Editing Intel 80286

{{Short description|Microprocessor model}}
{{Use mdy dates|date=October 2018}}
{{Infobox CPU
| image = KL Intel i286.jpg
| caption = An Intel A80286-8 processor with a gray ceramic heat spreader
| manuf1 = [[Intel]], [[IBM]], [[AMD]], [[Harris Corporation|Harris]] ([[Intersil]]), [[Siemens]], [[Fujitsu]]
| produced-start = February 1982
| produced-end = 1991<ref>{{cite web |url=https://www.cpushack.com/life-cycle-of-cpu.html |title=CPU History - The CPU Museum - Life Cycle of the CPU |website=cpushack.com |access-date=September 6, 2021 |archive-date=July 20, 2021 |archive-url=https://web.archive.org/web/20210720004826/https://www.cpushack.com/life-cycle-of-cpu.html |url-status=live }}</ref>
| slowest = 4 | slow-unit = MHz
| fastest = 25 | fast-unit = MHz
| fsb-slowest = 4 | fsb-slow-unit = MHz
| fsb-fastest = 25 | fsb-fast-unit = MHz
| transistors = 120,000<ref>Ormsby, John, "Chip Design: A Race Worth Winning", Intel Corporation, Microcomputer Solutions, July/August 1988, page 18</ref> or 134,000, 1.5[[Micrometre|μm]]
| arch = [[x86-16]] (with [[memory management unit|MMU]])
| pack1 = 68-pin [[plastic leaded chip carrier|PLCC]]
| pack2 = 68-pin [[leadless chip carrier|LCC]]
| pack3 = 68-pin [[pin grid array|PGA]]
| pack4 = 100-pin [[PQFP]] (engineering sample only)
| predecessor  = [[8086]], [[8088]] (while [[Intel 80186|80186]] was contemporary)
| successor  = [[Intel 80386]]
| co-processor = [[Intel 80287]]
| data-width = 16 bits
| address-width = 24 bits
| size-from = [[1.5 μm process|1.5&nbsp;μm]]<ref>{{cite web|url=https://en.wikichip.org/wiki/1.5_%C2%B5m_lithography_process|title=1.5 μm lithography process - WikiChip|website=en.wikichip.org|access-date=January 21, 2019|archive-date=September 9, 2018|archive-url=https://web.archive.org/web/20180909090836/https://en.wikichip.org/wiki/1.5_%C2%B5m_lithography_process|url-status=live}}</ref>
| sock1 = PGA68
| sock2 = PLCC-68
| sock3 = LCC-68
| support status = Unsupported
}}

The [[Intel]] '''80286'''<ref>{{cite web |title=Microprocessor Hall of Fame |url=http://www.intel.com/museum/online/hist%5Fmicro/hof/ |publisher=Intel |access-date=August 11, 2007 |archive-url=https://web.archive.org/web/20070706032836/http://www.intel.com/museum/online/hist_micro/hof/ |archive-date=July 6, 2007}}</ref> (also marketed as the '''iAPX 286'''<ref name="i286">{{cite book|url=http://bitsavers.org/components/intel/80286/210498-001_iAPX_286_Programmers_Reference_1983.pdf|title=iAPX 286 Programmer's Reference|at=page 1-1|publisher=Intel|year=1983|access-date=August 28, 2017|archive-date=August 28, 2017|archive-url=https://web.archive.org/web/20170828232803/http://www.bitsavers.org/components/intel/80286/210498-001_iAPX_286_Programmers_Reference_1983.pdf|url-status=live}}</ref> and often called '''Intel 286''') is a [[16-bit computing|16-bit]] [[microprocessor]] that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non-[[Bus (computing)#Bus_multiplexing|multiplexed]] [[address bus|address]] and [[bus (computing)|data buses]] and also the first with [[memory management]] and wide protection abilities. It had a data size of 16 bits, and had an address width of 24 bits, which could address up to 16M of memory with a suitable operating system such as Windows compared to 1M for the 8086. The 80286 used approximately 134,000 transistors in its original [[NMOS logic|nMOS]] ([[depletion-load NMOS logic|HMOS]]) incarnation and, just like the contemporary [[Intel 80186|80186]],<ref>A simpler cousin in the 8086-line with integrated peripherals, intended for [[embedded system]]s.</ref> it can correctly execute most software written for the earlier [[Intel 8086]] and [[Intel 8088|8088]] processors.<ref>{{cite web |url=http://www.intel.com/museum/online/hist_micro/hof/index.htm |title=Intel Museum – Microprocessor Hall of Fame |publisher=Intel.com |date=May 14, 2009 |access-date=June 20, 2009|archive-url=https://web.archive.org/web/20090312081932/http://www.intel.com/museum/online/hist_micro/hof/index.htm |archive-date=March 12, 2009}}</ref>

