A programmable command language is described which supports the development of real-time signal and image processing applications. Initially, this language is being targeted for the Datacube Max-Video modular hardware. Command languages are extremely effective for simulating signal and image processing applications, as they reduce the amount of detail the designer has to cope with, and still allow for the representation of arbitrarily complex designs. However, they have found limited applicability in real-time system development because of their inefficient execution and inability to control real-time hardware. This shortcoming typically necessitates a costly manual translation to faster languages for optimum performance (e.g., C). A command language that supports real-time implementation eliminates the need for this translation. This paper describes the features of such a language. The language includes commands for accessing the entire functionality of each specific hardware module, and commands to manipulate data structures and implement program control constructs. The commands can be executed in either an interactive single-step mode, used for off-line debugging, experimentation, and simulation, or grouped together to define a new command which can then be compiled for real-time execution. By means of representative examples, the utility of this language for programming real-time applications will be discussed and contrasted with other available methods.