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From: VALDIS@VTVM1.CC.VT.EDU (Valdis Kletnieks)
Newsgroups: comp.lang.asm370
Subject: Re: SAVE area offset zero
Message-ID: <9008210738.AA12405@ucbvax.Berkeley.EDU>
Date: 21 Aug 90 07:32:35 GMT
References: <TROTH%RICEVM1.RICE.EDU@OHSTVMA.IRCC.OHIO-STATE.EDU>
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On Mon, 20 Aug 90 19:52:36 CDT Rick Troth said:
>        So what does offset zero refer to?  If you say "R13 goes there",
>I won't shoot you.  Pointing to itself would provide validity checking,
>but is that what offset zero does?  If not,  then what?

Offset 0 is used by the PL/I compiler (At least at the F level, I'd have to
read up on what the Optimizing and Version 2 compilers do).  It uses this
area as a pointer to the 'pseudo-register' area.  Since it's 3:30AM, I'll
avoid trying to explain pseudo-registers - the PL/I Programmer's Guide does
it better than I could hope to at this time of night....

Disclaimer: My last serious PL/I work was on a 360/65 running OS/MVT.. ;-)

                                      Valdis Kletnieks
                                      Computer Systems Engineer
                                      Virginia Tech