;P2.6 = WR (start conversion needs to L-to-H pulse)
;P2.7 When low, end-of-conversion)
;P2.5 = RD (a H-to-L will read the data from ADC chip)
;P1,0 - P1.7 = D0 - D7 of the ADC804
;
          MOV  P1,#0FFH  ;make P1 = input
BACK:     CLR  P2.6      ;WR=0
          SETB P2.6      ;WR=1 L-to-H to start conversion
HERE:     JB   P2.7,HERE ;wait for end of conversion
          CLR  P2.5      ;conversion finished,enable RD
          MOV  A,P1      ;read the data
          ACALL CONVERSION    ;hex-to-ASCII conversion
          ACALL DATA_DISPLAY  ;display the data
          SETB P2.5      ;make RD=1 for next round
          SJMP BACK