10 DIM o$(5)
20 LET xm=0: LET xx=31: REM screen limits
30 LET ym=0: LET yx=18
40 LET xo=16: LET yo=9: REM origin
50 LET xc=xo: LET yc=yo
60 PRINT AT yc,xc;" ": REM entry point for scan loop - blank cursor
70 LET xc=xo: LET yc=yo
80 LET t=IN 31
90 IF t=1 OR t=5 OR t=9 OR t=17 OR t=21 OR t=25 THEN LET xc=xx: LET o$(2)="R": REM right
100 IF t=2 OR t=6 OR t=10 OR t=18 OR t=22 OR t=26 THEN LET xc=xm: LET o$(1)="L": REM left
110 IF t=4 OR t=5 OR t=6 OR t=20 OR t=21 OR t=22 THEN LET yc=yx: LET o$(4)="D": REM down
120 IF t=8 OR t=9 OR t=10 OR t=24 OR t=25 OR t=26 THEN LET yc=ym: LET o$(3)="U": REM up
130 IF t>=16 THEN LET o$(5)="F": REM fire
140 PRINT AT 21,0;"Input:";o$
150 PRINT AT yc,xc;"+"
160 LET o$="     ": REM five spaces to blank output line again
170 GO TO 60