TRON (The Real-time Operating system Nucleus) is an open architecture real-time operating system kernel design. The project was started by Ken Sakamura of the University of Tokyo in 1984. The project's goal is to create an ideal computer architecture and network, to provide for all of society's needs. For different scenarios, the need for different OS kernels was identified. (See, for example, papers written in English in TRON Project 1988 )

The Industrial TRON (ITRON) derivative was one of the world's most used operating systems in 2003, being present in billions of electronic devices such as mobile phones, appliances and even cars. Although mainly used by Japanese companies, it garnered interest worldwide. However, a dearth of quality English documentation was said to hinder its broader adoption. The situation has improved since TRON Forum has taken over the activities to support TRON Project since 2015. (See the specification page that lists many English documents. )

The focus of these activities was a non-profit organization called TRON Association which acted as the communication hub for the parties concerned with the development of ITRON specification OS and its users in many fields including home electronics, smart house industry, etc.

In 2002, T-Engine Forum was formed to provide an open source RTOS implementation that supersedes the ITRON specification OS, and provides binary compatibility additionally. The new RTOS was T-Kernel. The activities of TRON Association to support TRON Project were taken over by T-Engine Forum in 2010. In 2015, T-Engine Forum changed its name into TRON Forum.

Today, ITRON specification OS and T-Kernel RTOS are supported by popular Secure Socket Layer (SSL) and Transport Layer Security (TLS) libraries such as wolfSSL.

In 1984, the TRON project was officially launched. In 1985, NEC announced the first ITRON implementation based on the ITRON/86 specification. In 1986, the TRON Kyogikai (unincorporated TRON Association) was established, Hitachi announced its ITRON implementation based on the ITRON/68K specification, and the first TRON project symposium is held. In 1987, Fujitsu announced an ITRON implementation based on the ITRON/MMU specification. Mitsubishi Electric announced an ITRON implementation based on the ITRON/32 specification, and Hitachi introduced the Gmicro/200 32-bit microprocessor based on the TRON VLSI CPU specification.

In 1988, BTRON computer prototypes were being tested in various schools across Japan as the planned standardized computer for education. The project was organized by both the Ministry of International Trade and Industry and the Ministry of Education. However, Scott Callon of Stanford University writes that the project ran into some issues, such as BTRON being incompatible with existing DOS-based PCs and software. At the time NEC controlled 80–90% of the education market with DOS infrastructure, so adopting BTRON would have meant getting rid of all existing infrastructure. The existing incompatible PC software had also been personally written by school personnel, who opposed BTRON for this incompatibility with their earlier projects. There was also no software yet for the brand new computer. The project was additionally at least a year behind schedule and didn't perform better than earlier systems although that had been promised, which was possibly affected by the OS having been made by a firm that hadn't written one before. Because of these reasons, at the end of 1988 the Ministry of Education decided that it would not support the project unless BTRON was also made compatible with DOS. The Ministry of International Trade and Industry had hoped to avoid supporting NEC's domination of the PC market with DOS.

BTRON integration with NEC DOS architecture was difficult but possible with negotiation. In April 1989 the Office of the U.S. Trade Representative issued a preliminary report accusing BTRON of being a trade barrier, as it only functioned in Japan, and asked the Japanese government not to make it standard in schools. TRON was included along with rice, semiconductors, and telecommunications equipment in a list of items targeted by Super-301 (complete stop of import based on section 301 of the Omnibus Trade and Competitiveness Act of 1988). It was removed from the list after the USTR inspection team visited the TRON Association in May. In June the Japanese government expressed their regret at U.S. intervention but accepted this request not to make it standard in schools, thus ending the BTRON project. Callon opines that the project had nevertheless run into such difficulties that the U.S. intervention allowed the government to save face from cancelling the project.