The 80286 was introduced by Intel on February 1, 1982. As the 80186/80188 CPUs were not really significant to personal computing, the 80286 was Intel's
next step processor for micro computers.
Intel added four more address lines to the 8086/80186 design. The 8086, 8088, 80186, and 80188 all contained 20 address lines, giving these processors one
megabyte of addressibility (2^20 = 1MB). The 80286, with its 24 address lines, gives 16 megabytes of addressibility (2^24 = 16 MB).
The most substantial difference between the 80286 and the 8086/8088 is the addition of a protected mode. In protected mode, segment registers became pointers
into a table of memory descriptors rather than being a direct part of the address. Among other things, protected mode allows safe execution of multiple programs at once by
protecting each program in memory. DOS normally operates in real mode, in which segment registers act just as they do in the 8086/8088.
Protected mode is used by Microsoft Windows, IBM's OS/2 and UNIX. (For an introduction to protected mode please refer to this source)
The 80286 is a much more powerful CPU than the 8086, offering 3-6 times the performance of it. The 6 MHz 80286 is the CPU of the IBM AT (Advanced Technology),
which also introduced a 16-bit motherboard and 16-bit expansion bus to the PC world. The IBM AT was introduced in 1985 - three years after introduction
of the 80286.
With the 80286, the first "chipsets" were introduced. The computer chipset is a set of chips that replaced dozens of other
peripheral chips while maintaining identical functionality. Chips and Technologies became one of the first popular chipset companies.
Intel second-sourced the 80286 to ensure an adequate supply of chips to the computer industry. AMD, IBM, and Harris were known to produce 80286 chips as OEM products;
while Siemens, Fujitsu, and Kruger either cloned it or were also second-sources. Between these various manufacturers, the 80286 was offered in speeds ranging from
6 MHz to 25 MHz:
Intel: 6 - 12.5 MHz
Siemens: 8 - 16 MHz
AMD: 8 - 20 MHz
Harris: 10 - 25 MHz
The 80286 was typically made in 3 package versions, each with 68 contacts: a PGA-, CLCC- and a PLCC-package.
Its successor is the 386.
The 286 was widely used in IBM PC compatible computers during the mid to late 1980s.
For more Information on x86 processors please refer to the x86 processor FAQ or CPU+Mainboard FAQ (german).