JavaOS

JavaOS is predominantly a U/SIM-Card operating system based on a Java virtual machine and running applications on behalf of operators and security services. It was originally developed by Sun Microsystems. Unlike Windows, macOS, Unix, or Unix-like systems which are primarily written in the C programming language, JavaOS is primarily written in Java. It is now considered a legacy system.
History.
The Java programming language was introduced by Sun in May 1995. Jim Mitchell and Peter Madany at JavaSoft designed a new operating system, codenamed Kona, written completely in Java. In March 1996, Tom Saulpaugh joined the now seven-person Kona team to design an I/O architecture, having come from Apple as Mac OS engineer since June 1985 and co-architect of Copland.
JavaOS was first evangelized in a "Byte" article. In 1996, JavaSoft's official product announcement described the compact OS designed to run "in anything from net computers to pagers". In early 1997, JavaSoft transferred JavaOS to SunSoft. In late 1997, Bob Rodriguez led the team to collaborate with IBM who then marketed the platform, accelerated development, and made significant key architectural contributions to the next release of JavaOS, eventually renamed JavaOS for Business. IBM indicated its focus was more on network computer thin clients, specifically to replace traditional "green screen" and UNIX terminals, and to implement single application clients. The Chorus distributed real-time operating system was purchased for its microkernel technology.
JavaSoft has granted licenses to more than 25 manufacturers, including Oracle Corp, Acer Inc., Xerox, Toshiba Corp, and Nokia. IBM and Sun announced the cooperation for JavaOS for Business at the end of March 1998.
In 1999, Sun and IBM announced the discontinuation of the JavaOS product. As early as 2003, Sun materials referred to JavaOS as a "legacy technology", recommending migration to Java ME, leaving the choice of specific OS and Java environment to the implementer.
Overview.
JavaOS is based on a hardware architecture native microkernel, running on platforms including ARM, PowerPC, SPARC, StrongARM, and IA-32 (x86). The Java virtual machine runs on top of the microkernel. All device drivers are written in Java and executed by the virtual machine. A graphics and windowing system implementing the AWT API is also written in Java.
JavaOS was designed to run on embedded systems and has applications in devices such as set-top boxes, networking infrastructure, and ATMs. It comes with the JavaStation.