An investigation of the interaction between man and computer in a countdown environment. Possible benefits and problems of extending computer control are also explored. The demonstration test examines countdown from the executive control level, i.e., launch director, test supervisor, or launch-vehicle test conductor. Tests and operations appear as in a normal countdown script. Major hardware test components consist of the computer and the RAND Tablet, a man/machine graphical communication device. Using the RAND graphic system, the executive can experiment, interrogate, predict, issue commands, and receive responses on a cathode ray tube display from the central processing unit. Outputs presented include information dealing with time, script, status, and operational and engineering data. The test introduces an innovation that enables the executive to act online with a simulation of the countdown: he can make changes to the script or to the simulation. 38 pp.