CSEG AT 0
JMP start
CSEG AT 100
start:
     MOV TH0,#76
     MOV TL0,#01
     MOV TMOD,#01

     MOV A, R0
loop:
     JNB P3.0, pressed
     JB P3.0, relased
mainp:
     JNB TF0,loop
     INC A
     DEC P2
     CLR TF0
     JMP loop
pressed:
     SETB TR0
     JMP mainp
relased:
     CLR TR0
     JMP mainp
END