LYCOS RETRIEVER 
Intel 80286
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The Intel 80286 CPU, released in 1982, was the successor to the little-used 80186. The 286 offered 3 to 6 times the performace of the 8086. The first models ran at 6 Mhz, and eventually the 286 reached 12.5 Mhz.
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The Intel 80286 is a 16-bit processor. It contained 134,000 transistors, and was a 2.66 MIP (Million Instructions Per Second), 12 Mhz chip. Introduced in 1982, the chip shown is from 1984. The chip shown has flat gold contacts and was probably designed for small spaces such as laptops.
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The Intel 80286 could support 8086 Real Mode 16-bit software without any changes... it also supported another mode of work called the Protected Mode, which expanded addressable memory to 16MB. This was done by using the segment registers only for storing an index to a segment table. The segment table provided a 24-bit base address, which could then be added to the desired offset to create an absolute address. In addition, each segment could be given one of four privilege levels (called the rings). Overall, the introductions were an improvements; however they were not used widely per se because using Protected Mode made software incompatible with the Real Mode of 8086.
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The second generation of x86 16-bit processors, Intel 80286, was released in 1982. The major new feature of the 80286 microprocessor was protected mode. When switched to this mode, the CPU could address up to 16 MB of operating memory (previous generation of 8086/8088 microprocessors was limited to 1 MB). In the protected mode it was possible to protect memory and other system resources from user programs - this feature was necessary for real program multitasking. There were many operating systems that utilized the 80286 protected mode: OS/2 1.x, Venix, SCO Xenix 286, and others. While this mode was useful for multitasking operating systems, it was of limited use for systems that required execution of existing x86 programs.
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Chapter 1 introduces the Intel family of microprocessors with an emphasis on the 80286 microprocessor. This first chapter serves to introduce the microprocessor, its history, its operation, and the methods used to store data in a microprocessor-based system. Once an understanding of these basic machine is grasped, Chapters 2--5 explain how each instruction functions with the 80286 microprocessor. As instructions are explained, simple applications are presented to illustrate the operation of the instructions and develop basic programming concepts.
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AMD used the same naming convention for 80286 processors as Intel. Earlier processors in ceramic leadless chip carrier package were named "C80286-<frequency>". In 1985 the naming convention for CLCC processors was changed to "R80286-<frequency>". Interesting that the earlier processors (up until 1986) had AMD copyright.
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Intel 80286