Intel 80386EX
An embedded 386 variant used in satellites and many commercial devices.
The Intel 80386EX, or i386EX, is a version of the Intel 386 chip tailored for embedded uses. It hit the market in August 1994 and proved quite popular, finding its way into several satellites and microsatellites in orbit. Before this chip, Intel’s go-to embedded x86 processor was the 80186. Like that earlier model, the 80386EX packs in built-in peripherals such as a timer, DMA controller, and interrupt controller, which cuts down the number of extra parts needed for a system. A key difference, though, is that the 80386EX’s onboard peripherals work with standard PC/AT components, whereas the 80186’s did not. Intel didn’t release another integrated x86 processor until 2007, when it announced the Tolapai (EP80579) based on the Enhanced Pentium M. Samples of the Intel386 EX were planned for April 1994, with full production in the third quarter, priced at US$39 in quantities of 5,000.
This chip is a variant of the 80386SX built for embedded systems. It uses 26-bit memory addressing, giving access to up to 64 MiB of DRAM, and has a 16-bit data bus—which limits speed but keeps system costs down. Its core is static, meaning it can run as slowly as needed (and thus very power-efficiently), all the way down to a complete halt. It also supports System Management Mode. On-chip peripherals include clock and power management, timers and counters, a watchdog timer, serial I/O units (both synchronous and asynchronous), parallel I/O, DMA, RAM refresh, and JTAG test logic. The 80386EX was significantly more successful than the earlier 80376. Beyond satellites, it was used in NASA’s FlightLinux project, the USRobotics Courier I modem V.everything, Ericsson R290 and Globalstar/Qualcomm GSP-1600 satellite phones, many older Garmin GPS units (like the GPS 48, II, III, and 12), Akai S5000 and S6000 digital samplers, the Nokia 9000 Communicator, Swarco ITC-2 traffic light controllers, Sperry Marine Navigat X MKI/MKII gyro compasses, Gallagher/Cardax FT 3000 systems, Videokê/intermagic karaoke machines, and Ziton ZP3 fire alarm control panels.
- Introduced
- August 1994
- Variant of
- 80386SX intended for embedded systems
- Memory addressing
- 26-bit, up to 64 MiB of DRAM
- Data bus
- 16-bit
- Core type
- Static core (may run as slowly as desired, down to full halt)
- On-chip peripherals
- clock and power management, timers/counters, watchdog timer, serial I/O (synchronous and asynchronous), parallel I/O, DMA, RAM refresh, JTAG test logic
- Sample price
- US$39 in 5,000-piece quantities (planned for Q3 1994 production)
Lore & Background
The Intel 80386EX was a variant of the 80386SX intended for embedded systems, introduced in August 1994. It succeeded Intel's previous x86 embedded CPU, the Intel 80186. Like the 80186, the 80386EX integrates several peripherals including a timer, DMA controller, and interrupt controller, which vastly reduces the number of system components required for implementing a 80386EX-based system. Unlike the 80186, the peripherals of the 80386EX are compatible with standard PC/AT components.
The processor features a static core, meaning it may run as slowly (and thus power efficiently) as desired, down to full halt. It supports System Management Mode and includes on-chip peripherals such as clock and power management, timers/counters, a watchdog timer, serial I/O units (synchronous and asynchronous), parallel I/O, DMA, RAM refresh, and JTAG test logic. It uses 26-bit memory addressing for up to 64 MiB of DRAM and a 16-bit data bus, which limits performance but reduces system cost.
The 80386EX was significantly more successful than the earlier 80376. Intel did not manufacture another integrated x86 processor until 2007, when it confirmed the Enhanced Pentium M-based Tolapai (EP80579).
Reader's Guide
The Intel 80386EX holds significance as a highly successful embedded x86 processor that bridged the gap between general-purpose PC architecture and low-power, integrated embedded systems. Its integration of peripherals compatible with standard PC/AT components reduced system complexity and cost, making it attractive for a wide range of applications. The processor's static core allowed extreme power savings by running at arbitrarily low clock speeds or halting completely, which was critical for battery-powered and thermally constrained devices.
Its market success is evidenced by its use in diverse products: from USRobotics Courier I modems and Ericsson R290 satellite phones to Nokia 9000 Communicator phones, Akai S5000/S6000 digital samplers, and many older Garmin GPS units. It also found use in industrial and infrastructure equipment such as Swarco ITC-2 traffic light controllers, Sperry Marine Navigat X gyro compasses, and Ziton ZP3 fire alarm control panels. Notably, it was used aboard several orbiting satellites and microsatellites, as well as in NASA's FlightLinux project. The 80386EX remained Intel's only integrated x86 processor for over a decade until the Tolapai in 2007.
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