The 80286 was employed for the [[IBM Personal Computer AT|IBM PC/AT]], introduced in 1984, and then widely used in most PC/AT compatible computers until the early 1990s.  In 1987, Intel shipped its five-millionth 80286 microprocessor.<ref>Teixeira, Kevin, "What's Next For The 80286?", Intel Corporation, Microcomputer Solutions, November/December 1987, page 16</ref>

==History and performance==
[[File:KL AMD 80286 CLCC Bottom.jpg|thumb|AMD 80286 (16 MHz version)]]
Intel's first 80286 chips were specified for a maximum clockrate of 5, 6 or 8&nbsp;[[MHz]] and later releases for 12.5&nbsp;MHz. [[AMD]] and [[Harris Corporation|Harris]] later produced 16&nbsp;MHz, 20&nbsp;MHz and 25&nbsp;MHz parts. Intel, [[Intersil]] and [[Fujitsu]] also designed fully static [[CMOS]] versions of Intel's original [[depletion-load NMOS logic|depletion-load nMOS]] implementation, largely aimed at battery-powered devices. Intel's CMOS version of the 80286 was the 80C286.

On average, the 80286 was said to have a speed of about 0.21 [[Instructions per cycle|instructions per clock]] on "typical" programs,<ref>{{cite web |url=http://www.intel80386.com |title=Intel Architecure &#91;sic&#93; Programming and Information |publisher=Intel80386.com |date=January 13, 2004 |access-date=April 28, 2009}}</ref> although it could be significantly faster on optimized code and in tight loops, as many instructions could execute in [[clock cycles per instruction|2 clock cycles]] each. The 6&nbsp;MHz, 10&nbsp;MHz, and 12&nbsp;MHz models were reportedly measured to operate at 0.9&nbsp;MIPS, 1.5&nbsp;MIPS, and 2.66&nbsp;MIPS respectively.<ref>{{cite web |url=http://content.cdlib.org/ark:/13030/kt7h4nc9c2/?layout=metadata&brand=calisphere |title=80286 Microprocessor Package, 1982 |publisher=Content.cdlib.org |access-date=April 28, 2009 |archive-date=March 6, 2019 |archive-url=https://web.archive.org/web/20190306014151/http://content.cdlib.org/ark:/13030/kt7h4nc9c2/?layout=metadata&brand=calisphere |url-status=live }}</ref>

The later E-[[stepping level]] of the 80286 was free of the several significant [[erratum|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). This E-2 stepping part may have been available in later 1986.<ref name="Infoworld_1985_80286"/>

Intel [[second source]]d this microprocessor to [[Fujitsu|Fujitsu Limited]] in about 1985.<ref>Intel Corporation, "NewsBits: Second Source News", Solutions, January/February 1985, Page 1.</ref>
=== Variants ===

