Many logical instructions -- fullword and character anyway -- go back to the very first System 360's.
I've got a System 370 Yellow Card here and it includes AL, ALR, CL, CLR, SL and SLR as System 360 instructions. Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Schmitt, Michael Sent: Thursday, June 16, 2022 7:36 AM To: [email protected] Subject: When did logical instructions appear? 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? * "are" isn't the right word here, since the COBOL coding conventions are no longer published anywhere. I only know what they are because I was on the team that reviewed the 1994 revision, and have a copy saved.
