SIRC V0.1

print("WARNING...")
w,h = term.getSize()

lineno = 1
rednet.open("back")

function listenForMessages()
  while true do
     local id, msg = rednet.receive()
     if lineno == 16 then lineno = 1 end
     local oldx,oldy = term.getCursorPos()
     term.setCursorPos(1, lineno)
     term.clearLine()
     if string.find(msg, "::") then
       term.write(string.gsub(msg, "::", ":"))
     else
       term.write(id..":"..msg)
    end
     term.setCursorPos(oldx, oldy)
  end
     lineno = lineno + 1
end

function sendMessages()
  term.setCursorPos(1, h-1)
  while true do
    message = io.read()
    if message == "quit" then break end
    rednet.broadcast(os.getComputerLabel().."::"..message)
    term.setCursorPos(1, lineno)
    term.write(os.getComputerLabel()..":"..message)
    lineno = lineno + 1
    term.setCursorPos(1, h-1)
    term.clearLine()
  end
end

term.clear()
term.setCursorPos(1, h-2)
term.write(string.rep("*", w))

parallel.waitForAny(sendMessages,
 listenForMessages)