ADD LOGICAL and SUBTRACT LOGICAL were part of the original System/360, and are documented in the A22-6821-0 edition of the System/360 Principles of Operation, as well as in "Architecture of the IBM System/360", published in the IBM Journal in April, 1964, which describes the reasoning for many of the design choices.
-- Tom Marchant On Thu, 16 Jun 2022 14:36:12 +0000, Schmitt, Michael wrote: >My company's COBOL coding standards are* to define binary fields as signed >(e.g. PIC S9(4) BINARY). I'm wondering why that's the standard. > >The original standards were developed at least 40-60 years ago. They were >revised in 1994 but the signed binary guidance remained. > >One explanation could be if 50 years ago there were only signed binary >instructions such as ADD, but not logical instructions such as ADD LOGICAL. Or >maybe there were some logical instructions but not the full complement we have >today. > >Or it could be that whatever version of COBOL was used then (OS/VS COBOL or >earlier) was more efficient with signed binary, such as due to the choices it >made in instruction selection. > >So my question is, roughly when did the machines get unsigned binary >instructions for halfwords and fullwords?
