Terminate and Stay Resident (TSR)

A terminate and stay resident (TSR) is a software program that resides in a computer’s memory until it is called upon to execute.TSR programs were initially developed for single-tasking disk operating systems (DOSs). Computers that run under a DOS are only able to execute one program at a time, but with the help of TSRs they can allow programs to switch between tasks without having to reload the entire program. When a TSR is installed on a computer, a control character, otherwise referred to as a hotkey, is assigned to it. Once a computer user opens a software program, they can press the hotkey to immediately execute the TSR program. Examples of TSR programs include spell checkers, calendars, notepads, and antivirus software. However, today, DOSs are not commonly used in the business world. Most corporations use multitasking operating systems that are capable of task switching without the help of TSRs.