1. In an electronic calculator, apparatus for selecting one of a plurality of stored programs for execution, comprising: a rotatable program selector device such as a drum; said program selector device having a display portion containing a plurality of human readable representations, each representing one of said plurality of stored programs, said program selector device having a control portion containing machine readable representations corresponding to each of said human readable representations; said machine readable representations being positionable concurrently with the display of corresponding human readable representations upon rotation of said selector device; manual means for rotating said program selector device to enable human viewing and selection of said human readable representations in said display portion of said selector device; and transducer means operable for generating a program start signal in response to a machine readable representation in said control portion of said program selector device corresponding to a manually selected human readable representation of a desired program.