{| class="wikitable"
|-
! Model number !! Frequency !! Technology !! Process !! Package !! Date of release !! Price [[United States dollar|USD]]<ref group=list>In quantities of 100.</ref>
|-
| 80286-10<ref name="auto">Intel Corporation, "New Product Focus Components: 80286 Workhorses: Twice As Fast", Solutions, July/August 1985, Page 17.</ref> || 10 MHz || HMOS-III || [[1.5 μm process|1.5 μm]] || || July/August 1985 || $155
|-
| 80286-12<ref name="auto"/> || 12.5 MHz || HMOS-III || 1.5 μm || || July/August 1985 || $260
|-
| MG80286<ref>Intel Corporation, "New Product Focus Components: Highest Ranking 16-bit Microprocessor Meets Military Objectives", Solutions, September/October 1985, page 13.</ref> || || || || || September/October 1985 || $784
|-
| 80286<ref name="auto1">Ashborn, Jim; "Advanced Packaging: A Little Goes A Long Way", Intel Corporation, Solutions, January/February 1986, Page 2</ref> || || || || 68 Pin PGA<ref group=list>Sampling Q3 1985</ref> || January/February 1986 ||
|-
| 80286<ref name="auto1"/> || || || || 68 Pin PLCC<ref group=list>Sampling Q2 1986</ref> || January/February 1986 ||
|}

{{reflist|group=list}}

==Architecture==
[[File:Intel i80286 arch.svg|thumb|Simplified 80286 microarchitecture]]
[[File:Intel 80286 die.JPG|thumb|Intel 80286 die]]

Intel expected the 286 to be used primarily in industrial automation, transaction processing, and telecommunications, instead of in personal computers.<ref name="bloomberg19950305">{{cite news |last1=Gross |first1=Neil |url=https://www.bloomberg.com/news/articles/1995-03-05/the-technology-paradox |title=The Technology Paradox |date=1995-03-06 |work=Bloomberg |access-date=2020-03-19 |last2=Coy |first2=Peter |language=en}}</ref>

The CPU was designed for [[multi-user]] systems with [[computer multitasking|multitasking]] applications, including communications (such as automated [[private branch exchange|PBXs]]) and [[real-time computing|real-time]] [[process control]]. It had 134,000 [[transistor]]s and consisted of four independent units: the address unit, bus unit, instruction unit, and execution unit, organized into a [[loosely coupled]] (buffered) [[pipeline (computing)|pipeline]], just as in the 8086. It was produced in a 68-pin package, including PLCC ([[plastic leaded chip carrier]]), LCC ([[leadless chip carrier]]) and PGA ([[pin grid array]]) packages.<ref>{{cite web |title=Intel 80286 microprocessor family |publisher=CPU-World |url=http://www.cpu-world.com/CPUs/80286/ |access-date=May 19, 2012 |archive-date=March 31, 2012 |archive-url=https://web.archive.org/web/20120331094243/http://www.cpu-world.com/CPUs/80286/ |url-status=live }}</ref>

The performance increase of the 80286 over the 8086 (or 8088) could be more than 100% per [[clock cycle]] in many programs (i.e., a doubled performance at the same clock speed). This was a large increase, fully comparable to the speed improvements seven years later when the [[Intel 80486|i486]] (1989) or the original [[Pentium]] (1993) were introduced. This was partly due to the non-multiplexed address and data buses, but mainly to the fact that address calculations (such as [[addressing mode#Base plus index|base+index]]) were less expensive. They were performed by a dedicated unit in the 80286, while the older 8086 had to do effective address computation using its general [[arithmetic logic unit|ALU]], consuming several extra clock cycles in many cases. Also, the 80286 was more efficient in the prefetch of instructions, buffering, execution of jumps, and in complex [[microcode]]d numerical operations such as [[multiplication|MUL]]/[[division (mathematics)|DIV]] than its predecessor.<ref name=Bahadure2010>{{cite book |last=Bahadure |first=Nilesh B. |title=Microprocessors: 8086/8088, 80186/80286, 80386/80486 and the Pentium Family |publisher=PHI Learning Pvt. Ltd |year=2010 |isbn=978-8120339422 |chapter=15 Other 16-bit microprocessors 80186 and 80286 |pages=503–537 |chapter-url=https://books.google.com/books?id=XZzUyvghwnsC&pg=PA503 |access-date=October 11, 2016 |archive-date=February 27, 2017 |archive-url=https://web.archive.org/web/20170227204924/https://books.google.com/books?id=XZzUyvghwnsC&pg=PA503 |url-status=live }}</ref>

