Simple Clock

mon = peripheral.wrap("top")
mon.setTextScale(4)
x = 0 -- x is seconds
y = 0 -- y is minutes
z = 0 -- z is hours
while true do
  mon.clear()
  mon.setCursorPos(1, 1)
  mon.print(z..":"..y..":"..x)
  sleep(1)
  x = x + 1
  if x == 60 then
    x = 0
    y = y + 1
  end
  if y == 60 then
    y = 0
    z = z + 1
    if z == 24 then
      z = 0
    end
  end
end