TITLE SERIAL DATA COMMUNICATION BETWEEN TWO PCS
  .MODEL SMALL
  .STACK
  .DATA
  MESSAGE DB 'Serial communication via COM1, 4800 ,'
  DB 'No P,1 Stop,8-BIT DATA.',0AH,0DH'
  DB ' ANY KEY PRESS IS SENT TO OTHER PC.',0AH,0DH
  DB ' PRESS ESC TO EXIT','$'
  .CODE
  MAIN PROC
  MOV AX,@DATA
  MOV DS,AX
  MOV AH,09
  MOV DX,OFFSET MESSAGE
  INT 21H
  MOV AH,0 
  MOV DX,0 
  MOV AL,0C3H 
  INT 14H
AGAIN: MOV AH,01 
  INT 16H 
  JZ NEXT 
  MOV AH,0 
  INT 16H 
  CMP AL,1BH 
  JE EXIT 
  MOV AH,1 
  MOV DX,0
  INT 14H
NEXT: MOV AH,03 
  MOV DX,0
  INT 14H
  AND AH,01 
  CMP AH,01 
  JNE AGAIN 
  MOV AH,02 
  MOV DX,0
  INT 14H 
  MOV DL,AL 
  MOV AH,02 
  INT 21H
  JMP AGAIN 
EXIT: MOV AH,4CH 
  INT 21H
  MAIN ENDP
  END