1000 REM SET UP THE SCREEN
 1010 X1=53600:REM X1=WAVES
 1020 FOR I1=X1 TO X1+31
 1030 POKE I1,128
 1040 NEXT I1
 1050 REM
 1100 REM SET UP THE BOAT
 1110 POKE X1,179:POKE X1+1,180
 1200 REM SET UP THE SUB
 1210 Y1=53810:REM Y1=SUB LOC
 1220 POKE Y1,7:POKE Y1+1,8
 1230 D=2
 1999 REM
 2000 REM MOVE AND FIRE SUB
 2010 Z2=57000:Y2=Y1:S1=0:S2=0
 2020 IFPEEK(Z2)=250THENY2=Y2-1
 2030 IFPEEK(Z2)=252THENY2=Y2+1
 2040 IFPEEK(Z2)=222THENY2=Y2-32
 2050 IFPEEK(Z2)=255THENY2=Y2+32
 2100 IFY2+1=Y1THENS2=PEEK(Y2):POKEY2,7:POKEY2+1,8:Z2=Y2+2:Y1=Y2:D=2
 2110 IFY2=Y1+1THENS2=PEEK(Y2):POKEY2,6:POKEY2-1,5:Z2=Y2-2:Y1=Y2:D=1
 2120 IFZ2<>57000THENPOKEZ2,32
 2130 IF Y2=Y1 GOTO 2400
 2200 REM SURFACE OR DIVE
 2210 IF D=1 THEN POKE Y1,32:POKE Y1-1,32
 2220 IF D=2 THEN POKE Y1,32:POKE Y1+1,32
 2230 IF D=1 THEN S1=PEEK(Y2):S2=PEEK(Y2-1)
 2240 IF D=2 THEN S1=PEEK(Y2):S2=PEEK(Y2+2)
 2250 IF D=1 THEN POKE Y2,6:POKE Y2-1,5
 2260 IF D=2 THEN POKE Y2,7:POKE Y2+1,8
 2270 GOTO 2400
 2400 REM FILL IN Z2 AREA
 2420 Y1=Y2
 2999 FOR I=1 TO 50:NEXT I:GOTO 2000