The Most Popular Operating System in the World

What is the world’s most widely used operating system? It’s not Windows, Unix or Linux, but ITRON, a Japanese real-time kernel for small-scale embedded systems. ITRON runs on mobile phones, digital cameras, CD players and countless other electronic devices.

ITRON emerged as an ambitious Japanese initiative known as The Real-time Operating system Nucleus (TRON). Launched in 1984, TRON was designed to replace disparate computer systems with a unified, open architecture for a “total computer environment.”

Its ultimate goal was to create “highly functionally distributed systems” in which all system components are connected to a real-time network. Professor Ken Sakamura, spiritual father of TRON, conceived the project as a social infrastructure akin to the electrical power grid or water supply system.

Now, the T-Engine Forum, an offshoot of the TRON project with more than 250 member companies, has been working to create a standardized development environment for embedded applications based on ITRON. Vendors of proprietary solutions are worried — or at least should be.

ITRON Is First

ITRON, the first in a series of open-source specifications for the TRON architecture, answered a pressing need for Japan’s electronics firms, which traditionally have written their own software for embedded systems, a time-consuming and cumbersome process that often results in a plethora of different and incompatible systems.

The ITRON specification is a standard real-time OS kernel that can be tailored to any embedded system. ITRON already has been ported to a wide range of microprocessor architectures and has quickly become Japan’s de facto standard for embedded systems. Today, the specification is used in an estimated 3 billion microprocessors.

ITRON has been followed by several other specifications — among them Business TRON (BTRON), a multilingual, ubiquitous computing environment with a programmable GUI, and Communications and Central TRON (CTRON), a real-time, multitasking operating system akin to Unix.

Japanese telecom giant NTT has embraced CTRON and made it the de facto standard in Japan’s telecom industry.

Impact Deferred

The TRON Project is not new; in fact, it was poised to its mark more than a decade ago, in Japan’s PC industry, but the U.S. government intervened. In 1989, Japanese electronics giant Matsushita introduced a BTRON PC, a machine that stunned the industry with its advanced capabilities. The BTRON PC had an 80286 Intel chip running at 8 MHz and a mere 2 MB of memory, but it could display moving video in color in a separate window. Also, it had a dual-booting system that could run both the BTRON OS and MS-DOS.

When the Japanese government announced it would install BTRON PC in Japanese schools, the U.S. government objected. It called the Japanese initiative “actual and potential market intervention” and threatened the move with sanctions. The Japanese, dependent on the U.S. export market, quickly dropped the plan. The U.S. government later withdrew its threat, but the damage had already been done. Nearly all Japanese companies involved in TRON-related activities had canceled their projects.

Nevertheless, ITRON survived, and today it powers millions of Japanese gadgets, household appliances, automobile electronics, robots and even satellites. ITRON is also widely used in factory automation systems in China. Industry insiders claim it is the number one OS for embedded chips in both Japan and the United States.

ITRON Survival

Earlier this year, U.S.-based Accelerated Technology, the embedded systems division of Mentor Graphics, was appointed as the North American Liaison Office of the TRON Association. But can ITRON survive the growing popularity of Linux and its real-time version, RTLinux?

Steven Searle, who worked on developing TRON’s multilingual environment, argues that ITRON has several advantages over real-time versions of Linux. “TRON is an RTOS; Linux isn’t,” Searle told LinuxInsider, adding that ITRON has a smaller footprint and superior real-time performance.

“RTLinux switches tasks in milliseconds, while ITRON switches tasks in microseconds,” he said. “RTLinux’ footprint is measured in megabytes; ITRON is measured in kilobytes.”

Recent developments suggest ITRON and Linux are finding a middle ground. The T-Engine Forum, which formed an alliance with Linux developer MontaVista earlier this year, aims to standardize embedded systems at the CPU level, incorporating TRON’s real-time OS, security architecture (eTRON), middleware modules and MontaVista Linux.

The MontaVista Partnership

MontaVista is actually helping to create a non-native kernel extension of TRON called T-Linux — an environment for running middleware. T-Engine and Linux will form a base for developing application software that will include the eTRON chip, an encryption device that offers secure data transfer across wireless networks and the Internet.

“T-Engine offers several benefits, among them new options for CPU architecture migration and more flexible commercial-licensing terms, in that T-Engine is not subject to the software patent,” Bill Weinberg, director of strategy and evangelism at MontaVista, told LinuxInsider.

“At some point in the future,” said Weinberg, “the T-Linux architecture is intended to support execution of both legacy ITRON code over T-Engine and native Linux code on the native Linux portion.”

Linux Alliance

This alliance between TRON and Linux could put more pressure on vendors of proprietary embedded software. Proprietary software is costly — vendors usually charge royalties for each microprocessor running the software — and licensing terms are often restrictive. Moreover, nearly all of the giants in the consumer electronics industry are rallying around open-source solutions.

In late September, Microsoft surprised the industry by joining the T-Engine Forum. Microsoft intends to work with the Forum to establish specifications for an environment in which the T-Kernel and Windows CE can coexist on the T-Engine hardware reference platform.

Microsoft will continue to develop its own OS, but the company hopes T-Engine developers will be attracted to Windows CE’s user interfaces. The company will demonstrate prototypes derived from the joint effort at December’s Tokyo TronShow.

Microsoft’s decision to join the T-Engine Forum is not without irony. The company was the main beneficiary of U.S. government actions against the TRON project in 1989. Tom Robertson, Microsoft’s Tokyo-based director for government affairs in Asia, is a former official of the United States Trade Representative office that issued the threats against the Japanese government.


  • Is there data ranking the most popular OSes that you can share with us? Or, how did you determine that ITRON was the most popular? And, does that mean "used in the most devices," or "used by the most developers?"
    Thanks for these clarifications.

  • Wow, and to think Intel is just thinking about a processor that can boot more than one operating system at once. You’d think they could have learned from these guys. It should’ve been a small step from one OS at a time, to more than one especially with the popularity of the software packages that allow it.

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