The 80286 included, in addition to all of the 8086 instructions, all of the new instructions of the 80186: ENTER, LEAVE, BOUND, INS, OUTS, PUSHA, POPA, PUSH immediate, IMUL immediate, and immediate shifts and rotates. The 80286 also added new instructions for protected mode: ARPL, CLTS, LAR, LGDT, LIDT, LLDT, LMSW, LSL, LTR, SGDT, SIDT, SLDT, SMSW, STR, VERR, and VERW. Some of the instructions for protected mode can (or must) be used in real mode to set up and switch to protected mode, and a few (such as SMSW and LMSW) are useful for real mode itself.

The Intel 80286 had a 24-bit address bus and as such had a 16&nbsp;[[megabyte|MB]] physical [[address space]], compared to the 1&nbsp;MB address space of prior x86 processors. It was the first x86 processor to support [[virtual memory]] supporting up to 1&nbsp;GB via segmentation.<ref>Intel Corporation, "New Product Focus Components: Highest Ranking 16-bit Microprocessor Meets Military Objectives", Solutions, September/October 1985, page 13</ref> However, memory cost and the initial rarity of software using the memory above 1&nbsp;MB meant that until late in its production, 80286 computers rarely shipped with more than 1&nbsp;MB of RAM.<ref name=Bahadure2010/> Additionally, there was a performance penalty involved in accessing extended memory from real mode as noted below.

==Features==
[[File:80286-processor-made-in-austria.jpg|thumb|upright|Siemens 80286 (10&nbsp;MHz version)]]
[[File:KL IBM 80286.jpg|thumb|upright|IBM 80286 (8&nbsp;MHz version)]]
[[File:Intersil MG80C286 10 883 1.jpg|thumb|upright|Intersil 80286 (10&nbsp;MHz version)]]

===Protected mode===
The 286 was the first of the x86 CPU family to support ''protected virtual-address mode'', commonly called "[[protected mode]]". In addition, it was the first commercially available microprocessor with on-chip [[memory management unit]] (MMU) capabilities (systems using the contemporaneous [[Motorola 68010]] and [[NS320xx]] could be equipped with an optional MMU controller). This would allow IBM compatibles to have advanced multitasking OSes for the first time and compete in the [[Unix]]-dominated<ref>{{Cite web |title=DOS Days - IBM OS/2 |url=https://dosdays.co.uk/topics/os2.php |access-date=2025-05-19 |website=dosdays.co.uk}}</ref> [[network server|server]]/[[workstation]] market.

Several additional instructions were introduced in the protected mode of 80286, which are helpful for multitasking operating systems.

Another important feature of 80286 is the prevention of unauthorized access. This is achieved by:
* Forming different segments for data, code, and stack, and preventing their overlapping.
* Assigning privilege levels to each segment. Segments with lower privilege levels cannot access segments with higher privilege levels.

In 80286 (and in its co-processor [[Intel 80287]]), arithmetic operations can be performed on the following different types of numbers:
* unsigned [[packed decimal]],
* unsigned binary,
* unsigned unpacked decimal,
* signed binary,
* [[floating-point number]]s (only with an [[80287]]).

By design, the 286 could not revert from protected mode to the basic 8086-compatible ''real address mode'' ("[[real mode]]") without a hardware-initiated reset. In the PC/AT introduced in 1984, IBM added external circuitry, as well as specialized code in the [[ROM BIOS]] and the [[8042]] keyboard 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. (The BIOS is necessarily involved because it obtains control directly whenever the CPU resets.) Though it worked correctly, the method imposed a huge performance penalty.

