Kernel Mode Linux is a technology which enables the execution of user programs in a kernel mode. In Kernel Mode Linux, user programs can access kernel address space directly. Unlike kernel modules, user programs are executed as ordinary processes (except for their privilege level), so scheduling and paging are performed as usual. Although it seems dangerous, the safety of the kernel can be ensured through such methods as static type checking, software fault isolation, and so forth.
Visopsys is an alternative operating system for PC compatible computers. Under development since late 1997, this system is small, fast, and open source. It features a simple but functional graphical interface, real preemptive multitasking, and virtual memory. Though it attempts to be compatible in a number of ways, Visopsys is not a clone of any other operating system. You can demo the distribution from a "live" CD, USB stick, or floppy disk.
Fiwix is an operating system kernel based on the Unix architecture and fully focused on being Linux compatible. It is designed exclusively for educational purposes, so the kernel code is kept as simple as possible for the benefit of students. It runs on the 32-bit x86 hardware platform, and is compatible with a good base of existing GNU applications.
WANPIPE S-series is a family of intelligent multi-protocol WAN and ADSL adapters that support data transfer rates up to 8Mbps. All WAN protocols supported by WANPIPE are implemented in firmware and run on the card. An advantage of an intelligent adapter is that it offloads the system CPU and improves stability. By adding a Sangoma WAN/ADSL component to the Linux kernel, one can create a powerful multi-T1/ADSL router/firewall with proven reliability of Linux. Sangoma S-series cards support an optional on board T1/E1 CSU/DSU that eliminates all external components of a traditional routing solution: i.e. T1/E1 line can be directly connected to the card. WANPIPE supports the following protocols, ATM, ADSL, Frame Relay, PPP, MULTILINK PPP, CHDLC, X25(API), BitStreaming (API), BiSync(API), and SDLC(API). Furthermore, WANPIPE supports custom API development such as: Credit card verification, Voice-over IP, Satellite Comm. All device drivers are part of the standard Linux Kernel distribution.
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.
QP is a family of lightweight software frameworks for building responsive and modular real-time embedded applications as systems of cooperating, event-driven active objects (actors). The QP family consists of QP/C, QP/C++, and QP-nano frameworks, which are all strictly quality controlled, superbly documented, and commercially licensable. The behavior of active objects is specified in QP by means of hierarchical state machines (UML statecharts). The frameworks support manual coding of UML state machines in C or C++ as well as automatic code generation by means of the free QM modeling tool. All QP frameworks can run on bare-metal MCUs, completely replacing a traditional RTOS. Ports and ready-to-use examples are provided for all major CPUs, such as ARM Cortex-M, ARM7/9, MSP430, C28x, C55x, RX, R8C, AVR32, AVRMega, PIC24/dsPIC, as well as Arduino and mbed. QP/C and QP/C++ can also work with a traditional OS/RTOS, such as: POSIX (Linux, QNX), Windows, VxWorks, ThreadX, and uC/OS.
uLan Driver provides 9-bit character message- oriented communication protocol that is transferred over an RS-485 link. The physical layer consists of one twisted pair of leads, and RS-485 transceivers. Supported hardware includes OX16C954 PCI based add-on cards, USB-to-uLan converters, the i82510 RS-485 card, or simple active converter dongle for standard PC RS-232 ports. The whole set of libraries and support tools is available for building embedded devices. They range from low level firmware boot-loaders and debugging tools up to object oriented properties browsing and manipulation and process data communication channels mapping.
Linux is a clone of the Unix kernel, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance. It has all the features you would expect in a modern fully-fledged Unix kernel, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and TCP/IP networking.
DMAring demonstrates a novel generic network interface card driver architecture which works in hybrid interrupt-polling mode to deliver superior real-time performance on Linux, Red Hat Linux, or Linux-RTAI-LXRT (a real-time co-kernel for Linux with user level extension). Existing Linux drivers saturate the CPU at a much lower packet rate than the maximum possible wire line packet rate, but this driver allows vanilla network cards to be used for high speed packet capturing.
ReactOS is an advanced operating system providing a ground-up implementation of a Microsoft Windows XP/Windows Server 2003-compatible operating system. It aims to achieve complete binary compatibility with both applications and device drivers meant for XP and NT 5.2 operating systems by using a similar architecture and providing a complete and equivalent public interface. Written completely from scratch, ReactOS is not a Linux based system, and shares none of the UNIX architecture.