Excerpted from "TSX-Plus User's Reference Manual" TSX-Plus is a high performance operating system for Digital Equipment Corporation PDP-11 and LSI-11 computers, supporting as many as fourty concurrent time-sharing users. TSX-Plus provides a multi-user programming environment that is similiar to extended memory (XM) RT-11. - TSX-Plus keyboard commands are compatible with those of RT-11. - TSX-Plus supports most RT-11 system service calls (EMTs). - Most programs that run under RT-11 will run without modification under TSX-Plus. This includes RT-11 utility programs such as PIP, DUP, DIR, LINK, and MACRO. - TSX-Plus uses RT-11 XM version device handlers. - TSX-Plus provides PLAS extended memory services such as virtual overlays and virtual arrays, as well as support for extended memory regions. TSX-Plus can simultaneously support a wide variety of jobs and programming languages includinf COBOL-Plus, FORTRAN, BASIC, DIBOL, Pascal, C, MACRO, IND, TECO, and KED. TSX-Plus is used in education, business, scientific, and industrial environments. It can concurrently support commercial users doing transaction processing, engineering users performinf scientific processing, system programmers doing program development, and real time process control. Numerous software packages compatible with TSX-Plus are available from other vendors. TSX-Plus supports RT-11 system service calls (EMTs) as its basic mode of operation. The result is low system overhead and substantially improved performance over systems that emulate RT-11 services. TSX-Plus overlaps terminal interaction time, I/O wait time, and CPU execution time for all jobs on the system. In addition to the basic RT-11 functionality, TSX-Plus provides extended features such as: process windows; shared file record locking; inter-job message communication; program performance monitoring; command file parameters; logon and usage accounting; directory and data caching; multitasking; and system I/O buffering. TSX-Plus will run on any PDP-11 or LSI-11 computer with memory management hardware and at least 128Kb of memory. The system must also have a disk suitable for program swapping (the swapping disk can be used for regular file storage as well). Time-sharing lines and serial printers may be connected to the system through DH(U,V,Q)-11, DL(V)-11, or DZ(V)-11 communication devices. Both hardwired and dial-up time-sharing lines are supported by TSX-Plus.