From: "Farley, Peter x23353" <[email protected]>
To: <[email protected]>
Sent: Friday, June 17, 2022 12:55 AM
There were already logical instructions as early as the 360 machine series.
They were around even earlier: at least by 1951 such instructions existed.
However, early COBOL compilers (and even up to Enterprise V4) implemented the COBOL standard for
numeric values by converting unsigned binary values to packed decimal and zeroing out any integer
digits left of 4 digits for unsigned 9(4) COMP fields. That "COBOL standards enforcement" code
was slow because packed decimal instructions were significantly slower than binary ones on the
early machines.
On much more recent z hardware the vector packed decimal instructions
are significantly faster than the non-vector versions and newer compilers
are taking advantage of those instructions.
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