MEDM, which is derived from Motif Editor and Display Manager, is the primary graphical user interface to the EPICS control system and has also been used for other control systems. MEDM has two modes of operation, EDIT and EXECUTE. In its EDIT mode it provides the drawing tools needed to design control screens for operator interfaces. In its EXECUTE mode it manages those screens to communicate with the control system. MEDM provides a set of interface objects that falls into three main categories: (1) Monitors, such as text, meters, and plots; (2) Controllers, such as buttons, menus, and sliders; and (3) Drawing Objects, such as lines, rectangles, and images. Each of these objects has many options, allowing for the development of screens ranging from simple to quite sophisticated. MEDM has been developed over the last decade, primarily at Argonne National Laboratory, and is a large, well tested, extensively used program. It runs on most flavors of UNIX, VMS, and Windows 95/98/NT. It has been used to design thousands of control screens, such as the one shown in Fig. 1, at the Advanced Photon Source and other sites around the world. This paper presents an overview of MEDM and its features
