The program:

DATA aries,taurus,gemini,cancer,leo,virgo,libra,scorpio,sagittarius,capricorn,aquarius,pisces,"unknown to this astrologer."

DIM sign$(13)

MAT READ sign$

INPUT prompt "What is your birthday? (MM-DD,eg.1-9 for Jan. 9) ":reply$

CALL month (m,reply$)

CALL day (d,reply$)

CALL astrologer(d,m,i)

SET COLOR "red"

PRINT "Your sign is ";sign$(i)

SET COLOR "green"

PRINT "Cross my palm with silver for your horoscope."

END

SUB month (m,a$)

LET b$=a$[1:pos(a$,"-")-1]

LET m=val(b$)

END SUB

SUB day (d,c$)

LET d$=c$[posr(c$,"-")+1:len(c$)]

LET d=val(d$)

END SUB

SUB astrologer (d,m,i)

IF (d>=23 and m=9) or (d<=22 and m=10) then

LET i=7

ELSEIF (d>=22 and m=11) or (d<=21 and m=12) then

LET i=9

ELSEIF (d>=21 and m=3) or (d<=19 and m=4) then

LET i=1

ELSEIF (d>=20 and m=4) or (d<=20 and m=5) then

LET i=2

ELSEIF (d>=21 and m=5) or (d<=21 and m=6) then

LET i=3

ELSEIF (d>=22 and m=6) or (d<=22 and m=7) then

LET i=4

ELSEIF (d>=23 and m=7) or (d<=22 and m=8) then

LET i=5

ELSEIF (d>=23 and m=8) or (d<=22 and m=9) then

LET i=6

ELSEIF (d>=24 and m=10) or (d<=21 and m=11) then

LET i=8

ELSEIF (d>=22 and m=12) or (d<=19 and m=1) then

LET i=10

ELSE

LET i=13

SET COLOR "brown"

PRINT "You cannot be guided by local stars. "

END IF

END SUB

The output for reply$ 9-26:

Your sign is libra

The output for reply$ 12-12:

Your sign is sagittarius

The output for any other birthday:

You cannot be guided by local stars

Your sign is unknown to this astrologer