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From: A01MES1@NIU.BITNET (Michael Stack)
Newsgroups: comp.lang.asm370
Subject: Re: OPSYN opcode in ibm bal
Message-ID: <8906102108.AA12554@jade.berkeley.edu>
Date: 9 Jun 89 19:29:00 GMT
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Reply-To: IBM 370 Assembly Programming Discussion List <ASM370%UCF1VM.bitnet@jade.berkeley.edu>
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> The uses for OPSYN are pretty hard to come by.  ...

Bruce Uttley of U of Waterloo can probably give a good history of
OPSYN, but my recollection is that problems arose when using the
extended Branch Conditional Register mnemonics which were not
available in early assemblers.  Users would then write macros for
instructions like BNER (easier to recall than BCR 7,), only to
have those collide with those codes as instructions in newer versions
of the assembler (I recall that Waterloo's ASMG had this as an
option).  By including   BNER  OPSYN  , before the BNER macro, it
was possible to assemble without errors, even if the extended
mnemonics were available.  Unfortunately, both ASM (F) and the manual
which described it are long gone, and I can't prove that this worked,
but that is what I recall.  Bruce, are you listening...?

Michael Stack
Northern Illinois University