Intel 80186


The Intel 80186, also known as the iAPX 186, 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. It was also available as the 80188, with an 8-bit external data bus.

Description

Features and performance

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 addressing mode was significantly faster than on the 8086, especially when a memory location was both operand 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 : enter/leave, pusha/popa, bound, and ins/outs. 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 CMOS version, 80C186, introduced DRAM refresh, a power-save mode, and a direct interface to the 8087 or 80187 floating point numeric coprocessor.

Uses

In personal computers

The 80186 would have been a natural successor to the 8086 in personal computers. 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 ; the Compis ; the French SMT-Goupil G4; the RM Nimbus ; the Unisys ICON ; ORB Computer by ABS; the HP 100LX, HP 200LX, HP 1000CX, and HP OmniGo 700LX; the Tandy 2000 desktop ; the Telex 1260 ; the ; 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, released in 1985. It was intended for use with the original Intel 8088-based IBM PC.

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. Pin- and instruction-compatible replacements might still be manufactured by various third party sources, and FPGA versions are publicly available.