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base:the_double_irq_method

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base:the_double_irq_method [2016-11-05 21:10]
monte_carlos [Theory]
base:the_double_irq_method [2016-11-05 21:12] (current)
monte_carlos [Theory]
Line 70: Line 70:
 fixcycle bit $d020 fixcycle bit $d020
 ... ...
 +
 </​code>​ </​code>​
  
 +The corresponding irq init looks like this:
 +
 +<​code>​
 +.PROC irqInit
 + lda #$7f
 + sta $dc0d
 + bit $dc0d
 + lda #$81
 + sta $d01a
 + lda #<irq0
 + sta $0314
 + lda #>irq0
 + sta $0315
 + lda #<irq
 + sta $fffe
 + lda #>irq
 + sta $ffff
 + lda #$38
 + sta $d012
 + lda #$36
 + sta $01
 + lsr $d019
 + rts
 +.ENDPROC
 +
 +The lsr $d019 at the end of the init is performed to clear the irq request if for some reason a rasterirq request is rised during init.
 +
 +</​code>​
base/the_double_irq_method.txt ยท Last modified: 2016-11-05 21:12 by monte_carlos