http://www.mikroe.com/en/books/picbasicbook/06.htm#6.3


program Timer0_1sec

dim cnt as byte
dim  a as byte
dim  b as byte

sub procedure interrupt
  cnt = cnt + 1        ' Increment value of cnt on every interrupt
  TMR0   = 96
  INTCON = $20         ' Set T0IE, clear T0IF
end sub

main:

a = 0
b = 1
OPTION_REG = $84      ' Assign prescaler to TMR0
TRISB  =   0          ' PORTB as output
PORTB  = $FF          ' Initialize PORTB
cnt =   0             ' Initialize cnt
TMR0   =  96
INTCON = $A0          ' Enable TMRO interrupt

' If cnt is 200, then toggle PORTB LEDs and reset cnt
do
  if cnt = 200 then
    PORTB  = not(PORTB)
    cnt = 0
  end if
loop until 0 = 1

end.