Intel 80186

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Intel 80186
KL Intel i186.jpg
An Intel A80186 processor with a gray heat spreader.
General information
DiscontinuedSeptember 28, 2007 [1]
Common manufacturer(s)
Max. CPU clock rate 6 MHz to 25 MHz
FSB speeds6 MHz to 25 MHz
Data width16 bits
Address width20 bits
Architecture and classification
Min. feature size 3 µm [3]
Instruction set x86-16
Physical specifications
  • 55,000
Co-processor 8087 and later, 80187 (for 80186 only)
  • 68-pin PLCC
    68-pin LCC
    100-pin PQFP (Engineering Sample Only)
    68-pin PGA
Products, models, variants
Variant(s) Intel 80188
Predecessor Intel 8088
Successor Intel 80386 (The 80286 was also introduced in early 1982, and thus contemporary with the 80186)
A greatly simplified block diagram of the 80186 architecture Intel 80186 80188 arch.svg
A greatly simplified block diagram of the 80186 architecture
Die of Intel 80186 Intel 80186 die.JPG
Die of Intel 80186

The Intel 80186, also known as the iAPX 186, [4] or just 186, is a microprocessor and microcontroller introduced in 1982. It was based on the Intel 8086 and, like it, had a 16-bit external data bus multiplexed with a 20-bit address bus. The 80188 variant, with an 8-bit external data bus was also available.



The 80186 series was generally intended for embedded systems, as microcontrollers with external memory. Therefore, to reduce the number of integrated circuits required, it included features such as clock generator, interrupt controller, timers, wait state generator, DMA channels, and external chip select lines.

The initial clock rate of the 80186 was 6  MHz, but due to more hardware available for the microcode to use, especially for address calculation, many individual instructions ran faster than on an 8086 at the same clock frequency. For instance, the common register+immediate [lower-alpha 1] addressing mode was significantly faster than on the 8086, especially when a memory location was both (one of) the operand(s) and the destination. Multiply and divide also showed great improvement being several times as fast as on the original 8086 and multi-bit shifts were done almost four times as quickly as in the 8086.

A few new instructions were introduced with the 80186 (referred to as the 8086-2 instruction set in some datasheets): enter/leave (replacing several instructions when handling stack frames), pusha/popa (push/pop all general registers), bound (check array index against bounds), and ins/outs (input/output of string). A useful immediate mode was added for the push, imul, and multi-bit shift instructions. These instructions were also included in the contemporary 80286 and in successor chips. (The instruction set of the 80286 is superset of the 80186's, plus new instructions for Protected mode.)

Die of Intel 80C186. Intel 80C186 die.JPG
Die of Intel 80C186.

The (redesigned) CMOS version, 80C186, introduced DRAM refresh, a power-save mode, and a direct interface to the 80C187 floating point numeric coprocessor.


In personal computers

The 80186 would have been a natural successor to the 8086 in personal computers.[ citation needed ] However, because its integrated hardware was incompatible with the hardware used in the original IBM PC, the 80286 was used as the successor instead, in the IBM PC/AT.

A few notable personal computers used the 80186: the Australian Dulmont Magnum laptop, one of the first laptops; the Wang Office Assistant, marketed as a PC-like stand-alone word processor; the Mindset; the Siemens PC-D  [ de ] (not 100% IBM PC compatible but using MS-DOS 2.11); the Compis (a Swedish school computer); the French SMT-Goupil G4; the RM Nimbus (a British school computer); the Unisys ICON (a Canadian school computer); ORB Computer by ABS; the HP 100LX, HP 200LX, HP 1000CX, and HP OmniGo 700LX; the Tandy 2000 desktop (a somewhat PC-compatible workstation with sharp graphics for its day); the Telex 1260 (a desktop PC-XT compatible); the Philips :YES; the Nokia MikroMikko 2. Acorn created a plug-in for the BBC Master range of computers containing an 80186-10 with 512 KB of RAM, the BBC Master 512 system.

In addition to the above examples of stand-alone implementations of the 80186 for personal computers, there was at least one example of an "add-in" accelerator card implementation: the Orchid Technology PC Turbo 186, [5] released in 1985. It was intended for use with the original Intel 8088-based IBM PC (Model 5150).

Other devices

The Intel 80186 is intended to be embedded in electronic devices that are not primarily computers. For example:

In May 2006, Intel announced that production of the 186 would cease at the end of September 2007. [9] Pin- and instruction-compatible replacements might still be manufactured by various third party sources, [10] and FPGA versions are publicly available. [11]

See also


  1. In fact, all variants, including reg+reg and reg+reg+immediate were faster.

Related Research Articles

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Intel 80188

The Intel 80188 microprocessor was a variant of the Intel 80186. The 80188 had an 8-bit external data bus instead of the 16-bit bus of the 80186; this made it less expensive to connect to peripherals. The 16-bit registers and the one megabyte address range were unchanged, however. It had a throughput of 1 million instructions per second.

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The iAPX 432 is a discontinued computer architecture introduced in 1981. It was Intel's first 32-bit processor design. The main processor of the architecture, the general data processor, is implemented as a set of two separate integrated circuits, due to technical limitations at the time. Although some early 8086, 80186 and 80286-based systems and manuals also used the iAPX prefix for marketing reasons, the iAPX 432 and the 8086 processor lines are completely separate designs with completely different instruction sets.

Intel i960

Intel's i960 was a RISC-based microprocessor design that became popular during the early 1990s as an embedded microcontroller. It became a best-selling CPU in that segment, along with the competing AMD 29000. In spite of its success, Intel stopped marketing the i960 in the late 1990s, as a result of a settlement with DEC whereby Intel received the rights to produce the StrongARM CPU. The processor continues to be used for a few military applications.


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In computer architecture, 16-bit integers, memory addresses, or other data units are those that are 16 bits wide. Also, 16-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 16-bit microcomputers are computers in which 16-bit microprocessors were the norm.

In marketing, iAPX was a short lived designation used for several Intel microprocessors, including some 8086 family processors. Not being a simple initialism seems to have confused even Intel's technical writers as can be seen in their iAPX-88 Book where the asterisked expansion shows iAPX to mean Intel Advanced Processor System.


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  5. Adding Spunk to the IBM PC in InfoWorld, May 20, 1985
  7. Brear, Scott (21 January 1985). "Cycle of change speeds up". Computerworld. IDG Enterprise. 19 (3): ID/15. ISSN   0010-4841.
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