
 1000  *SAVE S.STRING.ADD
 1010  *--------------------------------
 1020  *      STRING ADDITION
 1030  *--------------------------------
 1040  S1     .AS /000189/
 1050  S2     .AS /007030/
 1060  *--------------------------------
 1070  S3     .AS /      /
 1080  *--------------------------------
 1090  ADD    LDX #5       6 DIGITS
 1100         CLC          START WITH NO CARRY
 1110  .1     LDA S1,X     NEXT DIGIT PAIR
 1120         AND #$0F     CHANGE ASCII TO BINARY CODE
 1130         ADC S2,X     RESULT IS IN ASCII AGAIN
 1140         CMP #$3A     UNLESS MORE THAN 9
 1150         BCC .2       OKAY
 1160         SBC #10      NEED TO PROPAGATE CARRY
 1170  .2     STA S3,X     SUM DIGIT IN ASCII
 1180         DEX          MORE DIGITS?
 1190         BPL .1       YES
 1200         RTS          NO, RETURN

