From: "Paul Gilmartin" <[email protected]>
Sent: Friday, October 16, 2015 12:25 PM
On 2015-10-15 15:26, Tony Harminc wrote:
I recall struggling to backport some code
which used IPM...SPM to older hardware that lacked those instructions.
Must've been *very* old hardware... SPM is original with S/360. IPM is
much later (XA, iirc, because of issues with BALR and the high byte in
31-bit mode). Before that BALR was the standard way to capture the CC
in a register.
Yup. That old. (Just like me.)
Compatibility bind. Couldn't use IPM on 370; BALR didn't capture
CC in AMODE 31. Had to tread lightly and not stomp on CC. I suppose
I could have used BALR ,0 and tested bit 0: if 0, CC is captured;
if 1, I could use IPM. Oops. Can't test bit 0 without altering CC.
I recall a machine having a "logicize" instruction, producing either
1 or zero according to the outcome of any arithmetic operation.
(Might have been a Burroughs machine?).
That would have been very useful on S/360 and later ...
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