Intel 80186

Lore & Background

The 80186 was introduced in 1982 as a microprocessor and microcontroller. It was based on the Intel 8086 but included integrated hardware such as a clock generator, interrupt controller, timers, wait state generator, DMA channels, and external chip select lines, reducing the chip count in systems. The initial clock rate was 6 MHz, but due to more hardware available for microcode, many instructions completed in fewer clock cycles than on an 8086 at the same frequency. For example, register+immediate addressing was significantly faster, multiply and divide were several times faster, and multi-bit shifts were almost four times quicker. New instructions were introduced: enter/leave, pusha/popa, bound, and ins/outs, along with immediate modes for push, imul, and multi-bit shifts. These instructions were also included in the 80286 and successor chips.

CMOS variants followed, including the 80C186, which added DRAM refresh, a power-save mode, and a direct interface to the 80C187 floating-point coprocessor. Intel second-sourced the 80186 to Fujitsu Limited around 1985. Packages included 68-pin PLCC and PGA, with sampling in the third quarter of 1985. The 12.5 MHz Intel 80186-12 used the 1.5 μm HMOS-III process and cost US$36 in quantities of 100. The 12.5 MHz Intel 80C186 used CHMOS III-E technology, drawing about 90 mA under normal load and 32 mA in power-save mode, and was available in 68-pin PLCC, CPGA, or CLCC packages. Military versions (M80C186) were available in 10 and 12 MHz versions, meeting MIL-STD-883 Rev. C and MIL-STD-1553 bus standards, with the 12 MHz version consuming about 100 mA. The 10 MHz M80C186 PGA version cost US$378 in 100-unit quantities.

Later variants included the fully static 80C186EB (1 μm CHMOS IV, 3- and 5-volt versions, 84-lead PLCC and 80-lead EIAJ QFP, US$16.95 in 1,000-unit quantities), the 80C186EC (4 DMA channels, 2 interrupt controllers, 22 I/O, two serial channels, 4 timers, 5-volt only, US$17.70 in 1,000-unit quantities), and the 80C186XL (up to 20 MHz, 25% higher performance and 50% lower power consumption than existing CMOS 80C186, using 1 μm CHMOS). The 80C186EA and 80C186XL were both available for US$11.80 in 1,000-unit quantities. The 80188 variant, with an 8-bit external data bus, was also available, offering lower cost connection to peripherals while retaining 16-bit registers and the one megabyte address range. It had a throughput of 1 million instructions per second. The 80C188EB was a fully static design in 3- and 5-volt versions, costing US$15.15 in 1,000-unit quantities.

Reader's Guide

The 80186's significance lies in its integration of system-level components onto a single chip, making it a precursor to modern microcontrollers. However, because its integrated hardware was incompatible with the support chips IBM chose for the 8088-based IBM PC, the chip did not see wide success in the personal computer market. IBM instead used the 80286 for the IBM PC/AT. Despite this, several notable personal computers used the 80186, including the Dulmont Magnum laptop, the Tandy 2000, the RM Nimbus PC-186, the Compis, and the HP 100LX/200LX series. It also appeared in add-in accelerator cards such as the BBC Master 512 and the Orchid Technology PC Turbo 186. Beyond personal computers, the 80186 and 80188 were embedded in many non-computer devices: the Microtek 8086 in-circuit emulator, the Intel 14.4EX modem (using a 16 MHz 80188 for forward error correction and echo cancellation), the SatisFAXtion board, the IBM 7171 protocol converter, the Tektronix 2246 oscilloscope, and Digital Equipment Corporation's DECtalk speech synthesizer. Production of the 80186 and 80188 ceased at the end of September 2007, though pin- and instruction-compatible replacements may still be manufactured by third parties, and FPGA versions are publicly available.

Did You Know?

• The 80186 introduced instructions such as enter/leave, pusha/popa, bound, and ins/outs, which were also included in the 80286 and later chips.
• The 12.5 MHz Intel 80C186 version used CHMOS III-E technology and drew only 32 mA in power-save mode.
• The 80188 variant had an 8-bit external data bus but retained 16-bit registers and a one megabyte address range.
• The 80186 was used in the IBM 7171 protocol converter to make ASCII terminals appear as IBM 3270 terminals.