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From: BRUCE@UMDD.BITNET (Bruce Crabill)
Newsgroups: comp.lang.asm370
Subject: Re: New System/3x0 Instruction
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Date: 18 Mar 91 12:34:09 GMT
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Reply-To: IBM 370 Assembly Programming Discussion List
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>Let's see now.  UPT and CFC are subroutines of SORT, not of the O.S.
>And they are now documented in the POP, which according to someone's
>recent definition makes them part of the architecture and real
>INSTRUCTIONS.

As much as I would like to say that they are microcode assists (and
really, they are), I would have to say that they are instructions for
the reasons noted.  The point is that once IBM as documented them in
the POP, they can't turn around in 6 months and change them to work
some other way.  With the OS type microcode assists, they can.  Nobody
says an instruction has to execute in a small number of micro
instructions.  Look at the VAX POP and their QUEUE and CRC instructions.
But I suspect that UPT and CFC are exceptions, rather than the rule
(probably ones that were forced on IBM because of legal reasons).
But I will agree with you that asking for changes to an existing POP isn't
likely to go far.  As an RPQ type deal maybe.

                                       Bruce