Abstract: In a computer system, a plurality of commands selected by an operator are sequentially inputted to specify respective processing to be executed and respective data to be used in the processing. Each of the inputted commands is executed before an input of a command subsequent thereto to output data resultant from an execution of the command. In the input operation, several commands are supplied to specify, as data to be respectively used by the plural commands, resultant data attained by the execution of commands inputted prior thereto. From the plural input commands are extracted a series of several commands employed to generate at least one resultant data associated with the plural commands and selected by the operator. Based on the extracted command series, there is generated a program executing processing to be achieved by the command series or processing equivalent thereto.