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protected mode Last modified: Monday, May 18, 1998

A type of memory utilization available on Intel 80286 and later model microprocessors. In protected mode, these processors provide the following features: protection: Each program can be allocated a certain section of memory. Other programs cannot use this memory, so each program is protected from interference from other programs. extended memory : Enables a single program to access more than 640K of memory. virtual memory : Expands the address space to over 1GB. multitasking : Enables the microprocessor to switch from one program to another so the computer can execute several programs at once. Although the DOS operating system is not designed to take advantage of these features, some DOS programs can run in protected mode using special drivers. More sophisticated operating system, such as OS/2, Windows, or UNIX, have built-in support for protected mode.

Article on 386 Protected Mode This August 1991 article provides information on 386 benefits, protected vs. real modes, protect mode addressing, and linkers. DOS Protected Mode Interface (DPMI) This is a programmer's reference copy of the DOS Protected Mode Interface, a protected mode API specification for DOS extended applications. Protected Mode Basics Provides a lengthy and detailed explanation of protected mode and how the CPU handles it internally, the role of memory management, and how to enter and exit protected mode. Technote on CPU addressing modes This page includes full descriptions of each CPU addressing mode, including protected mode, with a diagram of how it works. Utilized Protected Mode features page This page highlights the key advantages of using protected mode. What impact does protected mode have on my code? This page notes both the impact protected mode has on performance, and what influences the performance of protected mode programs.