memory resident

Present in the main (RAM) memory of the computer. For an application to be run, it has to be memory resident. In the MS-DOS operating system, some applications were kept in memory (see terminate and stay resident), while most were deleted from the memory when their task was complete. However, under MS-DOS the memory was usually not large enough to hold all applications and swapping in and out of memory was necessary. This technique has become defunct with the introduction of multi-tasking operating systems such as Windows XP.