instruction to
clear storage to zeros.
Right now a number of methods are in widespread use, none of which are clean
and simple. I mean, it’s been almost sixty years.
MVCL takes three registers to set up beforehand; XC sets the condition code and
is not variable length, and the overlapping MVC is a kluge and not variable
length either. An EX instruction is also a kluge.
All you need is the address and length to accomplish this, preferably in two
versions, one with an immediate operand for the length and another which uses,
for example, a register, perhaps register zero. A long displacement would be a
plus.
To avoid issues with interruptibility, the length would need to be limited to
256 bytes. I don’t think the length restriction would be an issue in most
cases.
Such an instruction might look like this:
CLEAR FieldA
Or
LLGF R0,Varlen
CLEARR
Similar instructions for compare logical and move would be nice as well.
Tom Harper
Phoenix Software International
Sent from my iPhone
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