NOPAL is a descriptive language used to write specifications for testing a Unit Under Test (UUT) using an automatic test system (ATS). It can also be used for specification of general purpose computation tasks. The NOPAL system generates a program in the ATLAS test programming language that performs the specified testing. A test specification in NOPAL consists of a number of modules, one of which is the main module. The main module contains the overall test specification. The other modules specify each an abstract data type consisting of a data representation for the abstract data type and a set of operations, called modfuns, which can be performed on variables of the abstract data type. Interfaces among modules are provided by means of the abstract data types. Specification of modfuns is given non-procedurally by means of tests. The main module in NOPAL consists of one or more tests. A test, in NOPAL, corresponds to the notion of a physical test on a UUT (Unit Under Test). It specified stimuli,to be applied, measurements to be taken and logic for selecting a diagnosis depending on the passing or failing of the test. The specification of a test is given by conjunctions of stimuli and measurements and assertions of relations. Information about the UUT and ATE (Automatic Test Equipment) can also be included in a module. This allows various interface checks to be performed. The NOPAL program generator analyzes the specification of a module for consistency, completeness and non-ambiguity and generates a number of reports which serve as the documentation for the specification. Finally, if the specification is error-free, it generates a program in the EQUATE-ATLAS test programming language. Programs generated for various modules of a complete specification can simply be put together and executed on RCA EQUATE-ATLAS computer-controlled automatic test equipment. The NOPAL program generator consists of three phases: (1) syntax analysis, (2) specification analysis, verification and sequencing, and (3) code generation. Each of the three phases are described in detail. An illustrative. example is called MINI-RADIOSET is used throughout.