; 实验三-5：字符分类程序
; 功能：判断大写/小写字母或其他字符
; 结果：1=大写字母，2=小写字母，3=其他字符

DATA SEGMENT
    CH DB 'A'
    RESULT DB ?
DATA ENDS

CODE SEGMENT
    ASSUME CS:CODE, DS:DATA
START:
    MOV AX, DATA
    MOV DS, AX
    MOV AL, CH
    CMP AL, 'A'
    JNB NL_CHECK
    JMP OTHER
NL_CHECK:
    CMP AL, 'Z'
    JNA UPLETTER
    CMP AL, 'a'
    JNB LL_CHECK
    JMP OTHER
LL_CHECK:
    CMP AL, 'z'
    JNA LOWLETTER
    JMP OTHER
UPLETTER:
    MOV RESULT, 1      ;大写字母
    JMP EXIT
LOWLETTER:
    MOV RESULT, 2      ;小写字母
    JMP EXIT
OTHER:
    MOV RESULT, 3      ;其他字符
EXIT:
    MOV AH, 4CH
    INT 21H
CODE ENDS
END START