PPO is similar to MACD. The oscillator is displayed as a percentage so is consistent between all equities.
This script for ToS was created by Mobius.

thinkScript Code
Code:
# PPO
# Mobius
# V01.03.2014
declare lower;
input c = close;
input AvgType = AverageType.Simple;
input nFast = 8;
input nSlow = 13;
input nSmooth = 5;
plot PPO = ((MovingAverage(AverageType = AvgType, c, nFast) -
MovingAverage(AverageType = AvgType, c, nSlow)) /
MovingAverage(AverageType = AvgType, c, nSlow));
PPO.SetPaintingStrategy(PaintingStrategy.Histogram);
PPO.AssignValueColor(if PPO > 0
then color.green
else color.red);
plot smooth = MovingAverage(AverageType = AvgType, PPO, nSmooth);
smooth.SetPaintingStrategy(PaintingStrategy.Line);
smooth.SetDefaultColor(Color.Cyan);
# End Code PPO