System developments in the ACT language: Towards machine independence

ACT (the Automated Contingency Translator) is a list-processing state-oriented sequence control language for on-line control and data acquisition of psychological experiments. Since 1967, ACT software has been progressively expanded and the machine base extended from the PDP8 family to the PDP9, NOVA, and the PDP11. The most recent variant of this language, designated ACT-N, removes previous arbitrary restrictions on state network complexity, expands the conversational repertoire, and adds a subset of compatible BASIC to ACT, thereby giving the package greatly increased computational powers and data storage facilities.