eCos (Embedded Configurable OS) is an open source, configurable, portable, and royalty-free embedded Real Time Operating System. It is written in C++, provides all the usual OS things. You configure the OS so that the parts you don't need aren't loaded to the embedded system. eCos is released under a modified GPL that allows for its use in embedded systems without having to GPL the embedded application.
Ficl (Forth inspired command language) is an ANS Forth interpreter written in C. Unlike traditional Forths, this interpreter is designed to be embedded into other systems as a command/macro/development prototype language. Ficl provides object extensions that can be used to wrap methods and structures of the host system without altering them.
fistgen is the FiST language code generator, used to create stackable file systems out of templates and a high-level language. This package comes with stackable file system templates for Linux, Solaris, and FreeBSD. It also contains several sample file systems built using the FiST language: an encryption file system, a compression file system, and more - all of which are written as portable stackable file systems.
JBoss is an Open Source, standards-compliant, Enterprise JavaBeans application server implemented in pure Java. JBoss provides JBossServer, the basic EJB container and JMX infrastructure, JBossMQ for JMS messaging, JBossMail for mail, JBossTX for JTA/JTS transactions, JBossSX for JAAS based security, JBossCX for JCA connectivity, and JBossCMP for CMP persistence. It integrates with Tomcat Servlet/JSP container and Jetty Web server/servlet container, and enables you to mix and match these components through JMX by replacing any component you wish with a JMX-compliant implementation for the same APIs. The goal is to provide a full J2EE stack in the Free/Open Source software world.
KernelDriver automates your Windows 2000/NT, Windows Me/98/95 and Linux device driver development by providing you with powerful tools for hardware debugging, driver code generation, and driver debugging. KernelDriver supports PCI / USB / ISA and EISA drivers. KernelDriver for Windows and Linux includes the powerful Driver Wizard. Using the Driver Wizard you can graphically debug your hardware by "peeking" and "poking" at it without writing a single line of code. After your hardware is diagnosed, use the Driver Wizard to generate a complete kernel mode device driver which will drive your hardware.
leJOS is a Java-based replacement firmware (OS) for LEGO Mindstorms programmable bricks, including RCX and NXT. It supports threads, exceptions, synchronization, floating point arithmetic, strings, and so on, but there is no garbage collection yet. It is also designed to be portable to other small devices.
NetBSD is a free, secure, and highly portable Unix-like operating system available for many platforms, from large-scale server systems to powerful desktop systems to handheld and embedded devices. Its clean design and advanced features make it excellent in both production and research environments, and the source code is freely available under a business-friendly license. NetBSD is developed and supported by a large and vivid international community. Many applications are easily available through pkgsrc, the NetBSD Packages Collection.
SOLO (ShagOs LOader) is an x86 bootloader that can directly load and execute protected-mode 32-bit ELF, a.out, and plan9-a.out binaries. It contains a simple boot shell and can run customized scripts to provide boot menus, password protection, etc., at boot time. It comes with commands for scanning for available video modes, unzipping gzip'ed files, and a kernel interface that allows it to call back into 16-bit real mode for BIOS calls, etc. Some debugging facilities are also provided, such as default trap handlers and the ability to set a hardware breakpoint. The initial console I/O can be redirected over a serial port for headless systems.