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From: dandrews@bilver.UUCP (Dave Andrews)
Newsgroups: comp.lang.asm370
Subject: Re: Bogon interrupts...
Message-ID: <9105280604.AA09742@ucbvax.Berkeley.EDU>
Date: 27 May 91 17:57:05 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: IBM 370 Assembly Programming Discussion List
              <ASM370@OHSTVMA.BITNET>
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In article <9105262118.AA28795@ucbvax.Berkeley.EDU> IBM 370 Assembly
        Programming Discussion List <ASM370@OHSTVMA.BITNET> writes:
>Hmmm... And I thought that the 360/91 was the only machine that had
>those blasted imprecise interrupts.  NOPR 0 was a special
>implementation that flushed the pipeline, so that you could isolate
>instructions that were causing S0C0s.
>
>/Leonard
>So I'm not the only who keeps some old manuals for their historical
>value.  I wonder where my 360/20 F.C. is...

I was also a little surprised about the m65.  In my old PLIF Programmer's
Reference (there are more of us pack rats than you'd think!) I remember
the section on the M91 option, where the F compiler would insert NOPs
at strategic places in order to handle ON-units properly.

From Appendix G:
  "IBM System/360 Models 91 and 195 are high-speed processing systems
  in which more than one instruction is executed concurrently.  As a
  result, an exception may be detected and an interrupt occur when
  the address of the instruction which caused the exception is no longer
  held in the central processing unit.  Consequently, the instruction
  causing the interrupt cannot be precisely identified.  Interrupts of
  this type are termed _imprecise_."
It goes on to describe the M91 option.  They say:
  "The option must always apply when the compiler is used to produce
  object programs for execution on a Model 91 or 195.  The effect of
  the option is:
    1.  To cause the compiler to insert 'no-operation' instructions
        at certain points in the program to localize imprecise interrupts...
        No-operation instructions are generated a. before an ON statement
        b. before a REVERT statement, c. before compiled code to set the
        SIZE condition, d. before compiled code to change prefix conditions,
        e. for a null statement, and f. before every statement if the
        STMT compiler option applies.
    2.  To creat an ESD entry for the PL/I library module IHEM91..."

Anyway, it doesn't mention m65.  Doesn't mean you aren't right, though.
I've Been Misled, and all that.

- Dave