Subject: [stella] chewing a unicycle From: "Andrew Davie" <adavie@xxxxxxxxxxxxx> Date: Wed, 14 Feb 2001 00:29:36 +1100 |
Found myself needing to use up a single cycle. For eg: in the following code, I have 4 cycles used. nop ;2 nop ;2 If I was in tightly timed code, and wanted to do a store at that point, like this... sta COLUBK ;3 ;one cycle extra needed to be used... how? I've only used 3 cycles, which will stuff the timing of the code. I need to use another cycle. The solution is to change the instruction you inserted, or one earlier, to long addressing instead of zero page addressing. I'm not sure how to do that with DASM, but I simply looked up the opcode for the long instruction and did it manually, like this.... .byte $8D,COLUBK,0 This is effectively replacing the zero-page address refrence (3 cycles) with an absolute address (4 cycles). Thought this might help somebody, sometime :) Cheers A -- _ _ _| _ _ _| _ * _ _ , (_|| )(_|( (/_\/\/ (_|(_|\/(_(/_ ,~' L_|\ ,-' \ see my Museum of Soviet Calculators at ( \ http://www.taswegian.com/MOSCOW/soviet.html \ __ / L,~' "\__/ @--> v - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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