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The Intel 80286 (also marketed as the iAPX 286〔(Official Intel iAPX 286 programmers' manual ) (page 1-1)〕 and often called Intel 286) is a 16-bit microprocessor that was introduced on 1 February 1982. It was the first 8086 based CPU with separate, non-multiplexed, address and data buses and also the first with memory management and wide protection abilities. The 80286 used approximately 134,000 transistors in its original nMOS (HMOS) incarnation and, just like the contemporary 80186,〔A simpler cousin in the 8086-line with integrated peripherals, intended for embedded systems.〕 it could correctly execute most software written for the earlier Intel 8086 and 8088 processors. The 80286 was employed for the IBM PC/AT, introduced in 1984, and then widely used in most PC/AT compatible computers until the early 1990s. ==History and performance== After the 6 and 8 MHz initial releases, Intel subsequently scaled it up to 12.5 MHz. AMD and Harris later pushed the architecture to 20 MHz and 25 MHz, respectively. Intersil and Fujitsu also designed fully static CMOS versions of Intel's original depletion-load nMOS implementation, largely aimed at battery powered devices. On average, the 80286 was reportedly measured to have a speed of about 0.21 instructions per clock on "typical" programs, although it could be significantly faster on optimized code and in tight loops as many instructions could execute in 2 clock cycles. The 6 MHz, 10 MHz and 12 MHz models were reportedly measured to operate at 0.9 MIPS, 1.5 MIPS and 2.66 MIPS respectively. The later E-stepping level of the 80286 was free of the several significant errata that caused problems for programmers and operating system writers in the earlier B-step and C-step CPUs (common in the AT and AT clones).〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Intel 80286」の詳細全文を読む スポンサード リンク
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