This paper describes PUMPS, a microcomputer-based, interactive, and menu-driven software package for use as an educational tool by mechanical engineering students in investigating and understanding hydraulic pumps. The package is written in the Pascal computer language and runs on any IBM PC, or compatible. The program can handle problems related to radial, mixed, or axial flow hydraulic pumps by solving for any unknown variable through a complete set of equations covering all pump installation. Model-prototype problems can also be tackled through similarity laws. Furthermore, the graphical utilities of the package allow the user to display diagrammatic sketches of the pump, to employ some recommended charts, to draw velocity triangles, and to plot pump and pipeline characteristic curves. The most important feature of the program, however, is its ability to plot the variation of any variable versus any other one. Through this option, the package guides the student in understanding the effects of varying design parameters on the overall performance of the machine. Finally, some special features that are important in making the package user-friendly and encouraging-to-use are also available, and the comprehensive example problem provided demonstrates the capabilities of the package as an instructional tool.