adjuster startup once again - not the most effective way, but should be more compatible with cartridges
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@@ -34,32 +34,7 @@ ioinit:
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cpy #$80 ; $20 * amount of chips to silence, $80 to silence 4 chips
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bne -
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;; Detect video system (PAL/NTSC), use Graham's method, as it's short and reliable
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;; see here: https://codebase64.org/doku.php?id=base:detect_pal_ntsc
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ioinit_w0:
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lda VIC_RASTER
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ioinit_w1:
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cmp VIC_RASTER
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beq ioinit_w1
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bmi ioinit_w0
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;; Result in A, if no interrupt happened during the test:
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;; #$37 -> 312 rasterlines, PAL, VIC 6569
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;; #$06 -> 263 rasterlines, NTSC, VIC 6567R8
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;; #$05 -> 262 rasterlines, NTSC, VIC 6567R56A
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cmp #$07
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bcs ioinit_pal
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ioinit_ntsc:
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lda #$00
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beq +
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ioinit_pal:
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lda #$01
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*
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sta PALNTSC
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;; XXX: calibrate TOD for both CIA's, see here: https://codebase64.org/doku.php?id=base:efficient_tod_initialisation
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@@ -81,17 +56,6 @@ ioinit_pal:
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ldy #<16421
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ldx #>16421
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lda PALNTSC
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bne +
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;; NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
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;; is clocked at 1.022727 MHz, so that 1/60s is 17045 CPU cycles
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ldy #<17045
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ldx #>17045
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;; Store the IRQ timing constant to CIA chip
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*
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sty CIA1_TIMALO
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stx CIA1_TIMAHI
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