Detect broken VBL on Mac IIe card (#508)

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Tom Greene 2022-10-08 19:55:28 -04:00 committed by GitHub
parent 7bda61382b
commit adf3d10db0
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@ -22,7 +22,7 @@ BuildVBLFunction
beq @build_iic ; //c family
lda romid_mac
cmp #ROMID_IIECARD
beq @build_none ; broken in some versions, disable
beq @build_iiecard ; Mac Apple IIe card
sec
jsr idroutine ; check for IIgs
bcs @NotGS
@ -45,6 +45,21 @@ BuildVBLFunction
lda #$4C
sta UnwaitForVBL
rts
@build_iiecard
lda $FBBE ; check IIe card software version because v2.2.2d1 is broken
cmp #$03 ; $03 = v2.2.x
bne @NotGS ; all other versions are ok
ldy #$08 ; Found v2.2.x but don't know which one, so test if VBL works
ldx #$00
- bit $C019
bmi @NotGS
dex
bne -
dey ; keep checking for ~22,000 cycles (a little over 1/50 of a second)
bne - ; if no VBL by then fall through to @build_none
@build_none
lda #$60
sta WaitForVBL