Abstract: A method and machine for testing data processing systems wherein the test result is an acceptance or another condition for the central processing unit of the data processing system. For each data processing system having an intended configuration, the method embodies one or more test programs, each program requiring a predetermined configuration of peripheral devices, the execution of a specific test program being started only after the verification of the presence of the required peripheral. In the absence of an intended peripheral, the test machine has means for simulating the presence of said peripheral device. The determination of the peripherals in a configuration and the selection of a test program from a library of such programs may be automatic or may be chosen by operator input.