Protected Mode - History

History

The Intel 8086, the predecessor to the 286, was originally designed with a 20-bit address bus for its memory. This allowed the processor to access 220 bytes of memory, equivalent to 1 megabyte. At the time, 1 megabyte was considered a relatively large amount of memory, so the designers of the IBM Personal Computer reserved the first 640 kilobytes for use by applications and the operating system and the remaining 384 kilobytes for the BIOS (Basic Input/Output System) and memory for add-on devices.

As the cost of memory decreased and memory use increased, the 1 MB limitation became a significant problem. Intel intended to solve this limitation along with others with the release of the 286.

Read more about this topic:  Protected Mode

Famous quotes containing the word history:

    There is one great fact, characteristic of this our nineteenth century, a fact which no party dares deny. On the one hand, there have started into life industrial and scientific forces which no epoch of former human history had ever suspected. On the other hand, there exist symptoms of decay, far surpassing the horrors recorded of the latter times of the Roman empire. In our days everything seems pregnant with its contrary.
    Karl Marx (1818–1883)

    The history of American politics is littered with bodies of people who took so pure a position that they had no clout at all.
    Ben C. Bradlee (b. 1921)

    In the history of the United States, there is no continuity at all. You can cut through it anywhere and nothing on this side of the cut has anything to do with anything on the other side.
    Henry Brooks Adams (1838–1918)