An inexpensive experiment controller for stand-alone applications or distributed processing networks

An inexpensive microprocessor-based experiment controller available as a commercially produced bare printed circuit board is described. It provides for up to 8 inputs and 40 outputs. An 8K Experiment Control BASIC (ECBASIC) and a compiled Experiment Control Language (ECL) are also available. Both languages have internal structures that enable time and responses to be dealt with in a very convenient and error-free manner. Time and response count are automatically incrementing variables that need only to be tested by the user program. ECBASIC provides a 10-msec accuracy, whereas ECL provides a l-msec accuracy. ECL provides extensive support for event-driven programs. The board and software are designed to provide an orderly migration from a stand-alone controller running ECBASIC as a relay-rack replacement, to a network of ECBASIC machines on a small computer, to a true error-checking network of ECL machines on a time-sharing operating system of a large computer. Network communication is over the three wires of a single unmodified RS232 asynchronous serial communication line.