> Nope, it was the use of a X'80' in the high-order byte of a fullword to >
> terminate a variable-length parameter list (of fullwords).
Isn't that the "existing exploitation of the sign bit"
that Gil is alluding to?
> Date: Mon, 20 Oct 2008 20:31:08 -0500
> From: [EMAIL PROTECTED]
> Subject: Re: Addressing Scheme with 64 vs 63 bits
> To: IBM-MAIN@BAMA.UA.EDU
>
> On Mon, 20 Oct 2008 15:00:48 -0500, Paul Gilmartin
> <[EMAIL PROTECTED]> wrote:
>
> >I thought 31-bit was for compatibility with existing exploitation
> >of the sign bit; but there was no legacy convention of using
> >the sign bit of shorter addresses stored in a doubleword to
> >preserve compatibility with.
> >
>
> Nope, it was the use of a X'80' in the high-order byte of a fullword to
> terminate a variable-length parameter list (of fullwords).
>
> And, FWIW, the S360/67 did implement (as an option) 32-bit addressing...
> Really caused problems when some customers had to get off of TSS and try to
> stuff things in 31-bit.
>
> W. Kevin Kelley IBM POK Lab -- z/OS Core Technical Development
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