🐟 Koi-DOS

A DOS-like operating system for modern PCs. Boots from a USB stick on a real UEFI machine. No Windows or Linux underneath.

⬇️ Download · What it can do · Commands · FAQ

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🚀 Try it in 3 steps

1. Download koi-dos-0.9.img.zip from Releases and unzip it.
2. Write it to a USB stick with Rufus (choose DD image mode) or balenaEtcher.
3. Boot from the stick (usually F12, F11, F8 or Esc at power on).

You get a Z:\> prompt. Look around, then type SETUP if you want to install it on a disk.

Warning

SETUP erases the whole disk you pick. It never offers the stick you booted from and asks you to type the disk name to confirm, but if the computer has anything important on it, try Koi-DOS in a virtual machine first.

🖥️ Run it in a virtual machine instead

VirtualBox: new machine, type Other, version Other/Unknown (64-bit). In System, tick Enable EFI. Attach koi-dos-0.9.vdi to the SATA controller.

QEMU (Linux):

qemu-system-x86_64 -m 2G -machine q35 -drive format=raw,file=koi-dos-0.9.img \
  -drive if=pflash,format=raw,readonly=on,file=/usr/share/edk2/ovmf/OVMF_CODE.fd

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✨ What it can do

💻 Feels like DOS	Z:\> prompt, dir, copy, cd, batch files, AUTOEXEC.BAT, pipes and > redirection
📁 Real files	Reads and writes FAT32 on hard drives, SSDs (SATA and NVMe) and USB sticks. Long file names work
⌨️ Keyboard and mouse	PS/2 and USB, touchpads with two-finger scrolling. English, Russian, Ukrainian and Greek layouts (Alt+Shift)
🌐 Internet	Wired Intel network cards and phone USB tethering. ping, downloads over HTTP and HTTPS
📦 Package manager	dosget install fetches signed programs and drivers from the internet
🔊 Sound	Built-in sound on most laptops and desktops (Intel HD Audio). Plays WAV files
🖼️ Pictures	Views PNG, JPEG, GIF and BMP
🗂️ File manager	Koi-Commander: two panels, mouse, file viewer and notepad
🎮 Games	A pack of seven games, DOOM (bring your own DOOM.WAD), Quake shareware
🧵 Modern inside	64-bit kernel written from scratch, programs in their own protected memory, threads, TLS 1.3

🚫 What it cannot do (yet)

• ❌ Wi-Fi. Use a network cable or USB tethering from your phone.
• ❌ Old DOS programs. It looks like DOS but runs its own 64-bit programs, not MS-DOS .EXE or .COM files.
• ❌ Old BIOS-only PCs. It needs a UEFI machine (almost everything from 2012 onward).
• ❌ Secure Boot. Turn it off in the firmware settings.
• ❌ NTFS, exFAT, ext4. Only FAT32 disks are readable.
• ❌ Windows. One program owns the screen at a time.
• ❌ Printers, Bluetooth, webcams.
• ⚠️ 3D graphics only on Intel HD 2000/3000 (Sandy Bridge) and in QEMU.

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📖 Commands

Type help at the prompt for the short list. Anything that is not a command is started as a program.

📁 Files and folders

Command	What it does
dir [path] [/w]	List files. /w shows names only
cd <folder>	Go into a folder. cd .. goes up
Y:	Switch to drive Y:
type <file>	Show a text file
more <file>	Show a file one screen at a time
copy <from> <to>	Copy a file. copy *.txt backup works too
xcopy <folder> <folder>	Copy a folder with everything inside
del <file>	Delete a file (erase also works)
ren <old> <new>	Rename (rename also works)
md <name>	Make a folder (mkdir)
rd <name>	Remove an empty folder (rmdir)
tree [path]	Draw the folder tree
attrib [+-RHSA] <file>	Show or change read-only, hidden, system, archive
find "text" [file]	Lines containing the text. /v /c /n /i
sort [file]	Sort lines. /r reverses
edit <file>	Text editor
show <picture>	Picture viewer
play <file.wav>	Play a sound file

💽 Disks

Command	What it does
vol, label	The volume name
disk	All disks and partitions
chkdsk [d:] [/F]	Check a disk. /F repairs
format <partition>	⚠️ New empty filesystem. Erases everything on it
part <disk>	⚠️ New partition table. Erases the whole disk
setup	⚠️ Install Koi-DOS on a disk
sysvol [d:]	Which drive the system lives on

