分析下列程序: DATA SEGMENT DISPDATA DB'INPUT NUMBER KEY,CR OR SP RETURN',0DH,0AH DATA ENDS CODE SEGMENT ASSUME CS:CODE,DS:DATA START: MOV AX,DATA MOV DS,AX LEA DX,DISPDATA ; (1) MOV AH,09H ; (2) INT 21H AGAIN: MOV AH,01H ; (3) INT 21H CMP AL,0DH ; (4) JZ EXIT ; (5) CMPAL,20H ; (6) JZ EXIT ; CMP AL,30H ; (7) JBE AGAIN ; (8) CMP AL,39H ; (9) JAAGAIN ; (10) SUB AL,30H ; (11) MOV CL,AL ; (12) AND CX,0FFH DONE: MOV AH,02H MOV DL,07H ; (13) INT 21H CALL DELAY ; LOOP DONE JMP AGAIN EXIT: MOV AH,4cH ; (14) INT 21H DELAY: PUSH CX MOV CX,0FFFH LOOP DELAY POP CX RET CODE ENDS END START 按照语句中;号后面的题号(1)~(14),试分别回答这些语句的功能。程序执行后将完成什么功能?