Editing Carnegie Mellon's Harpy System (section)

==== '''5.1 Prior state information saving''' ====
The Harpy system optimized the prior state information saving strategy in Dragon system to reach higher recognition speed. Harpy saves a small number of prior states (100 times samples worth) in memory at a time and when more room is needed, they are saved on external storage (a high speed drum). For the algorithms, Harpy calculates the probabilities by logs and thus do addition, which eliminates the need to scale.