local text = "alien team house!   "
local checksum = 15764

--------------------------------

local monitor = peripheral.wrap("back")
monitor.setTextScale(5)
monitor.setBackgroundColor(colors.black)
monitor.setTextColor(colors.orange)

--------------------------------

local sizeX, sizeY = monitor.getSize()
local pos = 1

local function mathChecksum(data)
    local number = 0
    for i = 1, #data do
        number = number + (data:byte(i) * i)
    end
    --print("valid", number)
    return number
end

if mathChecksum(text) == checksum then
    while true do
        monitor.clear()
        monitor.setCursorPos(1, 1)

        local str = text:sub(pos, pos + (sizeX - 1))

        do
            local index = 1
            while #str < sizeX do
                str = str .. text:sub(index, index)
                index = index + 1
            end
        end

        monitor.write(str)

        pos = pos + 1
        if pos > #text then
            pos = 1
        end

        sleep(0.5)
    end
else
    monitor.clear()
    monitor.setBackgroundColor(colors.red)
    monitor.setTextColor(colors.orange)
    monitor.setCursorPos(1, 1)
    monitor.write("rootmaster loh   ")
    while true do
        sleep(1)
    end
end