asample1.a51

c51学习的好书！

NAME    SAMPLE
EXTRN   CODE    (PUT_CRLF, PUTSTRING)
PUBLIC  TXTBIT
PROG    SEGMENT CODE
CONST   SEGMENT CODE
VAR1    SEGMENT DATA
BITVAR  SEGMENT BIT
STACK   SEGMENT IDATA
        RSEG  STACK
        DS    10H                 ; 为堆栈保留16个字节
        CSEG  AT   0
        USING   0                 ; 选择工作寄存器组 0
        JMP   START               ; 复位时程序的执行起点
        RSEG  PROG
START:  MOV   SP,#STACK-1         ; 初始化堆栈指针
        ; 下列命令初始化定时器T0和串行口以产生波特率
        MOV   TMOD,#00100000B     ; C/T = 0, Mode = 2
        MOV   TH1,#0FDH
        SETB  TR1
        MOV   SCON,#01010010B
        CLR   TXTBIT
        ; 下面是主程序, 它从串行口输出字符
REPEAT: MOV   DPTR,#TXT
        CALL  PUTSTRING
        CALL  PUT_CRLF
        SJMP  REPEAT
        RSEG  CONST
TXT:    DB    'TEST PROGRAM',00H
        RSEG  VAR1
DUMMY:  DS    21H
        RSEG  BITVAR
TXTBIT: DBIT  1
        END