10 CLEAR 200,&HF000:DEFUSR=&HF000
20 DATA 3E,00 :' LD  A,0
30 DATA D3,A0 :' OUT (A0h),A
40 DATA 3E,FE :' LD  A,FEh
50 DATA D3,A1 :' OUT (A1h),A
60 DATA C9    :' RET
70 DATA RET
80 READ Z$
90 IF Z$="RET" THEN 110
100 POKE &HF000+T,VAL("&h"+Z$):T=T+1:GOTO 80
110 A=USR(A)