Subject: [stella] 6502 questions From: Ben Larson <wazzapfool@xxxxxxxxx> Date: Thu, 11 Oct 2001 08:24:45 -0700 (PDT) |
OK I am seriously confused as to the how the compare and branch instructions work. Ok first of all, correct me if I am wrong, but when you do a BPL doesn't that check to see if the value you are comparing is greater than the the value in the accumulator? Well if that's so, then is the processor comparing the two numbers as unsigned 8-bit integers or signed? In other words, what would be the outcome of, say...this: LDA #100 CMP #-20 ; -20 signed = 236 unsigned BPL AIsLess ; in a 2's comp. representation AIsNotLess . . . AIsLess Ben __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. http://personals.yahoo.com - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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