The design and operation of a time-sharing monitor are described. It runs under OS/360 MVT that supports multiple application program interaction with operators of CRT (cathode ray tube) display stations and of a teletype. Key design features discussed include: 1) an interface allowing application programs to be coded in either PL/I or assembler language; 2) use of the teletype for subsystem control and diagnostic purposes; and 3) a novel interregional conduit allowing an application program running under the Chapel Hill Alphanumeric Terminal (CHAT) monitor to interact--like a terminal operator--with a conversational language processor in another region of the OS/360 installation. (Author)