Tiny Operating Systems
A Real-Time Operating System kernel for the Atmel AVR microcontroller, incorporating tasks, memory management, semaphores, queues, and other features. New project at ~SourceForge, but nothing published yet.
Real Time Multitasking Kernel for the Atmel AVR.
AVR Mini Threads
A nanoKernel for the AVR AT90S1200.
BeRTOS is a completely free, open source, real time operating system (RTOS) suitable for embedded platforms. Runs on many microprocessors and microcontrollers, ranging from 8 bits to 32 bits CPUs and even PCs.
ChibiOS/RT is designed for deeply embedded real time applications where execution efficiency and tiny code size are desiderable features. The system is implemented as a library to be linked with the application code, the OS and the application code together form the image to be loaded on the target device.
An Open Source, highly portable, networked, multi-tasking operating system for memory-constrained systems. There are ports for MSP430, Atari ST, AVR, Commodore C64, Casio ~PocketViewer, Game Boy, Game Boy Advance, GP32, VIC 20, Apple II, CBM PET and, and, and.
A portable, Open Source Real Time Kernel.
Usable in all but the tightest micro-controller environments, The focus is on the tiny-to-small, deeply embedded environment.
Phoenix-RTOS is the realtime operating system intended for embedded systems. The main goal of the project is to develop free and portable realtime operating system for common hardware platforms like single board computers and system on chips.
A highly configurable and very fast real time operating system (RTOS). It targets a wide range of architectures, from very small 8 bit processors and microcontrollers up to very huge platforms. Ports are available for ARM, AVR, PPC, 6502 and 8086.
TinyOS An Open Source operating system designed for wireless embedded sensor networks.
XMK The eXtreme Minimal Kernel was designed from the ground up to be very small with respect to ROM, RAM and CPU processing resources. The original targeted platforms were 8bit microcontrollers with only 4K to 8K of ROM and 512 bytes of RAM.
Tiny TCP/IP Stacks
A small independent implementation of the TCP/IP protocol suite. Originally created by Adam Dunkels, it is now actively developed by a team of developers headed by Leon Woestenberg.
NAT for lwIP
BSD-licensed minimal NAT implementation for lwIP.
An Open Source TCP/IP stack, which provides TCP/IP connectivity to tiny embedded 8-bit microcontrollers.
IP libraries and code for tiny systems
the bozotic HTTP server
bozohttpd is a small and secure http version 1.1 server. its main feature is the lack of features, reducing the code size and improving verifiability.
Easy to use web server for Windows and UNIX. Mongoose provides simple and clean API for embedding it into existing programs. Targeting Web application developers, embedded system developers, and people who need to setup file sharing quickly.
Systems based on Nut/OS
BTnut is the operating system used for the BTNodes autonomous wireless communication and computing platform. BTnut is based on Nut/OS and provides a basic Bluetooth Stack (HCI, L2CAP, RFCOMM) together with support for multi-hop networking over Bluetooth Scatter Networks. The Bluetooth Stack can be used by other projects freely (BSD-License).