CuriOS Documentation

Overview

CuriOS is a simple educational and hobbyist operating system kernel designed to demonstrate fundamental OS concepts and provide a platform for learning low-level system programming. Starting from a basic bootloader, it enters 32-bit protected mode and sets up a minimal runtime environment, including screen output capabilities.

Components

• Bootloader (boot.asm): Initializes the system and loads the kernel into memory.
• Kernel (kernel.asm, kernel.c): Represents the core part of the operating system, managing system resources, and providing basic services including screen output. It now includes functionality to remap the PIC and handle keyboard interrupts.
• Makefile: Automates the compilation and linking process.
• Linker Script (linker.ld): Defines the memory layout of the kernel.
• Run Script (run_os.sh): Streamlines the process of building and running the OS.
• IDT Functionality (/idt/idt.asm, /idt/idt.c, /idt/idt.h): Implements the Interrupt Descriptor Table (IDT) and handles keyboard interrupts.
• Memory Utilities (/memory): Contains a simple memset function for memory management.
• I/O Utilities (/io/io.asm, /io/io.h): Provides basic I/O functionality for writing to ports.

IDT Functionality (/idt)

Key Features

• IDT Setup: Configures the Interrupt Descriptor Table for handling hardware interrupts.
• Keyboard Interrupt Handler: Handles keyboard press and release, displaying output on the screen.

Detailed Functionality

• Interrupt Handlers: Implements specific interrupt service routines, such as for keyboard interrupts.
• IDT Initialization: Sets up IDT entries for various interrupts and loads the IDT.

Memory Utilities (/memory)

• Contains a simple memset function, essential for low-level memory operations.

I/O Utilities (/io)

• Provides basic functions for interacting with hardware I/O ports, crucial for device communication.

Kernel Modifications

• PIC Remapping: kernel.asm now includes functionality to remap the Programmable Interrupt Controller.
• Keyboard Interaction: Displays a message on the screen when a key is pressed and released.

Build Instructions for CuriOS

Prerequisites

• Ensure make, NASM (Netwide Assembler), GCC, and QEMU are installed on your system.

Steps

The run_os.sh script automates the building and emulation of the kernel. Specifically, it does the following:

1. Clean Previous Builds: Use make clean to clear previous build artifacts.
2. Compile and Build: Execute ./build.sh to compile and link components.
3. Run with QEMU: Run qemu-system-i386 -hda ./os.bin

Notes

• Ensure build.sh and run_os.sh are executable (chmod +x).
• Check all dependencies and environment setup for x86 assembly and C development.

Additional Notes

• CuriOS, designed primarily for educational purposes, now includes extended functionality like IDT handling, simple memory operations, and basic I/O utilities.
• It demonstrates more advanced OS development concepts such as interrupt handling, memory management, and hardware I/O operations.
• This documentation reflects the latest state of CuriOS and will be updated as the project evolves.