[stella] Strange RIOT(?) register writes in Star Ship?!?

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

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