A multiple train control system named KATO Digital was introduced in the late 1980s for HO scale model trains. Conceptually it is similar to Digital Command Control (DCC). Although an important milestone for Kato, KATO Digital was not very successful; both the controller units and the decoder modules required for the locomotives were expensive, and locomotives equipped with a KATO Digital decoder could not be used on conventional systems, making it difficult to run one's locomotives on friends' layouts or club layouts.
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