The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982.
Linux on 286 laptops and notebooks Intel 80286 images and descriptions at cpu-collection.de CPU-INFO: 80286, in-depth processor history Overview of all 286 compatible chips Intel 80286 CPU Information, including chip errata and undocumented behaviour Intel 80286 Hardware Reference Manual Computer-related introductions in 1982 80286 16-bit microprocessors
In the PC/AT introduced in 1984, IBM added external circuitry, as well as specialized code in the ROM BIOS and the 8042 peripheral microcontroller to enable software to cause the reset, allowing real-mode reentry while retaining active memory and returning control to the program that initiated the reset.
It was arguably responsible for the split between Microsoft and IBM, since IBM insisted that OS/2, originally a joint venture between IBM and Microsoft, would run on a 286 (and in text mode). Other operating systems that used the protected mode of the 286 were Microsoft Xenix (around 1984), Coherent, and Minix.
In protected mode, registers were still 16-bit, and the programmer was still forced to use a memory map composed of 64 kB segments, just like in real mode. In January 1985, Digital Research previewed the Concurrent DOS 286 1.0 operating system developed in cooperation with Intel.
This E-2 stepping part may have been available in later 1986. ==Architecture== Intel did not expect personal computers to use the 286. The CPU was designed for multi-user systems with multitasking applications, including communications (such as automated PBXs) and real-time process control.
For example, in 1986 the only program that made use of it was VDISK, a RAM disk driver included with PC DOS 3.0 and 3.1.
Named IBM 4680 OS, IBM originally chose DR Concurrent DOS 286 as the basis of their IBM 4680 computer for IBM Plant System products and point-of-sale terminals in 1986.
Digital Research's FlexOS 286 version 1.3, a derivation of Concurrent DOS 286, was developed in 1986, introduced in January 1987, and later adopted by IBM for their IBM 4690 OS, but the same limitations affected it. The problems led to Bill Gates famously referring to the 80286 as a "brain-dead chip", since it was clear that the new Microsoft Windows environment would not be able to run multiple MS-DOS applications with the 286.
Digital Research's FlexOS 286 version 1.3, a derivation of Concurrent DOS 286, was developed in 1986, introduced in January 1987, and later adopted by IBM for their IBM 4690 OS, but the same limitations affected it. The problems led to Bill Gates famously referring to the 80286 as a "brain-dead chip", since it was clear that the new Microsoft Windows environment would not be able to run multiple MS-DOS applications with the 286.
In the Soviet Union a clone of the 80286 was designated KR1847VM286 (КР1847ВМ286|italic=yes). LOADALL – Undocumented 80286/80386 instruction that could be used to gain access to all available memory in real mode. Windows/286 iAPX, for the iAPX name ==References== ==External links== Intel Datasheets Intel 80286 and 80287 Programmer's Reference Manual at bitsavers.org Intel 80286 Programmer's Reference Manual 1987 (txt).
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