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From: seb1525@mvs.draper.COM ("Stephen E. Bacher")
Newsgroups: comp.lang.asm370
Subject: Re: New System/3x0 Instruction
Message-ID: <9103181737.AA01158@ucbvax.Berkeley.EDU>
Date: 18 Mar 91 13:19:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: IBM 370 Assembly Programming Discussion List
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Let's get away from philosophical arguments on what consistutes an
"instruction" and go back to the request that started this discussion.

Somebody wanted to submit a requirement to IBM to make a particular
function available at the machine level.  Whether this is implemented
in hardware, as microcode, or as an assist seems less important than
making the interface publicized and externalized so that assembler
programmers can safely use it without being restricted as to the
model of the machine they are on.  That is how the requirement
should be stated.

If implementing it as an OS assist, for example, would be unaccceptably
slow, the requirement should say something like "with the expected
performance improvement that is normally associated with System/3x0
machine-instruction-level operations".

As long as IBM publishes the description of the "instruction" in POP,
and doesn't restrict it to obscure models (like MVCIN), this should
satisfy the requirement.

 - SEB