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Detect broken VBL on Mac IIe card (#508)
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@ -22,7 +22,7 @@ BuildVBLFunction
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beq @build_iic ; //c family
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lda romid_mac
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cmp #ROMID_IIECARD
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beq @build_none ; broken in some versions, disable
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beq @build_iiecard ; Mac Apple IIe card
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sec
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jsr idroutine ; check for IIgs
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bcs @NotGS
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@ -45,6 +45,21 @@ BuildVBLFunction
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lda #$4C
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sta UnwaitForVBL
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rts
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@build_iiecard
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lda $FBBE ; check IIe card software version because v2.2.2d1 is broken
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cmp #$03 ; $03 = v2.2.x
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bne @NotGS ; all other versions are ok
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ldy #$08 ; Found v2.2.x but don't know which one, so test if VBL works
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ldx #$00
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- bit $C019
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bmi @NotGS
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dex
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bne -
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dey ; keep checking for ~22,000 cycles (a little over 1/50 of a second)
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bne - ; if no VBL by then fall through to @build_none
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@build_none
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lda #$60
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sta WaitForVBL
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