E93-2026

The new E93! E93-2026!

Overview

A minimal 32-bit operating system kernel that boots via GRUB2 (Multiboot specification). Written in C and x86 Assembly.

Features

• VGA Text Mode - 80x25 text console with 16 colors
• VGA Graphics Modes - Multiple graphics modes supported:
  • Mode 12h: 640x480, 16 colors
  • Mode 13h: 320x200, 256 colors
  • Mode X: 320x240, 256 colors (planar)
  • Mode Y: 320x200, 256 colors (planar)
• Userspace Programs - ELF32 executables loaded from ISO9660 filesystem
• Interactive Shell - Built-in shell with commands:
  • beep - Play a beep sound
  • cd <dir> - Change directory
  • cls - Clear the screen
  • curdir - Print working directory
  • dir [path] - List directory contents
  • echo <text> - Print text
  • exit - Exit shell and halt system
  • help - Show available commands
  • idedevs - Show IDE devices
  • mem - Show memory information
  • pcidevs - Show PCI devices
  • run <program> - Run a program
  • version - Show version information
• System Calls - INT 0x80 based syscall interface
• Memory Info - System memory information via Multiboot
• File I/O - Read files from the ISO9660 filesystem
• PC Speaker - Beep sound support
• IDE Controller - IDE/ATAPI device detection and information
• PCI Bus - PCI device enumeration with pci.ids database lookup
• ISO9660 - Read-only filesystem support

Prerequisites

• nasm
• qemu (x86 system, pa audio required for beeps)
• GRUB2
• xorriso
• mtools
• GCC (with 32-bit support)
• i686-elf-gcc cross compiler (optional, recommended)

Building

Using System GCC (Easier)

make -f Makefile.gcc iso

Using Cross-Compiler (Recommended)

make iso

Running

Boot from ISO (via QEMU)

make run    # or: make -f Makefile.gcc run

User Programs

User programs are located in src/user/programs/. Each .c file is compiled into a separate ELF32 executable and included in the ISO.

Included Programs

Program	Description
hello	Simple hello world demo
shell	Interactive command shell
vga_demo_12h	VGA 640x480 16-color graphics demo
vga_demo_13h	VGA 320x200 256-color graphics demo
vga_demo_mode_x	VGA Mode X 320x240 graphics demo
vga_demo_mode_y	VGA Mode Y 320x200 planar graphics demo

Creating New Programs

See the SDK documentation for creating user programs.

Quick start:

1. Copy sdk/template/program.c to src/user/programs/myprogram.c
2. Edit as needed
3. Run make -f Makefile.gcc iso
4. In shell: run myprogram

For graphics programs, use sdk/template/graphics_demo.c as a starting point.

Project Structure

E93-2026/
├── src/
│   ├── boot/           # Boot code (boot.asm)
│   ├── kernel/         # Kernel code (kernel.c, idt.c, syscall.c, etc.)
│   ├── drivers/        # Device drivers (vga.c, keyboard.c, ide.c, etc.)
│   ├── lib/            # Kernel libraries
│   ├── include/        # Kernel headers
│   └── user/           # Userspace
│       ├── include/    # User program SDK headers
│       ├── programs/   # User program source files
│       └── user.ld     # User program linker script
├── sdk/                # SDK documentation and templates
├── build/              # Build output (generated)
├── Makefile            # Cross-compiler build
└── Makefile.gcc        # System GCC build

Copyright and License

Copyright (c) 2026 Erdem Ersoy (eersoy93). Licensed under the Apache License 2.0. See the LICENSE file for license text.

E93-2026 written with the help of GitHub Copilot!

NOTE: media/pci.ids is licensed under GNU GPLv2. See LICENSE.GPLv2 for the license text.