MESSAGE
DATE | 2014-12-09 |
FROM | Ruben Safir
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SUBJECT | Subject: [LIU Comp Sci] Relative - PC addressing
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From owner-learn-outgoing-at-mrbrklyn.com Tue Dec 9 02:39:54 2014 Return-Path: X-Original-To: archive-at-mrbrklyn.com Delivered-To: archive-at-mrbrklyn.com Received: by mrbrklyn.com (Postfix) id A45E2161131; Tue, 9 Dec 2014 02:39:54 -0500 (EST) Delivered-To: learn-outgoing-at-mrbrklyn.com Received: by mrbrklyn.com (Postfix, from userid 28) id 8568E161157; Tue, 9 Dec 2014 02:39:54 -0500 (EST) Delivered-To: learn-at-nylxs.com Received: from mailbackend.panix.com (mailbackend.panix.com [166.84.1.89]) by mrbrklyn.com (Postfix) with ESMTP id AB247161131 for ; Tue, 9 Dec 2014 02:39:53 -0500 (EST) Received: from panix2.panix.com (panix2.panix.com [166.84.1.2]) by mailbackend.panix.com (Postfix) with ESMTP id 4B16F14FB1; Tue, 9 Dec 2014 02:39:52 -0500 (EST) Received: by panix2.panix.com (Postfix, from userid 20529) id 2527B33C69; Tue, 9 Dec 2014 02:39:52 -0500 (EST) Date: Tue, 9 Dec 2014 02:39:52 -0500 From: Ruben Safir To: Samir Iabbassen Cc: learn-at-nylxs.com Subject: [LIU Comp Sci] Relative - PC addressing Message-ID: <20141209073952.GA2836-at-panix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: owner-learn-at-mrbrklyn.com Precedence: bulk Reply-To: learn-at-mrbrklyn.com
7131 Relative Addressing or PC-Relative Addressing 311 Implicitly referenced register is a program counter 312 added to the Address field of the Instruct to form an EA 313 Address field is normally a two complement number for this purpose 314 Thus, the effective address is a displacement relative to the address of the instruction.
I just don't get how this plays out ina fetch cycle. The PC is read and it pulls an instruction from that value in the PC, unless this is a form of an indirect memory addrssing, scheme where the PC is read, the insturction is read, then the A value in the instruction is added to the PC and then an operand is swept in from that offset location. So then the optcode from the instruction pulling in (PC) + A
help
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