Design decisions in a Pascal-based operant conditioning system

FREDL, a Pascal-based system for control of operant experiments, has been implemented on the IBM PC computer. In the foreground, recurring operations, such as decrementing counters that serve as local clocks, are controlled by a dictionary specifying automatic properties of user defined variables, and random logic is implemented by a user-written Pascal overlay. In the background, the remainder of the program controls communication with the user, output of data to disk, and production of cumulative records.