Problem—Loading Entire Task into Memory is Wasteful

Consider the following scenario:

  1. A machine has 256MB of RAM memory (a ridiculously small amount, but this is just an example, after all).

  2. The ROM-based Power-On Self-Test (POST) completes execution and the boot program reads (i.e., boots) the OS loader program into memory.

  3. The OS loader reads the entire OS into memory, consuming 250MB of memory (this is just an example; in this day and age, it would be amazing if an OS were this small). The OS is a multitasking OS, permitting the end user to start multiple programs. The OS rapidly timeslices between them, giving the appearance that all of the programs run simultaneously.

  4. The user tells the OS to start a word processing program. In response, the ...

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