Patent US 4,489,429

In order to provide a visual indication of the location of error in stored programs and allow easy and prompt correction for the error, a programmable calculator is provided with both a display device (preferably, a cathode ray tube) capable of displaying the contents of a plurality of consecutive program steps in a program memory at the same time and adapted for selectively displaying the plurality of the consecutive program steps in a stepwise manner and a sound or voice synthesizer for sequentially providing verbal indications of the contents of the consecutive program steps being visually displayed. It thus becomes possible to check a program just introduced by virtue of a verbal indication of the program derived from the verbal indication means and, in the event that an error has been found, immediately stop programming and correct readily and quickly for the error, since the visual display provides a series of consecutive program steps simultaneously to assist the operator in finding where the error is present in the program during a learning mode or thereafter.