JN: OS for an embedded Java network computer

In early 1996, the Computer Science Department at UC Santa Cruz agreed with National Semiconductor to design a custom embedded operating system to support the Java Virtual Machine (JVM). Our goal was to tightly integrate Java with a realtime kernel on a small, single-chip, embedded PC attached to the Internet. By the end of 1996, we had succeeded in implementing the first operating system designed and developed in an academic environment specifically to support Java. This article reviews the lessons we learned from what is most likely the first custom designed operating system-other than JavaSoft's JavaOS-that runs the complete JVM. Our current system, the Java nanokernel (JN), supports a simple Web server written in Java and provides a Java interface to a color Connectix camera.