Abstract This paper describes the design and implementation of a Net Change Material Requirements Planning (MRP) System on an Apple II Plus microcomputer. MRP is identified as a flow control system. Reference is made to regenerative MRP and Net Change MRP and the distinction between the two systems is identified. An initial — Mark 1 — design of a regenerative MRP system is reviewed. The net change MRP package design is described in detail. The data base is outline with specifications of the Master Parts File, the Bill of Materials File and the Requirements File. The interrelationship between these files is presented and outline flowcharts of the major subprograms are provided. Some sample outputs from the system are discussed. Finally, these limitations of the system, together with ideas for future enhacements are presented. A complete listing of the program is available as an Appendix.