I'm pretty sure that given the context, the question is about AMODE 64 on z/Architecture.
To the original question: the sign is never "ignored". But there is no sign on base or index addresses. They are treated as unsigned numbers with the length of addresses of the current AMODE. When added up, along with displacement, any overflow is ignored, effectively making the result modulo-2**AMODE (I'm pretty sure that B. Dissen meant modulo 2**64). So, what you call -1 is actually 18,446,744,073,709,551,615, but because of overflow/wrap-around, it works like -1. For instructions with signed displacements, the displacement is sign-extended as needed; otherwise it's the same. sas On Sat, Oct 23, 2021 at 4:45 PM Mike Schwab <[email protected]> wrote: > On Sat, Oct 23, 2021 at 7:41 PM Paul Gilmartin > <[email protected]> wrote: > > > > On Sat, 23 Oct 2021 11:33:33 -0500, Joe Monk wrote: > > > > > >I know this will probably be an easy answer for somebody... but I dont > deal > > >with AM64 much. > > > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
