Open-source alternatives to Os01

CS-Xmind-Note is a collection of structured mind maps and conceptual diagrams serving as a comprehensive knowledge base for computer science fundamentals. It functions as an academic reference and study guide, organizing core subjects into a visual mapping of interdependent technical concepts. The project utilizes an XMind-compatible schema to model complex domains through hierarchical nodes and relational concept mapping. This approach allows for the visual representation of technical layers, linking hardware specifications to software abstractions. The knowledge base covers several primary

This project is an ARMv8 assembly programming guide and tutorial designed to teach the translation of high-level logic into low-level machine instructions. It serves as a low-level systems programming reference for writing and executing code specifically for the ARMv8 architecture. The resource provides instructions for cross-platform assembly implementation, focusing on unifying symbol naming and memory addressing to ensure source code builds across different operating systems. It also covers the integration of assembly routines with higher-level languages using standardized calling conventi

This project serves as an educational resource for learning and implementing low-level assembly language optimizations. It provides a structured guide for developers to master hardware-specific instructions and manual performance tuning, focusing on the translation of high-level code into efficient machine-level operations for resource-constrained environments. The materials emphasize techniques for maximizing computational throughput in multimedia processing. By covering instruction-level parallelism, register management, and data parallelism, the project enables the development of software

This project is a tutorial and framework for building a low-level, bare-metal operating system from scratch using the Rust language. It focuses on ARMv8 kernel development specifically for the Raspberry Pi 3, providing the resources necessary to implement a monolithic kernel that runs directly on hardware without an underlying operating system. The project distinguishes itself by providing a complete embedded cross-compilation suite within a containerized environment to ensure consistent builds. It includes a dedicated kernel deployer that uses a serial interface and chainloader to load and b

This project is a comprehensive educational framework designed to guide learners through the complexities of systems engineering and low-level software development. It provides structured learning paths that integrate hardware simulation, source code analysis, and project-based exercises to help developers master the foundational concepts of computer architecture, operating systems, and firmware design. The curriculum distinguishes itself by emphasizing direct interaction with system internals, requiring learners to examine and modify existing open-source kernel and driver implementations. By

This project is a freestanding kernel written in Rust that boots on x86 hardware without a standard library. It serves as a low-level system implementation focusing on the creation of a bare metal operating system. The system implements a bootable disk image toolchain that transforms source code into binaries compatible with a bootloader. It features a custom memory allocator for dynamic memory management and an x86 kernel implementation that includes paging, interrupt handling, and VGA text mode. The project covers several core capability areas, including low-level memory management through

TinyGo is a specialized compiler and development toolkit designed to bring the Go programming language to resource-constrained microcontrollers and WebAssembly environments. It provides a bare-metal runtime environment that enables high-level code execution without the need for a traditional operating system, utilizing an LLVM-based backend to generate efficient machine instructions. The project distinguishes itself through aggressive optimization techniques tailored for small hardware, including a static memory allocation strategy and whole-program dead code elimination that significantly re

HelloSilicon is a programming guide and tutorial for writing and debugging low-level 64-bit assembly code specifically for Apple Silicon processors. It serves as an architecture reference for interacting with macOS and iOS kernel services using system calls and hardware registers. The project provides specialized instruction on foreign function interfacing to bridge assembly with high-level languages like C or Python. It also includes a toolkit for configuring Mach-O binaries and compiling universal binaries and dynamic libraries for cross-hardware compatibility. The material covers low-leve

This project is an educational resource for developing bare-metal operating systems and kernels from scratch on Raspberry Pi hardware. It provides a structured guide to systems programming using the Rust language, focusing on the implementation of core kernel components that execute directly on ARM-based hardware without the support of an underlying operating system or standard library. The tutorials emphasize a modular architecture that separates hardware-independent kernel logic from processor-specific and board-specific configurations. By utilizing a hardware abstraction layer and distinct

The Linux kernel is a monolithic operating system core that manages hardware resources, memory, and process scheduling across diverse computing architectures. It provides a standardized, POSIX-compliant environment for application execution while maintaining a modular driver framework that allows for the dynamic loading and removal of hardware interfaces. The project is distinguished by its high-performance concurrency toolkit, which utilizes lockless synchronization primitives and read-copy-update mechanisms to manage shared data access in multi-core environments. It incorporates a comprehen

This project is a comprehensive technical interview preparation guide and computer science knowledge base. It serves as a structured study resource designed to help software engineers review core engineering concepts and prepare for professional coding assessments. The repository focuses on a wide array of theoretical and practical domains, including detailed references for mobile application architecture and operating system fundamentals. It provides curated materials on software architecture patterns and network protocol analysis to support professional development. The content covers foun

The RISC-V ISA Reference Manual is the official technical specification defining the RISC-V instruction set architecture. It serves as a hardware architecture standard and a comprehensive set of rules and definitions that govern the interaction between software and RISC-V hardware. The project is maintained as markdown-based technical documentation, which is converted into a searchable, web-based reference. This specification provides the necessary reference for processor hardware design, low-level firmware development, embedded systems programming, and compiler backend engineering. It inclu

30dayMakeOS is an educational hobby operating system project designed for the x86 architecture. It implements a monolithic kernel and a custom bootloader that transitions the CPU from real mode to 32-bit protected mode to enable flat memory addressing. The project focuses on low-level system development, featuring a custom graphics driver for direct pixel-buffer rendering and window management without an existing operating system. It includes an x86 bootloader that loads the kernel from disk into memory. The system covers core kernel capabilities including round-robin task scheduling for pro

This project is a collection of minimal operating systems, bootloaders, and hardware drivers used to demonstrate low-level x86 system programming and hardware interfacing. It serves as a kernel development toolkit and a system programming lab designed for testing architecture concepts and hardware behavior within a system emulator. The repository provides reference implementations for creating bootable disk images and loading kernel stages. It includes guides for implementing protected mode transitions, memory paging, interrupt descriptor tables, and symmetric multiprocessing on x86 hardware.

