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From: scw@ucla-cs.UUCP
Newsgroups: net.followup
Subject: Re: Unix, Unixpeople, Usenix (really IBM Utilities)
Message-ID: <7524@ucla-cs.ARPA>
Date: Sun, 10-Nov-85 11:10:47 EST
Article-I.D.: ucla-cs.7524
Posted: Sun Nov 10 11:10:47 1985
Date-Received: Wed, 13-Nov-85 03:28:22 EST
References: <96@tekadg.UUCP> <9700101@uiucdcs> <150@mit-eddie.UUCP> <256@ivax.icdoc.UUCP> <2168@amdahl.UUCP>
Reply-To: scw@ucla-cs.UUCP (Stephen C. Woods)
Organization: UCLA Computer Science Department
Lines: 41

In article <2168@amdahl.UUCP> canopus@amdahl.UUCP (Alpha Carinae) writes:
>> 
>> In article <150@mit-eddie.UUCP> gds@mit-eddie.UUCP (Greg Skinner) writes:
>> >Unix may have[...]manual ? It lists them in order.
>
>  IEFBR14 is not a system message; it is a dummy utility which does a
>  branch on register 14 (essentially exits once it is called).  I would
>  have suggested the OS Utilities manual, but it doesn't seem to be in
>  there, either!

Interestingly enough IEFBR14 had a bug in the first release.  System
360 (now called 370) had a calling sequence as follows:
(1) R15 -> entry
(2) R14 -> return
(3) [all kinds of stuff about save areas]
    and a return sequence as follows
(1) restore all registers (except R0-R1 which may contain function return
    values)
(2) Put the condition code (a number indicating the severity of any errors
    that occured durring execution 0=none, 2= very minor, 4=warning,
    ... 32 terminal errors (hardware failures etc).
    then 
    br	14		branch to where r14 points

The problem with IEFBR14 was that it didn't clear R15 before it returned

	bad			good
	BR	14		XR	15,15
				BR	14

>
>  Let's face it.  All operating systems have their warts.  The original
>  article (which I thought quite humorous) could be written about *any*
>  operating system (I've got quite a collection of OS stuff!)

Ain't it the truth, event the most trivial of operating systems have
little warts, knobs and bumps sticking out of their 'black boxes'
to trip, bump, mangle and otherwise injure our collective egos.
>-- 
>Frank Dibbell     (408-746-6493)     ...!{ihnp4,cbosgd,sun}!amdahl!canopus
>Amdahl Corporation, Sunnyvale CA     [This is the obligatory disclaimer..]