设计一个基于51单片机的秒表计时器，计时时间显示格式：hh.mm.ss.SS，计时器有两个按钮：启动/停止按钮、复位按钮。计时器有两种工作状态：停止状态、计时状态，汇编语言代码

好的，以下是一个基于51单片机的秒表计时器的汇编语言代码，计时时间显示格式为hh.mm.ss.SS，计时器具有两个按钮：启动/停止按钮和复位按钮，计时器有两种工作状态：停止状态和计时状态。这个代码使用定时器0来计时，使用LCD模块来显示计时时间。

ORG 00H
    LJMP MAIN

ORG 020H
    MOV TH0, #4CH
    MOV TL0, #00H
    INC MS
    JZ SEC_INC
    JMP EXIT

SEC_INC:
    CLR MS
    INC SEC
    JZ MIN_INC
    JMP EXIT

MIN_INC:
    CLR SEC
    INC MIN
    JZ HOUR_INC
    JMP EXIT

HOUR_INC:
    CLR MIN
    INC HOUR
    JMP EXIT

EXIT:
    RETI

MAIN:
    MOV SP, #7FH
    MOV TMOD, #01H
    MOV IE, #82H
    MOV PCON, #00H
    MOV A, #38H
    ACALL LCD_INIT
    MOV A, #01H
    ACALL LCD_CMD
    MOV A, #06H
    ACALL LCD_CMD
    MOV A, #0CH
    ACALL LCD_CMD
    MOV A, #80H
    ACALL LCD_CMD
    MOV A, #0FH
    ACALL LCD_CMD
    MOV HOUR, #00H
    MOV MIN, #00H
    MOV SEC, #00H
    MOV MS, #00H
    MOV STATE, #00H
    MOV START_FLAG, #00H
    MOV STOP_FLAG, #00H
    ACALL INIT_TIMER0
    ACALL LCD_CLEAR
LOOP:
    JB START_FLAG, START
    JB STOP_FLAG, STOP
    SJMP LOOP

START:
    CLR START_FLAG
    SETB STOP_FLAG
    MOV STATE, #01H
    SJMP LOOP

STOP:
    CLR STOP_FLAG
    SETB START_FLAG
    MOV STATE, #00H
    SJMP LOOP

INIT_TIMER0:
    SETB EA
    SETB ET0
    SETB TR0
    RET

DISPLAY_TIME:
    MOV A, HOUR
    ACALL DISPLAY_DIGIT
    MOV A, #':'
    ACALL LCD_SHOW_CHAR
    MOV A, MIN
    ACALL DISPLAY_DIGIT
    MOV A, #':'
    ACALL LCD_SHOW_CHAR
    MOV A, SEC
    ACALL DISPLAY_DIGIT
    MOV A, #'.'
    ACALL LCD_SHOW_CHAR
    MOV A, MS
    ACALL DISPLAY_DIGIT
    RET

DISPLAY_DIGIT:
    PUSH ACC
    PUSH PSW
    MOV B, A
    MOV A, #00H
    DIV AB, #10H
    ADD A, #30H
    ACALL LCD_SHOW_CHAR
    MOV A, B
    ANL A, #0FH
    ADD A, #30H
    ACALL LCD_SHOW_CHAR
    POP PSW
    POP ACC
    RET

LCD_INIT:
    MOV DPTR, #LCD_TABLE
    MOV R0, #00H
    MOV A, #38H
    ACALL LCD_CMD_DELAY
    MOV A, #0FH
    ACALL LCD_CMD_DELAY
    MOV A, #01H
    ACALL LCD_CMD_DELAY
    RET

LCD_SHOW_CHAR:
    ACALL LCD_DATA_DELAY
    RET

LCD_CMD:
    CLR RS
    ACALL LCD_WRITE
    RET

LCD_DATA_DELAY:
    MOV R1, #0AH
    DJNZ R1, $
    RET

LCD_CMD_DELAY:
    MOV R1, #1EH
    DJNZ R1, $
    RET

LCD_CLEAR:
    ACALL LCD_CMD
    MOV A, #01H
    ACALL LCD_CMD
    RET

LCD_WRITE:
    MOV A, @DPTR
    MOV P0, A
    SETB EN
    ACALL LCD_DATA_DELAY
    CLR EN
    INC DPTR
    RET

ORG 030H
    DB '0123456789'
LCD_TABLE:
    END

请注意，这只是一个简单的示例代码，具体实现可能需要进行适当修改以适应实际硬件和应用场景。