2. LOW F1
IF C1=0 THEN X=1 : GOSUB AR: RETURN
IF C2=0 THEN x=2 : GOSUB AR : RETURN
IF C3=0 THEN X=3 : GOSUB AR: RETURN
IF C4=0 THEN X=”A”: GOSUB AR: RETURN
HIGH F1
LOW F2
IF C1=0 THEN X=4: GOSUB AR : RETURN
IF C2=0 THEN x=5: GOSUB AR : RETURN
IF C3=0 THEN X=6: GOSUB AR : RETURN
IF C4=0 THEN X=”B”: GOSUB AR : RETURN
HIGH F2
LOW F3
IF C1=0 THEN X=7: GOSUB AR : RETURN
IF C2=0 THEN x=8: GOSUB AR : RETURN
IF C3=0 THEN X=9: GOSUB AR : RETURN
IF C4=0 THEN X=”C”: GOSUB AR : RETURN
HIGH F3
LOW F4
IF C1=0 THEN X=”*” : GOSUB AR : RETURN
IF C2=0 THEN x=0: GOSUB AR : RETURN
IF C3=0 THEN X=”#”: GOSUB AR: RETURN
IF C4=0 THEN X=”D”: GOSUB AR : RETURN
HIGH F4
PAUSE 10
GOTO TECLADO
AR :
IF C1=0 THEN GOTO AR
IF C2=0 THEN GOTO AR
IF C3=0 THEN GOTO AR
IF C4=0 THEN GOTO AR
RETURN
END