🌐 Network and packages

Command	What it does
net	Network status
net start	Get an address automatically (DHCP)
net set <address> ...	Set an address by hand
ping <host>	Check that a host answers
get <host>[/path] [file]	Download a page or file
dosget list	Programs available to install
dosget install <name>	Install a program
dosget update	Update everything installed
dosget drivers	Install drivers this computer needs
dosget remove <name>	Uninstall
drivers	Which drivers are loaded

⚙️ System

Command	What it does
ver	Version and build
mem	Memory, devices and drives
pci	Everything on the PCI bus
date [y-m-d], time [hh:mm]	Show or set the clock
layout [en|ru|uk|el]	Keyboard layout
screen [WxH|max|default]	Screen resolution
color	Change the prompt colours
sound, sound volume <0-100>	Sound device and volume
beep [hz] [ms]	Play a tone
set [name=value]	Environment variables (PATH, PROMPT)
start <program>	Run a program without waiting for it
reg	Registry editor for the prompt
log [file]	The system log. log KOI.LOG saves it to a file
selftest, crypto	Self checks
keys, pointer	Test the keyboard and the mouse
cls	Clear the screen
shutdown, reboot	Power off or restart
credits	Who made this

📜 Batch files

Put commands in a .BAT file and run it by name. AUTOEXEC.BAT in the root of the system drive runs at startup.

echo, rem, pause, goto label, if exist, if errorlevel, if a==b, if not, for %%f in (...) do, call, shift, %1...%9, %NAME%. Ctrl+C stops a program or a batch file.

@echo off
if "%1"=="" goto usage
copy %1 Y:\backup
echo Saved %1
goto end
:usage
echo Usage: backup file
:end

↪️ Redirection and pipes

dir > list.txt         save output to a file
echo more >> list.txt  add to a file
sort < list.txt        read input from a file
dir | find "BAT"       pass output to another command

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📦 Packages

Installed with dosget install <name>:

Package
commander	Koi-Commander, two-panel file manager
games	Seven games in one program
dosfetch	System info screen
lua	The Lua programming language
doom	DOOM (needs your own DOOM.WAD)
quake	Quake shareware episode (needs 3D graphics)

Drivers (i915 for Intel HD 2000/3000, virtgpu for QEMU) are installed by dosget drivers.

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❓ FAQ

Why is the system drive Z: and not C:?

A: and B: were for floppies, C: was simply the first free letter. Koi-DOS starts from the other end: the system is Z:, other drives get Y:, X: and so on.

My computer does not boot from the stick.

Turn on UEFI boot in the firmware settings and turn off Secure Boot. Legacy/CSM mode is not supported.

No internet.

Only wired Intel network cards and USB tethering from a phone work. Plug in, then type net start. net shows what was found.

Something does not work on my hardware.

Type log KOI.LOG, copy that file to a USB stick and open an issue with it attached.

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🛠️ For developers

Building from source

On Fedora:

sudo dnf install gcc binutils mingw64-gcc qemu-system-x86-core edk2-ovmf dosfstools mtools
make          # loader, kernel, programs, drivers, sdk/
./qemu.sh     # build test disks and boot in QEMU

Debian/Ubuntu: gcc binutils gcc-mingw-w64-x86-64 qemu-system-x86 ovmf dosfstools mtools. Windows: use WSL2.

qemu.sh settings: KEEP_IMAGE=1 reuses disks, KOI_SPLIT=1 uses the installed layout, KOI_AUDIO_WAV=out.wav records sound. Extra arguments go to QEMU.

Writing programs

sdk/ has everything needed: koi.h, koicc and the linker script. See sdk/README.md.

#include "koi.h"

int main(const char* arguments) {
    koi_print("Hello from Koi-DOS!\n");
    return 0;
}

sdk/koicc hello.c    # makes HELLO.EXE

Source layout

Folder
boot/	UEFI loader
kernel/	kernel, drivers, shell, network
drivers/	loadable drivers (.SYS)
programs/	built-in programs and libraries
sdk/	kit for writing programs
include/	shared headers

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💖 Credits

Made by Koi Ayame. Font: Terminus by Dimitar Toshkov Zhekov.

Built through intense pain and heartbreak. I miss you so much... Rest in peace, @nonconformie.

📄 License

MIT, see LICENSE. Programs installed as packages may have their own licences. The font is under the SIL Open Font License 1.1.