OKL4 Microkernels are a family of second-generation microkernels based on the original designs and implementations by Jochen Liedtke. Originally implemented in highly tuned i386-specific assembly language code, the API has seen extensive development in a number of directions, both in achieving a higher grade of platform independence and also in improving security, isolation, and robustness. There have been various re-implementations of the original binary kernel interface and its higher level successors, including L4Ka::Pistachio, L4/MIPS, and Fiasco. For this reason, the name L4 now applies to the whole microkernel family including the L4 kernel interface and its different versions.
QP is a family of lightweight and portable frameworks for modeling and coding UML state machines in C or C++. Designed for real-time embedded systems, QP can replace an RTOS or work with one. It has been ported to many MCUs (ARM Cortex-M3/M0, ARM7/9, MSP430, TMS320C28x, AVR, PIC18/PIC24/dsPIC, M16C/R8C, H8, 68HC08, ColdFire, PSoC, NiosII, 8051/80251, PSoC) and OSs (Linux/POSIX, Win32, VxWorks, QNX, ThreadX, uC/OS-II).
amforth is an extendible command interpreter for the Atmel AVR ATmega microcontroller family. It has a turnkey feature for embedded use as well. It does not depend on a host application. The command language is an almost compatible ANS94 forth with extensions. It needs less than 8KB code memory for the base system. It is written in assembly language and forth itself.