585	 Initial Experience With an Operating Multiprogramming System	 The Lewis Research Center has been using various forms and degrees of program simultaneity in the operation of its modified Sperry-Rand Univac Scientific Model computer during the last five years. This simultaneity has evolved from an initial achievement of self-searching input and output to the automatic time sharing of independently coded problems. Several important machine and program system modifications were necessary to accomplish this evolution. Several additional modifications although not required were added to facilitate ease of coding and operation. All modifications had to proceed at a relatively temperate pace to insure that the basic data-reduction work load of the computing center was completed on schedule. Some educationally valuable mistakes were made and their suggested cures often pointed the way to useful future improvements or emphasized some of the basic principles of a multiprogramming system. The material that follows is a description of the evolution of the programming and hardware system which has developed into the present multiprogramming system at Lewis research Center.
