Before the advent of the COMPARE AND TRAP type instructions, we all use to use EX Rnn,* to force a S0C3 abend for "this should never happen" conditions. But with baseless code, if you change EX Rnn,* to EXRL Rnn,* then you may not get your expected S0C3 when Rnn is a register other than zero. The low order nybble of the second byte of EXRL is zero indicating an EXRL instruction, if you modify it then it becomes some other X'C0' instruction!
Robert Ngan DXC Luxoft -----Original Message----- From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf Of Charles Mills Sent: Friday, February 11, 2022 17:27 To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Executing a ZAP Instruction Meaning what? You can't EX a PACK instruction? Are you absolutely certain of that? I think you can EX anything except an EX/EXR. Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Tom Marchant Sent: Friday, February 11, 2022 3:00 PM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Executing a ZAP Instruction On Fri, 11 Feb 2022 17:03:09 -0500, Dave Clark <dlcl...@winsupplyinc.com> wrote: > Does that mean ZAP can't be EXecuted? Yes, you can EXecute a ZAP instruction. But, you can't use it to PACK -- Tom Marchant