In theory, real-mode applications could be [[protected mode#Real mode application compatibility|directly executed in 16-bit protected mode]] if certain rules (newly proposed with the introduction of the 80286) were followed; however, as many DOS programs did not conform to those rules, protected mode was not widely used until the appearance of its successor, the [[32-bit computing|32-bit]] [[Intel 80386]], which was designed to go back and forth between modes easily and to provide an emulation of real mode within protected mode. When Intel designed the 286, it was not designed to be able to multitask real-mode applications; real mode was intended to be a simple way for a bootstrap loader to prepare the system and then switch to protected mode; essentially, in protected mode the 80286 was designed to be a new processor with many similarities to its predecessors, while real mode on the 80286 was offered for smaller-scale systems that could benefit from a more advanced version of the 80186 CPU core, with advantages such as higher clock rates, faster instruction execution (measured in clock cycles), and unmultiplexed buses, but not the 24-bit (16 MB) memory space.

To support protected mode, new instructions have been added: ARPL, VERR, VERW, LAR, LSL, SMSW, SGDT, SIDT, SLDT, STR, LMSW, LGDT, LIDT, LLDT, LTR, CLTS. There are also new exceptions (internal interrupts): invalid opcode, coprocessor not available, [[double fault]], coprocessor segment overrun, stack fault, segment overrun/general protection fault, and others only for protected mode.

===OS support===
The protected mode of the 80286 was not routinely utilized in PC applications until many years after its release, in part because of the high cost of adding extended memory to a PC, but also because of the need for software to support the large user base of 8086 PCs. 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. A [[DOS]] could utilize the additional RAM available in protected mode ([[extended memory]]) either via a [[BIOS]] call (INT 15h, AH=87h), as a [[RAM disk]], or as [[emulator|emulation]] of [[expanded memory]].<ref name=Bahadure2010/>

The difficulty lay in the incompatibility of older [[real-mode]] DOS programs with protected mode. They could not natively run in this new mode without significant modification. In protected mode, memory management and interrupt handling were done differently than in real mode. In addition, DOS programs typically would directly access data and code segments that did not belong to them, as real mode allowed them to do without restriction; in contrast, the design intent of protected mode was to prevent programs from accessing any segments other than their own unless special access was explicitly allowed. While it was possible to set up a protected-mode environment that allowed all programs access to all segments (by putting all segment descriptors into the [[Global Descriptor Table]] (GDT) and assigning them all the same privilege level), this undermined nearly all of the advantages of protected mode except the extended (24-bit) address space. The choice that OS developers faced was either to start from scratch and create an OS that would not run the vast majority of the old programs, or to come up with a version of DOS that was slow and ugly (i.e., ugly from an internal technical viewpoint) but would still run a majority of the old programs. Protected mode also did not provide a significant enough performance advantage over the 8086-compatible real mode to justify supporting its capabilities; actually, except for task switches when multitasking, it yielded a performance disadvantage, by slowing down many instructions through a litany of added privilege checks. In protected mode, registers were still 16-bit, and the programmer was still forced to use a memory map composed of 64&nbsp;kB segments, just like in real mode.<ref name=PCMAG1986>{{cite journal |author-last=Petzold |author-first=Charles |author-link=Charles Petzold |title=Obstacles to a grown up operating system |journal=PC Magazine |volume=5 |issue=11 |pages=170–74 |year=1986 |url=https://books.google.com/books?id=pDGnxFyejN4C&pg=PA170 |access-date=October 11, 2016 |archive-date=February 27, 2017 |archive-url=https://web.archive.org/web/20170227081813/https://books.google.com/books?id=pDGnxFyejN4C&pg=PA170 |url-status=live }}</ref>

Intel had not expected the lack of [[virtual machine]] support for 8086 software to be a problem, because it thought that new software using all of the 80286's capabilities would quickly appear. [[Bill Gates]] referred to the 80286 as a "brain-damaged" chip, because it cannot use virtual machines to multitask multiple [[MS-DOS]] applications<ref name="dewarsmosna1990">{{Cite book |last=Dewar |first=Robert B. K. |url=https://archive.org/details/microprocessorsp00robe/page/110/mode/1up?view=theater |title=Microprocessors: A Programmer's View |last2=Smosna |first2=Matthew |publisher=New York: McGraw-Hill |year=1990 |isbn=0-07-016638-2 |page=110 |url-access=registration}}</ref> with an operating system like [[Microsoft Windows]]. 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).
{{r|dewarsmosna1990}}

