mon = peripheral.wrap("back")
mon.setTextScale(4)
strtpos = 12
speed = 0.2
text = "Rush's Shop!"

pos = strtpos
poslimit = 0 - strtpos

while true do
 mon.clear()
 mon.setBackgroundColor(32768)
 mon.setTextColor(16384)
 mon.setCursorPos(pos, 2)
 mon.write(text)
 sleep(0.3)
 if pos == poslimit then
  pos = strtpos
 else
  pos = pos - 1
 end
end