Subject: [stella] Strange RIOT(?) register writes in Star Ship?!? From: Manuel Polik <cybergoth@xxxxxxxx> Date: Thu, 29 Aug 2002 01:38:59 +0200 |
Hi there! While reverse-engineering Star Ship, I found two strange register writes, here they are, with my comments: 1: Startup of the console: LDA #$10 ; Useless port direction instructions... STA SWBCNT ; ...on the 2600 (?) 2: Routine handling Screensaver mode LDA gameOffBool ; A-> 00 v FF BNE SaverColorOk ; Game running? STA saverColor ; Y: Savercolor-> 0 SaverColorOk: EOR #$FF ; N: 2 Useless... STA SWCHB ; ...instructions(?) LDA SWCHB ; Check console switches AND #$08 ; Mask B/W-switch STA bwState ; bwState-> 08 v 00 TAY ; B/W mode on? BNE ColorMode ; N: Color mode LDA saverColor ; Y: B/W mode AND #$0F ; STA saverColor ; Saver colors -> B/W -> Any comments on my comments about the useless instructions appreciated :-) Greetings, Manuel ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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