[MOC] Tic-Tac-Toe playing machine (no electronics)

[Joostv]

3 years ago I set myself a challenge to build a mechanical computer that can play Tic-Tac-Toe. I hope you like the result 😊.

Final design: Open studless exterior in 18th-century style and medieval game theme, with Technic interior visible.

 

Gameplay & limitations

The machine starts in the center with 'X', which is represented by crossed swords. The player can play the bottom-right two fields. To play the other fields, the player can rotate the machine, so this isn't really a limitation. After that, all player moves are supported. The machine will reject moves on fields that are already taken (invalid moves). The machine can reach 25 different game states and 19 different game endings. 
The machine responds immediately to a player move, resulting in the player move (shield) and the countermove (swords) becoming visible almost simultaneously. 
After each turn, a single full turn of the dial on the side moves the memory to the correct next position.

 

How it works

I built a cross-section model to explain the mechanism. It is demonstrated in the video below. 

Summary of the video:

The machine uses two types of logic gates: AND gates and OR gates. 

Signal direction is upward. Gravity is used to return the gates to their default positions, which significantly reduces the complexity of the logic gate designs. 

The logic gate network for a single response consists of:

• A first AND gate that reads one bit from memory and has the player key as the second input.
  • The result is fed to an 8-input OR gate that is almost as wide as the machine
  • And the result is fed to a 2-input OR gate that triggers the shield corresponding to the key
• An 8-input OR gate (almost as wide as the machine)
  • The result is connected to one AND gate per field for triggering swords.
  • And the result is fed to an AND gate handling memory addressing.
• A second AND gate for triggering swords, which takes input from the wide 8-input OR gate and a bit from memory.
  • The result is fed to a 2-input OR gate that triggers the swords for the field.
• A shared AND gate for memory addressing, which takes input from the wide 8-input OR gate and a bit from memory.
  • This drops an arm on the memory plate to block it at the correct position. 
  • In an end-of-game situation the arm is not dropped. The memory will move to end-of-game position as a result.
• The two OR-gates to trigger shield or swords, as mentioned earlier.

The machine combines two slightly different versions of the above network so it can have two different responses at any time.

• The OR gates that trigger shields and swords are not duplicated, but triggered by both networks.
• The memory addressing for the two networks is different:
  • One can skip multiple program steps.
  • One always stops at the next step. 
  • As both networks are equally capable, each game state uses the network with the correct addressing behavior.

All the logic gates are optimized to be as small as possible and to function next to each other without a seperating wall.
The entire logic gate network is powered by a key press with a height difference of just one stud. For that reason, everything is mounted on rollers to reduce friction, and horizontal signal distance is limited as much as possible.

The memory plate. 

Not in the video:
Powering the memory movement

 

The memory is pushed forward by a scissor mechanism. The memory does not travel the same distance for every player move, and I really wanted to have only one turn of the dial after every move. Therefore, the memory had to be powered independently from the player's action.

I tried a lot of different solutions: 

1. The first idea was to let the memory fall down (move vertically). That didn't work because the memory was too heavy, and skipping multiple program steps caused excessive stress and force.
2. The second prototype used a memory drum. This did not work well for reading the memory and suffered from bending stress on the central axle.
3. The third idea used gears to transfer power from a weight to the horizontal plate. It had too much friction, sometimes causing the mechanism to refuse to move. It also made resetting heavy to operate.
4. The last (and only succesful) idea was this scissor mechanism, still transferring power from a weight (the part with 'Lude Bene' on it) to the memory plate, but with very little friction. 

Powering the shields and swords

The force of the user's key press is mostly dissipated after passing through the logic gate network and is only suitable for light triggering.

Each shield and set of swords is powered by its own small weight. The weight is held in place by a mechanism that requires only a light trigger to release it. This works very well. I haven't got around to demonstrating this mechanism in images/video yet. 

