ABM Server WIP v3

-[[Settings]]--
local waitDelay = 2
local countersPerMissile = 1
local missileDelay = 3

--[[Initialization]]--
local silos, curSilo = {}, 1
local siloData = {}
peripheral.find("modem", rednet.open)
term.setBackgroundColor(colors.blue)

local function red()
term.setBackgroundColor(colors.red)
print("                                                   ")
term.setBackgroundColor(colors.blue)
end

rednet.broadcast("ABM1")
repeat
    local id, msg, status = rednet.receive(waitDelay)
    if msg == "ABM" then
 table.insert(silos, id)
table.insert(siloData, missile)

end
until not id

--[[Main Programs]]--
while true do
    if not redstone.getInput("back") then
        term.clear()
        term.setCursorPos(1, 1)

        red()
        print("        SKYNET DEFENSE SYSTEMS ACTIVATED           ")
        red()
        print("      ANTI-BALLISTIC MISSILE SHIELD ONLINE         ")
        red()
        red()
        print("               [STANDBY ABM Silos]                 ")

        for k, v in ipairs(silos) do print("  silo #" .. k .. " id = "..v) end

        red()

        repeat os.pullEvent("redstone") until redstone.getInput("back")
    end

    term.clear()
    term.setCursorPos(1, 1)
    term.setTextColor(colors.red)

    print("Incoming Missiles:")
    print("Firing CounterMeasures\n")

 maptab = peripheral.call("back","getEntities")
 maptxt = textutils.serialize(maptab)
 if maptxt ~= "{}" then
 allDat = 0
 for num in pairs(maptab) do
 allDat = allDat+1
 end
 targets = allDat/3
 for i=0,targets-1 do
        local msg = {["x"] = math.floor(maptab["x_"..i]), ["y"] = math.floor(maptab["y_"..i]), ["z"] = math.floor(maptab["z_"..i])}

        print("Incoming Missile Threat #" .. i .. " at X:" .. msg.x .. " Y:" .. msg.y .. " Z:" .. msg.z)
        print("Launching " .. countersPerMissile .. " of ABM Missile CounterMeasures...\n")

        for i = 1, countersPerMissile do
            rednet.send(silos[curSilo], msg)
            curSilo = (curSilo == #silos) and 1 or (curSilo + 1)
            sleep(missileDelay)
            end
        sleep(0)
        end
     sleep(0)
    end
   sleep(2)
end
sleep(1)