User talk:Tcb

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what is IEF in IEFBR14?

I don't know what is it. -- Sergey Tyurin 06:38, 1 November 2006 (UTC)

The first three letters of IBM software and error messages, of the vintage concerning IEFBR14, referred to the component of the operating system involved. IEF was the main scheduler, while, for example, IEY was a FORTRAN compiler.

IEFBR14 was originally a no-op program that, on entry, did a Branch Register (BR) to the address in Register 14, which, by convention, had the return address from a subroutine call. The original one-instruction program had one bug: the subroutine call conventions required putting a completion code in Register 15, which should be zero for normal completion. IEFBR14 had to be modified to do a Subtract Register 15 from itself, zeroing it, before doing a BR14. Howard C. Berkowitz (talk) 14:15, 14 December 2007 (UTC)