In January 1985, [[Digital Research]] previewed the [[Concurrent DOS 286]] 1.0 operating system developed in cooperation with Intel. The product would function strictly as an 80286 native-mode (i.e. protected-mode) operating system, allowing users to take full advantage of the protected mode to perform multi-user, multitasking operations while running 8086 emulation.<ref name="Infoworld_1985_Super"/><ref name="DRI_1986_FlexOS286"/><ref name="DRI_1986_CDOS68K-2"/> This worked on the B-1 prototype step of the chip, but Digital Research discovered problems with the emulation on the production level C-1 step in May, which would not allow Concurrent DOS 286 to run 8086 software in protected mode. The release of Concurrent DOS 286 was delayed until Intel would develop a new version of the chip.<ref name="Infoworld_1985_Super"/> In August, after extensive testing on E-1 step samples of the 80286, Digital Research acknowledged that Intel corrected all documented 286 errata, but said that there were still undocumented chip performance problems with the prerelease version of Concurrent DOS 286 running on the E-1 step. Intel said that the approach Digital Research wished to take in emulating 8086 software in protected mode differed from the original specifications. Nevertheless, in the E-2 step, they implemented minor changes in the [[microcode]] that would allow Digital Research to run emulation mode much faster.<ref name="Infoworld_1985_80286"/> 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.<ref>{{cite magazine|url=https://books.google.com/books?id=oi8EAAAAMBAJ&pg=PA12|title=IBM to use a DRI operating system|first1=Melissa |last1=Calvo |first2=Jim |last2=Forbes |magazine=InfoWorld|date=February 10, 1986|access-date=September 6, 2011|page=12|archive-date=April 21, 2019 |volume=8 |issue=8 |archive-url=https://archive.today/20190421185117/https://books.google.de/books?id=oi8EAAAAMBAJ&pg=PA12&redir_esc=y%23v=onepage&q&f=false|url-status=live}}</ref> 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.

Other operating systems that used the protected mode of the 286 were Microsoft [[Xenix]] (around 1984),<ref>{{cite web| url=http://www.tenox.net/docs/microsoft_xenix_30_286_press_release.pdf |title= Microsoft XENIX 3.0 Ready for 286 |archive-url=https://web.archive.org/web/20140107072346/http://www.tenox.net/docs/microsoft_xenix_30_286_press_release.pdf |archive-date=January 7, 2014}}</ref> [[Coherent (operating system)|Coherent]],<ref>{{cite web |url=http://textfiles.com/internet/FAQ/coherent.faq |title=An Introduction to Coherent: General Information FAQ for the Coherent Operating System |access-date=January 7, 2014 |archive-date=June 4, 2016 |archive-url=https://web.archive.org/web/20160604042547/http://textfiles.com/internet/FAQ/coherent.faq |url-status=live }}</ref> and [[Minix]].<ref>{{cite web| url=http://minix.net/minix/minix.html |title=MINIX INFORMATION SHEET | archive-url=https://web.archive.org/web/20140107074722/http://minix.net/minix/minix.html |archive-date=January 7, 2014}}</ref> These were less hindered by the limitations of the 80286 protected mode because they did not aim to run MS-DOS applications or other real-mode programs.

When designing the 80386 Intel engineers were aware of, and agreed with, the 80286's poor reputation.<ref name="inteloh20081202">{{Cite interview |last=Crawford |first=John |interviewer=Jim Jarrett |title=Intel 386 Microprocessor Design and Development Oral History Panel |last2=Hill |first2=Gene |last3=Leukhardt |first3=Jill |last4=Prak |first4=Jan Willem |last5=Slager |first5=Jim |url=https://archive.computerhistory.org/resources/access/text/2015/06/102702019-05-01-acc.pdf |access-date=2025-05-15 |publisher=Computer History Museum |place=Mountain View, California |language=en-US}}</ref> They enhanced the 80386's protected mode to address more memory, and also added the separate [[virtual 8086 mode]], a mode within protected mode with much better MS-DOS compatibility.<ref>{{cite magazine |first=Charles |last=Petzold |author-link=Charles Petzold |title=Intel's 32-bit Wonder: The 80386 Microprocessor |magazine=[[PC Magazine]] |date=November 25, 1986 |pages=150–152}}</ref>

