local function drawVertLine(x, sy, ey)
  local incr = (sy > ey and -1 or 1) -- direction to loop
  for i = sy, ey, incr do
    term.setTextColor(cl3)
    term.setCursorPos(x, i)
    write('I')
    sleep(spd/2)
    term.setTextColor(cl2)
    term.setCursorPos(x, i)
    write('|')
    sleep(spd/2)
  end
end

local function drawHorizLine(sx, ex, y)
  local incr = (sx > ex and -1 or 1)
  for i = sx, ex, incr do
    term.setTextColor(cl3)
    term.setCursorPos(i, y)
    write('=')
    sleep(spd/2)
    term.setTextColor(cl2)
    term.setCursorPos(i, y)
    write('-')
    sleep(spd/2)
  end
end

local function centerText(msg, y)
  term.setCursorPos( math.floor((totalx - #msg)/2) + (#msg % 2 == 0 and 1 or 0) , y)
  write(msg)
end

local function advert() -- you don't need the params, you have them defined up the top of the script, just use those
  while true do -- since you have parallel.waitForAny, just put a loop, it will stop this when the other function stops
    -- clear the screen
    term.setBackgroundColor(cl4)
    term.clear()
    -- draw the lines
    term.setBackgroundColor(cl1)
    drawHorizLine(2, totalx - 1, 1)
    drawVertLine(totalx, 1, totaly)
    drawHorizLine(totalx - 1, 2, totaly)
    drawVertLine(1, totaly, 1)
    -- draw the text
    term.setBackgroundColor( colors.orange )
    centerText("Casino", totaly / 2)
    sleep(1)
    -- draw the center line
    drawHorizLine(2, totalx - 1, totaly / 2 + 1)
    -- draw the rest of the text
    centerText("Slots", totaly / 2 + 2)
    sleep(2)
  end
  term.clear()
  term.restore()
end

term.redirect( mon ) -- redirect to the monitor so we can just use term calls
parallel.waitForAny(advert, function() coined(pside) end)
term.restore() -- restore the terminal from the monitor to the computer