微机原理-8251实验汇编代码

D8251   EQU     460H    ;2号机改为464H Z8251   EQU     462H    ;2号机改为465H DATA    SEGMENT MESS    DB  'Press any key to send,  [!] key to exit ...',0DH,0AH,'$' DATA    ENDS STACK   SEGMENT STA     DW 32 DUP(?) TOP     DW ? STACK   ENDS CODE    SEGMENT  ASSUME  CS:CODE,DS:DATA,SS:STACK go:  MOV     AX,DATA  MOV     DS,AX  MOV     ES,AX  NOP               ;INIT 8251 START  LEA     DX,MESS  MOV     AH,09H  INT     21H  MOV     CX,100  LOOP    $           MOV     DX,Z8251          ;送00  MOV     AL,00H  OUT     DX,AL  MOV     CX,100  LOOP    $  MOV     DX,Z8251          ;送00  MOV     AL,00H  OUT     DX,AL  MOV     CX,100  LOOP    $  MOV     DX,Z8251          ;送00  MOV     AL,00H  OUT     DX,AL  MOV     CX,100  LOOP    $  MOV     DX,Z8251          ;初始化8251  MOV     AL,40H  OUT     DX,AL  MOV     CX,100  LOOP    $  MOV     AL,0CEH        ;设置为8个数据位,两个停止位波特率因子为16  OUT     DX,AL          ;无奇偶校验位  MOV     CX,100  LOOP    $  MOV     AL,25H         ;设为请求发送,允许发送,允许接收状态  OUT     DX,AL  MOV     CX,100  LOOP    $ NOP                       ;INIT 8251 END REC:    MOV     DX,Z8251  MOV     AH,02H WAIT9:  IN      AL,DX             ;有数据送到吗?  AND     AL,AH  JZ      SEND               ;没有数据送到则跳转至发送  MOV     DX,D8251          ;有数据送到则从数据缓冲区读入  IN      AL,DX  CMP     AL,0FFH  JE      REC               ;可能未上电  MOV     DL,AL  MOV     AH,02H            ;显示在屏幕上  INT     21H  CMP     AL,'!'  JE      ED                ;接收到结束符则返回DOS  JMP     REC               ;不是结束符则继续接收 ED:     MOV     AX,4C00H  INT     21H   SEND:   MOV     CX,10  LOOP    $  MOV     DX,Z8251  MOV     AH,01H WAIT8:  IN      AL,DX  AND     AL,AH  JZ      WAIT8             ;发送缓冲器不空则等待  MOV     DL,0FFH  MOV     AH,06H  INT     21H  JZ      REC               ;无键按下则跳回"接收"处  MOV     DX,D8251          ;有键按下则发送相应字符  OUT     DX,AL  CMP     AL,'!'            ;是结束字符则返回DOS  JE      ED1  JMP     REC               ;不是结束字符则跳回"接收"处 ED1:    MOV     AX,4C00H  INT     21H  CODE    ENDS         END  go