Abstract: A ribbon cassette is provided with a rotatably mounted ribbon supply spool whose flange has markings, angularly spaced according to ribbon type, which are adapted to be successively sensed as ribbon is incrementally drawn off a supply spool to provide signals from which the type of ribbon in the cassette can be identified and the feed increments therefore determined, and information regarding the supply of ribbon remaining on the spool, end of ribbon and ribbon jams may be derived in a programmed control unit. The ribbon cassette further comprises a two-armed lever pivotally mounted in the cassette housing, having first and second lever arms which engage teeth on the edge of the spool flange when the two-armed lever is in a first end condition and a second end condition respectively.