Skip to content


Folders and files

Last commit message
Last commit date

Latest commit



40 Commits

Repository files navigation


TetrOS is a small feature rich Tetris clone which is written in Assembly. It fits completely into a 512 byte boot sector as it requires only 446 bytes (which is the maximum allowed size of the first stage boot loader in the master boot record (MBR) of a drive) and is executed during the boot sequence before any operating system is loaded. Actually, it does not need any existing operating system. TetrOS is an operating system, hence the suffix OS in its name.

Video that shows TetrOS in action:

TetrOS - Teris in 512 byte boot sector

And this is the complete machine code:

TetrOS - Machine code

Running TetrOS

There are two options to run TetrOS. Either in an emulator like qemu or via an installation of TetrOS in the boot sector of a real disk, USB stick or some other media.

Running via qemu

Simply run make run. This will execute qemu with the right parameters to run TetrOS. If you're using Ubuntu and qemu is not intalled on your system you can install it via sudo apt-get install qemu.

Running via an USB stick

First, copy the image to an USB stick. For example, if your USB stick is on /dev/sde use the following command to overwrite the first sector of the USB stick with the TetrOS image:

sudo dd if=tetros.img of=/dev/sde

After that you should be able to boot the stick to play TetrOS.


  • Each brick shape has a unique color.
  • Blinking cursor is not visible.
  • Left and right arrow to move a brick.
  • Up arrow to rotate a brick.
  • Down arrow to drop a brick.
  • Game over detection. It stops if a new brick could not be placed.
  • Selects the next brick at random via a linear congruential generator.
  • Nice playing field.

Features missing due to size limits

  • Scores and highscores.
  • Intro.
  • Game over message and restart without rebooting.
  • Show next brick.
  • Increase speed.

Compiling the sources

The repository already contains an image which you can use for testing. However, if you want to compile the image from the sources you need nasm, a general prupose x86 assembler to be installed on your system. On Ubuntu you can can install it via the command sudo apt-get install nasm. On macOS you will need homebrew to install nasm and binutils.

If nasm is installed you can compile the sources by executing make. This will create the image tetros.img. After that you can run the image via qemu or you can copy the image via dd on an USB disk or a disk (see above).

I have tested it with nasm 2.11.08 on Ubuntu 16.04.

Similar projects


I would like to thank the following persons for contributing to TetrOS.