==Support components==
[[File:Siemens SAB8228x.jpg|thumb|Siemens SAB82284, SAB82288, and SAB82289 (at [[Deutsches Museum]])]]
This is a list of bus interface components that connect to an Intel 80286 microprocessor.

* 82230/82231 High Integration AT-Compatible Chip Set – The 82230 covers this combination of chips: 82C284 clock, 82288 bus controller, and dual 8259A interrupt controllers among other components. The 82231 covers this combination of chips: 8254 interrupt timer, 74LS612 memory mapper and dual 8237A DMA controller among other components. They were available by second-sourced with Zymos Corp. Both set are available USD $60 for 10 MHz version and USD $90 for 12 MHz version in quantities of 100.<ref>Ormsby, John, Editor, "New Product Focus: Components: Intel's 82X3X Chip-set Handles Logic Functions That Once Required The Services Of Sources Of Chips", Intel Corporation, Microcomputer Solutions, January/February 1988, page 13</ref>
* 82258 Advanced Direct Memory Access Controller – Transfer rate of 8MB per second, supports up to 32 subchannels, mask and compare, verify, translation, and assembly/disassembly operation that are being processed simultaneously. It also supports a 16MB addressing range. These were available for USD $170 in quantities of 100.<ref>Intel Corporation, "New Product Focus Components: The 82258 ADMA Boost iAPX 286 Family Performance", ''Solutions'', November/December 1984, Page 14.</ref>
* 82C284 Clock Generator and Driver – Intel second sourced this 82284 version to Fujitsu Limited around 1985.<ref>Intel Corporation, "NewsBits: Second Source News", ''Solutions'', January/February 1985, Page 1</ref> The Intel branded chipset was available in 20-pin [[Chip_carrier#Plastic-leaded_chip_carrier|PLCC]] in sampling at first quarter 1986.<ref name="auto1"/>
* [[Intel 82288|82288]] Bus Controller
* 82289 [[Arbiter (electronics)|Arbiter]]

==See also==
* [[U80601]] – Almost identical copy of the 80286 manufactured 1989/1990 in [[East Germany]]. In the [[Soviet Union]] a clone of the 80286 was [[Soviet integrated circuit designation|designated]] [[KR1847VM286]] ({{langx|ru|КР1847ВМ286|italic=yes}}).<ref name=cpuworld>{{cite web
| title=Soviet microprocessors, microcontrollers, FPU chips and their western analogs
| publisher=CPU-world
| url=https://www.cpu-world.com/info/exUSSR-chips.html
| access-date=March 24, 2016
| archive-date=February 9, 2017
| archive-url=https://web.archive.org/web/20170209223725/http://www.cpu-world.com/info/exUSSR-chips.html
| url-status=live
}}</ref>
* [[iAPX]], for the iAPX name
* [[LOADALL]] – Undocumented 80286/80386 instruction that could be used to gain access to all available memory in real mode.
* [[Windows 2.1x#Windows.2F286|Windows/286]]