Redox is a POSIX-compliant, microkernel-based operating system written entirely in Rust. By utilizing a memory-safe language for the kernel and all system components, the project eliminates common vulnerabilities such as buffer overflows and use-after-free errors. Its architecture relies on a minimal kernel that manages only essential hardware and process isolation, delegating all other system services to unprivileged user-space processes. The system distinguishes itself through a modular design where hardware drivers and system services run as independent user-space daemons, allowing them to

This project is a tutorial for developing a custom bare metal operating system specifically for the Raspberry Pi 4. It provides the guidance and resources necessary to write software that interacts directly with hardware without the use of a pre-existing kernel. The project centers on an ARM64 cross-compilation toolchain and a build pipeline that transforms source code into raw binary images. It utilizes linker scripts to define physical memory addresses and section placements, ensuring the resulting binary loads at the correct hardware entry point. The codebase covers direct hardware interf

This is an open-source, crowd-sourced wiki textbook that teaches Linux system programming in C. It covers the core operating system concepts of process management through the fork-exec-wait model, dynamic memory allocation using implicit free list heap allocators, inode-based file systems, inter-process communication via pipes and shared memory, POSIX threads with synchronization primitives, signal-based asynchronous notification, virtual memory with page table translation, and runtime diagnostics using Valgrind and GDB. The textbook distinguishes itself by providing practical, implementation

This repository provides the original source code and binaries for legacy disk operating systems. It serves as a historical software archive and a reference implementation for early personal computer operating systems. The project is designed for software archaeology, legacy operating system research, and the study of foundational kernel design. It allows for the technical analysis of historical software architecture and implementation. The codebase covers several core system areas, including monolithic kernel design, segmented memory addressing, and file allocation table indexing. It also i

Tock is a secure embedded operating system and microcontroller kernel designed to isolate untrusted applications and drivers. It functions as a memory-safe process isolator that uses a combination of hardware memory protection and language-level type safety to execute mutually distrustful applications on bare metal. The system distinguishes itself through a hardware abstraction layer that decouples high-level components from specific microcontroller implementations using standardized traits. It further employs a virtualization layer to allow multiple independent software components to share a

Asterinas is a memory-safe operating system kernel designed to prevent data races and memory corruption. It functions as a Linux-ABI compatible kernel, enabling the execution of existing Linux binaries and container workloads while providing a declarative operating system distribution model. The project distinguishes itself by acting as a virtual machine container host and a confidential computing guest OS, allowing it to run within hardware-isolated Trusted Execution Environments such as Intel TDX. It implements a minimal trusted computing base by isolating unsafe low-level operations and se

Unleashed Firmware is a custom firmware modification for portable multi-tool devices designed to expand the capabilities of radio frequency, infrared, and contactless authentication hardware. It functions as a comprehensive platform for wireless security auditing, signal analysis, and hardware interaction, enabling users to capture, decode, and emulate signals across various communication protocols. The firmware distinguishes itself through a modular plugin architecture that allows for the dynamic addition of signal analysis and attack capabilities without requiring a full system recompile. I

embedded-notes is a collection of technical study guides and development notes focused on embedded Linux, Linux kernel internals, and C programming. It serves as a reference for embedded systems development and a preparation resource for technical interviews in the field. The project provides detailed documentation on writing device drivers, managing virtual memory, and understanding kernel internals. It also includes guides on IoT network protocols, such as MQTT and TCP/IP, and outlines the architectural details of chip architectures and hardware peripherals. The material covers a broad sur

CppGuide is a curated collection of educational resources and practical guides focused on C++ server development, Linux kernel internals, concurrent programming, network protocols, and security exploitation. It provides structured learning paths for backend developers, covering everything from interview preparation to building high-performance network servers and understanding operating system fundamentals. The guide distinguishes itself by offering in-depth, hands-on tutorials that walk through real-world implementations, including building a Redis-like server from scratch, designing custom

InterviewGuide is a comprehensive technical interview preparation platform that covers the full spectrum of software engineering recruitment, from foundational computer science concepts through to offer negotiation. It provides structured learning paths across algorithms, operating systems, databases, networking, and programming languages, with a particular emphasis on C++ and Go. The platform aggregates real interview experiences and company-specific questions from major tech employers, offering candidates a searchable database of past written exam problems and detailed accounts of actual int

This project is a comprehensive technical guide and course for reverse engineering iOS applications. It serves as a manual for dissecting mobile binaries using disassembly and debugging tools to analyze internal application logic and behavior. The material functions as a reference for ARM assembly and Objective-C theories, providing the necessary framework to translate low-level machine code into human-readable logic. It combines theoretical study with practical exercises to validate the use of reverse engineering tools on real-world binaries. The scope covers static binary analysis, dynamic

This project is a collaborative knowledge base and technical learning resource that provides a detailed breakdown of the internal processes occurring within modern computing environments. It serves as a comprehensive educational reference, tracing the step-by-step operations triggered by common user interactions and network requests to explain how hardware and software components interact across the entire stack. The guide distinguishes itself by offering deep technical insights into the journey from physical input to visual output. It covers the low-level mechanics of hardware interrupt hand

freeCodeCamp is an open-source, web-based educational platform designed to facilitate software engineering skill acquisition through a structured, project-driven curriculum. It combines theoretical instruction with hands-on coding exercises, requiring users to build functional applications to demonstrate mastery of programming concepts. The platform provides a browser-integrated workspace that evaluates learner proficiency through automated testing of code submissions against predefined functional requirements. The platform distinguishes itself by integrating technical training with professio