The PILOT data processor is a high-speed multiple computer system, more than 100 times faster than SEAC. It contains three interconnected computers for rapid processing of data, and also contains multiple input-output channels for rapid transfer of data into and out of the system. All of these units operate concurrently in a coordinated fashion. A summary description is given of the over-all logical plan of the system, including the principal characteristics of the first computer, the second computer, the third computer, the internal controls, and the external controls. The system combines internal processing capabilities that are fast and versatile with external communication capabilities that are exceptionally flexible. This combination permits the internal power of the machine to be exploited readily by the outside world,—either by other automatic devices or by human operators.