Since April 1965, IBM and the W. W. Hansen High-Energy Physics Laboratory at Stanford University have been engaged in a joint study of use of on-line computers in high-energy physics experiments. In the High-Energy Laboratory, electrons with energies up to 1.2 BeV, produced by the Stanford Mark III 310-ft linear accelerator, are allowed to bombard various target materials. Electrons, or secondary particles produced by the electrons, are detected with several different kinds of detectors. Information from the detectors is relayed to the data-acquisition area where it is processed and stored, while control information is fed back to nuclear instrumentation by the computer. This paper not only contains a description of the computer and instrument interfaces, but also the application-oriented programming approaches used to operate these devices in various experiments. Several different experiments using the data-acquisition computer system are described, and plans for future modifications and improvements are discussed.