Reset mechanism

The video below shows the reset system (rewind the video to see another game demo first):

Summary of the video:

• The display is reset using hidden knobs in the decorations on the sides. 
  • Turning these pushes the shields and swords backs and locks the weights that power them behind their triggers
• The memory is reset in three steps:
  • The dial is turned half a turn. This lifts the memory readers, allowing the memory to move
  • The handle is pulled, pushing the memory plate back. 
  • The dial turn is completed to read the memory and allow a new game to start.
• The central field remains unchanged. This is the first move of the machine (crossed swords in the center)

 

Exterior

The design is intended to look like an 18th century machine with a medieval game theme.
The style is studless and I have avoided tile grooves where possible. I used panels (mounted backwards) instead tiles. The back of a 4 wide panel does show a small injection-mold mark, but this is less distracting than a tile groove. I also used a lot of half-plate offsets throughout the buildto hide tile grooves. This was mostly achieved by combining brackets with modified bricks (with studs on the side).

 

Build experience, more images and future of the project

If you have watched any of the video's to the end, it probably didn't escape you that I submitted this project to LEGO Ideas 😉. Like many others, I still dream of seeing my design on store shelves one day.

Besides a rather prominent yellow button, you'll find additional rendered images and a description of the build experience there. In the creator update (which, for some reason, requires login), I included a technical description supported by animated gifs extracted from the first video in this topic. 

https://beta.ideas.lego.com/product-ideas/96a609c5-bffe-4df9-86a5-dbd005514159

 

Thanks for reading all the way to the end,

Joost / MejoliDesign

Edited Sunday at 10:22 AM by Joostv
Typo (memroy instead of memory)

[JunkstyleGio]

That is very, and I mean very very very, nice!

 

Good luck on getting the votes on Lego Ideas! 

[blondasek]

Oh my butt. This would be a brilliant ideas set, showcasing, specially for teenagers, how you can build "computer" without any electronic parts. Amazing!

EDIT: do you experience any lock-ups? 

Edited Sunday at 11:55 AM by blondasek

[N1K0L4]

This is incredible! Great job!

What inspired you to build it?

Since you designed the exterior in 18th century style as you say (it looks amazing btw), did something like that exist back than?

[pleegwat]

Brilliant and beautiful. Supported.

[allanp]

This is very impressive and it looks great too. Front paged.

[Frequenzberater]

Nice to see you found some time to share this beauty here on EB :) 

As I already wrote on Reddit: Stunning work. I love when complex mechanisms meets beautiful aesthetics. 

[Joostv]

@JunkstyleGio, @blondasek, @N1K0L4, @pleegwat & @allanp Thanks 😊
I'll also answer your questions here:

Q: question about lock-ups
A: None on the interior, but the tiles that hide the technic holes on the liftarm on the sides (see image) have caught the housing of the dial once. It gave me quite a scare because I thought I had to dissassemble the whole thing. Luckily all I needed to do was press on the tiles and the problem was solved. I haven't looked into preventing this from happening again yet.



Q: Question about inspiration
A: Every once in a while I have some idea followed by the thought: "Would this be possible with LEGO?". Then I check if somebody did something like that before, and if the answer is 'no', then I get the urge to try and build it. I did magnetically dancing shoes once for pretty much the same reason. In this case there are some very cool builds around that do things with mechanical logic gates or mechanical computing, and some awesome electronic tic-tac-toe playing machines, but not something quite like what I had in mind.

Q: Question about 18th century style and if something existed like this. 
A: The 18th century had lots of automata, these combined mechanisms with a styled exterior and often some animal that was animated by the mechanism. One of the most famous automata was 'the turk', which was a chess playing robot. It was a hoax: A human was hidden inside, but it has all kinds of doors to show the fake internal mechanism. 

Thanks again 😊

  

[Sebeus I]

What a beautiful machine, I love the elegant manner of resetting.

[vascolp]

This is really incredible, brilliant!

 

[ludov]

Amazing! Nice videos too! I like how you -literally- framed the explanation of the mechanisms. 

[1980SomethingSpaceGuy]

Absolutely brilliant. The bug on the memory card hit my geek's home.

Supported and good luck!

[Murdoch17]

Reminds me a bit of WOPPR from WarGames... which started life in the movie as a computer playing tic-tac-toe. Just don't give your LEGO creation the nuclear arsenal codes! (It also reminds me of Charles Babbage's difference and analytical engines)

Great work on this non-electric gaming computer MOC, and remember - the only way to win is not to play!

