Defence Force Wiki

Example code by Fabrice Broche:

_Synchro
.(
STA $04     
STX $03     
LDA #$80    
STA $00     
LDA #$BB    
STA $01     
LDY #$00    
CLC         
L1
LDA $04     
STA ($00),Y 
LDX $03      
loop1
DEX         
BNE loop1   
TYA         
ADC #$28    
TAY         
BCC L1   
LDA #$00    
ADC $01     
STA $01     
CMP #$C0    
BCC L1  
RTS        
.)

_DoSync
.(
SEI         
L6
LSR $02DF   
LDA #$40    
L2
BIT $030D   
BEQ L2   
LDA #$11    
LDX #$01    
JSR _Synchro   
LDA #$12    
LDX #$12    
JSR _Synchro   
BRK         
BRK         
LDA $02DF   
CMP #$D3    
BNE L3   
INC $0306   
BNE L3   
INC $0307   
L3
CMP #$C6    
BNE L4   
LDX $0306   
BNE L5   
DEC $0307   
L5
DEC $0306   
L4
CMP #$D1    
BNE L6   
CLI         
RTS         
.)

Double buffered smooth sinus Dots