【正文】 MOV BX,0 MOV AH,14 INT 10H JMP FOREVER BEGIN ENDP CODE ENDS END START 。 MOV BL,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H JMP FOREVER1 B0: MOV AL,0AH MOV BL,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H JMP B1 B5:JMP OK B6:JMP B7 RECEIVE: MOV DX,3F8H IN AL,DX AND AL,7FH CMP AL,0DH JZ XS MOV [DI],AL INC DI INC CH JMP FOREVER1 XS: LEA DI,REC B4: MOV AL,[DI] CMP AL,0DH JZ B3 DEC CH JS B3 MOV BL,0 MOV AH,14 INT 10H INC DI JMP B4 B1: LEA SI,SED B2: MOV AL,[SI] INC SI MOV DX,3F8H OUT DX,AL DEC CL JNZ B2 LEA SI,SED JMP FOREVER1 B3: MOV AL,0AH MOV BL,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H MOV CH,0 LEA DI,REC JMP FOREVER1 BEGIN ENDP CODE ENDS END START 上位機(jī)程序 3：不用發(fā)請求聯(lián)絡(luò)信號，雙方可直接通信，按回車發(fā)送 STACK SEGMENT DB 256 DUP(0) STACK ENDS DATA SEGMENT FS DB 256 DUP (?) ；定義發(fā)送字符緩沖區(qū) DATA ENDS CODE SEGMENT ASSUME CS:CODE,DS:DATA,SS:STACK BEGIN PROC FAR PUSH DS ；保存 PSP 段地址 XOR AX,AX PUSH AX ；保存返回地址偏移值 START: ；初始化 8250 為： 8 位數(shù)據(jù)位， 1 位停止位，無校驗(yàn)，波特率 9600 MOV AX,DATA MOV DS,AX LEA SI,FS MOV DX,3FBH MOV AL,80H OUT DX,AL MOV DX,3F8H MOV AL,0CH OUT DX,AL MOV DX,3F9H MOV AL,0 OUT DX,AL MOV DX,3FBH MOV AL,03H OUT DX,AL MOV DX,3FCH MOV AL,03H ； 內(nèi)部輸出輸入不反接 OUT DX,AL MOV DX,3F9H MOV AL,0 ；禁止中斷，采用查詢方式進(jìn)行信息交換 OUT DX,AL XOR CX,CX FOREVER: ；查詢循環(huán)程序 MOV DX,3FDH IN AL,DX TEST AL,1EH JNZ ERROR TEST AL,01H JNZ RECEIVE TEST AL,40H ；測發(fā)送移位寄存器是否為空，不空繼續(xù)查詢 JZ FOREVER TEST AL,20H ；測發(fā)送保持寄存器是否為空，不空返回查詢 JZ FOREVER MOV AH,1 ；空就測鍵盤緩沖區(qū)是否有字符 INT 16H JZ FOREVER ；無就返回查詢 MOV AH,0 INT 16H MOV [SI],AL ；有就存入到發(fā)送緩沖區(qū)，同時 CX 作為計(jì)數(shù)寄存器 INC SI INC CX CMP AL,0DH ；是否為回車發(fā)送，是就轉(zhuǎn)發(fā)送處理 JZ B0 MOV BX,0 ；不是就將按鍵顯示 MOV AH,14 INT 10H JMP FOREVER B1: LEA SI,FS ；取發(fā)送緩沖區(qū)首地址，將暫存的發(fā)送 B2: MOV AL,[SI] INC SI MOV DX,3F8H OUT DX,AL DEC CX JNZ B2 ；沒發(fā)完繼續(xù)發(fā) LEA SI,FS ；發(fā)完使地址指針歸位 JMP FOREVER B0: MOV AL,0AH ；若為回車就 先換行 MOV BX,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H JMP B1 ；再轉(zhuǎn)一個個發(fā)送 RECEIVE: MOV DX,3F8H IN AL,DX AND AL,7FH ；取接收數(shù)據(jù)的低七位 CMP AL,30H ；比較是否為 0 JZ B3 ；為 0 就轉(zhuǎn) B3 換行 MOV BX,0 ；不是就一個個顯示 MOV AH,14 INT 10H JMP FOREVER B3: MOV AL,0AH ；換行程序 MOV BX,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H JMP FOREVER ERROR: ；出錯處理程序 MOV DX,3F8H IN AL,DX MOV AL,39。 MOV BL,0 MOV AH,14 INT 10H MOV AL,61H MOV BL,0 MOV AH,14 INT 10H MOV AL,69H MOV BL,0 MOV AH,14 INT 10H MOV AL,74H MOV BL,0 MOV AH,14 INT 10H MOV AL,69H MOV BL,0 MOV AH,14 INT 10H MOV AL,6EH MOV BL,0 MOV AH,14 INT 10H MOV AL,67H MOV BL,0 MOV AH,14 INT 10H MOV AL,2EH MOV BL,0 MOV AH,14 INT 10H MOV AL,2EH MOV BL,0 MOV AH,14 INT 10H MOV AL,2EH MOV BL,0 MOV AH,14 INT 10H FOREVER: MOV DX,3FDH IN AL,DX TEST AL,1EH JNZ B9 TEST AL,01H JNZ WS JMP FOREVER WS:MOV DX,3F8H IN AL,DX AND AL,7FH MOV [BP],AL INC BP CMP AL,0DH JZ B8 JMP FOREVER B7: MOV AL,4EH MOV BL,0 MOV AH,14 INT 10H MOV AL,4FH MOV BL,0 MOV AH,14 INT 10H MOV AL,21H MOV BL,0 MOV AH,14 INT 10H MOV AL,0AH MOV BL,0 MOV AH,14 INT 10H MOV DL,0DH MOV AH,2 INT 21H JMP FOREVER B9:JMP ERROR B8:JMP B5 OK:LEA BP,ZS MOV AL,[BP] CMP AL,37H JNZ B6 MOV AL,4FH MOV DX,3F8H OUT DX,AL MOV AL,4BH MOV DX