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CT-800 dedicated chess computer running open source software.

The author of the CT800 computer and chess engine is Mr. Rasmus Althoff, a German programmer and chess enthusiast. His project was published in 2016 and is constantly being developed.

This project is licensed under the GNU General Public License version 3.

The CT800 chess computer has a built-in LCD display and a keyboard for entering moves. The computer has many modes e.g. play, analysis, mate solver and time controls. The computer can also save/load games and play them back later.

You can't buy it, but you can build it yourself thanks to extensive documentation.

Documentation of the CT800 computer and engine is available on the developer's website.

You can find the following information there:

  • The CT800 chess computer manual in PDF format, which describes its functions, how to use it, software updates and troubleshooting.

  • A wiring diagram and parts list of the CT800 chess computer, which you need to build your own copy.

  • Binary files and source code for the CT800 chess engine.

The project is superbly documented.

In addition to schematics, source codes, etc., it also contains an excellent user manual, which, like all other documents of this project, is user-oriented.

Document: manual-ct800.pdf

Document: auxboard.pdf

The CT800 chess engine in its latest version 1.44 is based on an alpha-beta algorithm with many improvements. On dedicated computer it plays around 2100-2200 Elo with the strength of a chess expert.

On my MacBook, it presents grandmaster strength: 2607 Elo, meaning it is a worthy opponent and playing / training partner even for discerning chess players.

Source: MCERL (ongoing)

CT800 chess engine has versions for popular operating systems such as Windows, Linux, Mac, Raspberry-Pi, Android.

Because of its support for the UCI protocol, the CT800 chess engine allows you to enjoy its unique style of play on popular applications and chess GUIs.

So let's take a look at how the CT800 chess engine handles challenging opponents.


First opponent: Deep Junior playing with black.

Junior is a real tough "guy"; one of the toughest computer players. Brave, precise, not shying away from complications.

Although nowadays, it can't compare with the strongest, because it hasn't been developed for many years. In its time, it was Junior who was one of the few who got the chance to play a match with Garry Kasparov – one of the best human chess players of all time.

Who does not remember Junior's beautiful sacrifice (Bxh2+!!) in one of the games with G.Kasparov. Junior is a great chess engine and multiple Computer World Champion.

White was in command of the CT800 having just Junior against him, an opponent of such a great class of opponent.

The following position, is one of the typical ones in which Junior crushed his opponents: two black Bishops having a lot of space, a Queen and... an unstoppable desire to attack the white King.

The 33rd white move, what did CT800 do ?

It did not move to the defense. Oh no!

It played a beautiful 33.c5! sacrificing a pawn and bringing its Queen into play.

Junior accepts the challenge. Of course, the pawn doesn't interest it.


There are several exchanges and a reduction of material on the chessboard. And although CT800's material advantage increases, the position is balanced; both players have to play extremely precisely.

CT800 pushed pawn forward, 37.d7

This is the kind of game Junior loves, and CT800 doesn't avoid it either!


Junior finally strikes directly at the white King's position. CT800 has two Rooks instead of two Bishops.

Ct800 chess engine responds calmly and with precision.


The battle dust settles slowly, Junior defends the draw.

A nice game in which CT800 did not give way to his titled opponent.

Download ZIP • 4KB


In the game below, the CT800 shows that it can play aggressively by calculating far ahead.

White played Scorpio, a well-known strong chess engine with a long tradition.

Scorpio had earlier advanced the white pawn to the h4 field with the hope of future h5 and attacking the black King's position.

The CT800 did not wait for what was coming and attacked first.


Scorpio accepted Knight's sacrifice and several exchanges followed.

At the cost of a figure, the CT800 has significantly weakened the position of the white King, which is now defended only by the white Bishop with the support of the white Queen.

Few moves later, CT800 decides to remove the white Queen from the chessboard with a nice maneuver.


Although the position materially seems equal, CT800 having at its disposal heavy figures with the Queen in the lead and strong black pawns in the center, tilts the outcome of the game in its favor.


After a few more moves, the black pawns become unstoppable.


CT800's forward-looking play leads to its victory.

Download ZIP • 3KB

I am very impressed with the entire CT800 project.

The amount of work put in, the high quality of the documentation, the capabilities of the device itself and the chess engine. Bravo !

CT800 is an open-source project that is worthy of interest by any lover of computer chess, electronics and chess engines programming.

I am sure that if the CT800 were to go into mass production, it would find many buyers, whom it would certainly satisfy.

Many thanks to Mr. Rasmus Althoff for his work and for making the CT800 project available to all interested and the chess community.

Android – Compiled by Archimedes

Download 7Z • 4.19MB

Linux arm64 & x64 – Compiled by Darius

Download 7Z • 3.98MB
Download 7Z • 3.98MB

Mac Apple Silicon & Intel – Compiled by Darius

Download 7Z • 3.98MB
Download 7Z • 3.98MB

Windows x32 & x64 – Compiled by Darius

Download 7Z • 4.01MB
Download 7Z • 4.01MB


In the Files area you will find free chess engines for download.


* Diagrams generated using Scid 5.0.


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