==References==
{{Reflist|refs=
<ref name="Infoworld_1985_Super">{{cite magazine |first=Edward |last=Foster |title=Super DOS awaits new 80286 – Concurrent DOS 286 – delayed until Intel upgrades chip – offers Xenix's power and IBM PC compatibility |publisher=[[InfoWorld Media Group]] |magazine=[[InfoWorld]] |volume=7 |issue=19 |date=May 13, 1985 |issn=0199-6649 |pages=17–18 |url=https://books.google.com/books?id=2y4EAAAAMBAJ&pg=PA17 |access-date=October 11, 2016 |archive-date=February 27, 2017 |archive-url=https://web.archive.org/web/20170227082258/https://books.google.com/books?id=2y4EAAAAMBAJ&pg=PA17 |url-status=live }}</ref>
<ref name="Infoworld_1985_80286">{{cite magazine |first=Edward |last=Foster |title=Intel shows new 80286 chip – Future of DRI's Concurrent DOS 286 still unclear after processor fixed |publisher=[[InfoWorld Media Group]] |magazine=[[InfoWorld]] |volume=7 |issue=34 |date=August 26, 1985 |issn=0199-6649 |page=21 |url=https://books.google.com/books?id=_y4EAAAAMBAJ&pg=PA21 |access-date=December 25, 2021 |archive-date=January 25, 2014 |archive-url=https://web.archive.org/web/20140125074700/http://books.google.com/books?id=_y4EAAAAMBAJ&pg=PA21 |url-status=live }}</ref>
<ref name="DRI_1986_FlexOS286">{{cite book |title=FlexOS Supplement for Intel iAPX 286-based Computers |publisher=[[Digital Research, Inc.]] |date=November 1986 |edition=1 |version=1.3 |url=http://www.bitsavers.org/pdf/digitalResearch/flexos/FlexOS_Suppliment_For_iAPX286_Computers_Nov86.pdf |access-date=August 14, 2018 |archive-date=April 21, 2019 |archive-url=https://web.archive.org/web/20190421183934/http://www.bitsavers.org/pdf/digitalResearch/flexos/FlexOS_Suppliment_For_iAPX286_Computers_Nov86.pdf |url-status=live }}</ref>
<ref name="DRI_1986_CDOS68K-2">{{cite web |title=Concurrent DOS 68K 1.2 - Developer Kit for Motorola VME/10 - Disk 2 |date=August 6, 1986 |orig-year=1986-04-08 |url=http://www.cpm.z80.de/download/cdos2.zip |access-date=September 13, 2018 |archive-date=April 3, 2019 |archive-url=https://web.archive.org/web/20190403010111/http://www.cpm.z80.de/download/cdos2.zip |url-status=live }} (NB. This package also includes some header files from [[Concurrent DOS 286]], including STRUCT.H explicitly mentioning [[LOADALL]] for "8086 emulation".)</ref>
}}

==External links==
{{Commons category}}
* [http://datasheets.chipdb.org/Intel/x86/286/datashts Intel Datasheets]
* [http://bitsavers.org/components/intel/80286/210498-005_80286_and_80287_Programmers_Reference_Manual_1987.pdf Intel 80286 and 80287 Programmer's Reference Manual] at bitsavers.org
* [http://www.ragestorm.net/downloads/286intel.txt Intel 80286 Programmer's Reference Manual 1987 (txt)]. Hint: use e.g. ''Hebrew (IBM-862)'' encoding. <!-- This is not perfect, but better than ISO8859-1 or UTF-8. -->
* [https://web.archive.org/web/20111011185133/http://tuxmobil.org/286_mobile.html Linux on 286 laptops and notebooks]
* [http://www.cpu-collection.de/?tn=1&l0=cl&l1=80286 Intel 80286 images and descriptions at cpu-collection.de]
* [https://web.archive.org/web/20110614122946/http://www.cpu-info.com/index2.php?mainid=286 CPU-INFO: 80286, in-depth processor history]
* [https://web.archive.org/web/20110614123051/http://www.cpu-info.com/index2.php?mainid=Collection&ID=80286&type=cpu Overview of all 286 compatible chips]
* [https://www.pcjs.org/pubs/pc/reference/intel/80286/ Intel 80286 CPU Information, including chip errata and undocumented behaviour]
* [https://archive.org/details/bitsavers_intel80286areReferenceManual1987_14090554/mode/2up Intel 80286 Hardware Reference Manual]

{{Intel processors|discontinued}}
{{Authority control}}

[[Category:Intel x86 microprocessors|80286]]
[[Category:16-bit microprocessors]]
[[Category:Computer-related introductions in 1982]]
[[Category:X86 microarchitectures]]