The design and performance evaluation of a multiprocessor system are described. The system consists of processing units sharing the processing of the same instruction stream, where tasks consist of individual instructions. The multiprocessing aspect is completely transparent to the user. The system configuration developed calls for two microprogrammed processing units sharing the same local and control stores. Simulated execution of instruction sequences demonstrated a 20 percent increase in instruction processing speed over that for a single CPU. A companion study  shows even better performance (37 percent increase) with a different mode of interaction. This improved performance and substantially increased availability can be achieved at the cost of a single board of LSI logic. Copyright © 1973 by The Institute of Electrical and Electronics Engineers, Inc.