startup.lua

modem = peripheral.wrap("bottom")
monitor = peripheral.wrap("top")

isSpawning = false

function writeCenter(text)
    x, y = monitor.getSize()
    x2, y2 = monitor.getCursorPos()

    monitor.setCursorPos(math.ceil((x / 2) - (text:len() / 2)), math.ceil(y / 2))
    monitor.write(text)
end

function switchOn()
    modem.transmit(81, 81, "on")

    monitor.setBackgroundColor(colors.green)
    monitor.clear()
    writeCenter("Slaughtering hard")
end

function switchOff()
    modem.transmit(81, 81, "off")

    monitor.setBackgroundColor(colors.red)
    monitor.clear()
    writeCenter("Click to start slaughtering")
end

switchOff()

while true do
    event, side, xPos, yPos = os.pullEvent("monitor_touch")

    if isSpawning == true then
        isSpawning = false
        switchOff()
    else
        isSpawning = true
        switchOn()
    end
end