
 1000         .MA VECTOR
 1010         JSR $FF58
 1020  :1     TSX
 1030         LDY $100,X
 1040         DEX
 1050         LDA $100,X
 1060         CLC
 1070         ADC #:3-:1+1
 1080         BCC :2
 1090         INY
 1100  :2     .DO ']1='Y   CTRL-Y?
 1110         STA $3F9
 1120         STY $3FA
 1130         LDA #$4C
 1140         STA $3F8
 1150         .ELSE        OR &?
 1160         STA $3F6
 1170         STY $3F7
 1180         LDA #$4C
 1190         STA $3F5
 1200         .FIN
 1210         RTS
 1220  :3
 1230         .EM

