MOV       TMOD, #20H            ; Timer 1 is in mode 2
          MOV       TH1,  # -3            ; 9600 baud rate
          MOV       SCON, #50H            
          MOV       P0, # 'B' 
          MOV       P1, # 'E'
          MOV       P2, # 'S'
          MOV       P3, # 'T'              ; make P0, P1, P2 & P3 as input ports
          SETB      TR1                    ; Start timer 1
REPEAT:   MOV       A, P0
          ACALL     GO
          MOV       A, P1
          ACALL     GO
          MOV       A, P2
          ACALL     GO
          MOV       A,P3
          ACALL     GO
          SJMP        REPEAT

GO:       MOV SBUF, A                     ; Loading data into SBUF 
 HERE:    JNB    TI, HERE                 ; Wait till transmission ends
          CLR    TI                       ; Clear TI for next transmission  
          RET