10 CLEAR 200,&HD000:DEFUSR=&HD000
20 DATA 3E,C3         :'LD  A,C3h
30 DATA 01,10,D0      :'LD  BC,D010h
40 DATA 02            :'LD  (BC),A
50 DATA C9,"RET"      :'RET
70 READ A$:IF A$="RET" THEN 110
90 POKE &HD000+T,VAL("&h"+A$):T=T+1:GOTO 70
110 A=USR(A)
120 PRINT "A=";HEX$(PEEK(&HD010))