Edited Sunday at 06:32 PM by Murdoch17

[blondasek]

4 hours ago, Joostv said:

@JunkstyleGio, @blondasek, @N1K0L4, @pleegwat & @allanp Thanks 😊
I'll also answer your questions here:

Q: question about lock-ups
A: None on the interior, but the tiles that hide the technic holes on the liftarm on the sides (see image) have caught the housing of the dial once. It gave me quite a scare because I thought I had to dissassemble the whole thing. Luckily all I needed to do was press on the tiles and the problem was solved. I haven't looked into preventing this from happening again yet.



Q: Question about inspiration
A: Every once in a while I have some idea followed by the thought: "Would this be possible with LEGO?". Then I check if somebody did something like that before, and if the answer is 'no', then I get the urge to try and build it. I did magnetically dancing shoes once for pretty much the same reason. In this case there are some very cool builds around that do things with mechanical logic gates or mechanical computing, and some awesome electronic tic-tac-toe playing machines, but not something quite like what I had in mind.

Q: Question about 18th century style and if something existed like this. 
A: The 18th century had lots of automata, these combined mechanisms with a styled exterior and often some animal that was animated by the mechanism. One of the most famous automata was 'the turk', which was a chess playing robot. It was a hoax: A human was hidden inside, but it has all kinds of doors to show the fake internal mechanism. 

Thanks again 😊

  

interesting. So the whole mechanism is reliable and robust? Even more impressed!

[Joostv]

1 hour ago, ludov said:

Amazing! Nice videos too! I like how you -literally- framed the explanation of the mechanisms. 

Thanks 😊. To be honest about that frame, that solution was born out of necessity: I don't generally use white bricks, and most of my remaining bricks were all different kinds of white (some near yellow 🫣). So I went to a local store and bought a photo frame to cover that up. That looked a lot better. 😉

3 hours ago, Sebeus I said:

What a beautiful machine, I love the elegant manner of resetting.

Thanks! Finding a way to integrate the reset knobs for the display was the main headache. The original plan was to mount them out of sight, but that didn't work out. I was glad I found a way to hide them as decorations.

4 hours ago, Frequenzberater said:

Nice to see you found some time to share this beauty here on EB :) 

As I already wrote on Reddit: Stunning work. I love when complex mechanisms meets beautiful aesthetics. 

Thanks, and thanks for suggesting it 😊.

6 minutes ago, blondasek said:

interesting. So the whole mechanism is reliable and robust? Even more impressed!

Pretty much, yes. 

You can get errors if the machine isn't level (the old secretary with food out desk that is my little building corner definitely isn't level). And strong vibrations (like slamming the table it stands on) can trigger a display (shield/swords) to appear, but that's it. 

49 minutes ago, Murdoch17 said:

Reminds me a bit of WOPPR from WarGames... which started life in the movie as a computer playing tic-tac-toe. Just don't give your LEGO creation the nuclear arsenal codes! (It also reminds me of Babbage's difference and analytical engines)

Great work on this non-electric computer MOC, and remember - the only way to win is not to play!

Thanks! And the last quote is actually true for WOPPR and this machine (the best possible outcome for the player is a draw) 😉

@1980SomethingSpaceGuy, @vascolp just wanted to say thank to you as well 😊

[2GodBDGlory]

That is the most impressive Technic build I've seen in a long time! Very, very nice work! Great documentation, too

[Glaysche]

This is very cool.  This reminds me of the old school mechanical calculators:

 

https://en.wikipedia.org/wiki/Mechanical_calculator
 

Needless to say, if this were released as a Lego Ideas set, it would be day-one purchase for me.

[Toastie]

Hi Joost,

much has been said - this is beyond >everything< I have seen before. "Seen" in terms of your explanations(!), the video itself, the realization, the mechanical logic gates (I am a TTL believer) - it just blew me off. Replayed the video over and over again, just to hear your calm voice, explaining the logic, the mechanics, the reason a mechanical machine can be that fast in responding.

But there is more - the beauty of the build. This is a synthesis of logic, building skills, and the gift to make it look like ... a miracle, a beautiful thing to have, a marvel, a secret ... and more.

Ideas is one place to go. There are others. Should it not get approved, it is, because TLG can't handle it. Not because of not making it to the top. This creation is simply floating above the top.

Thank you very much for your presentation of your wonderful creation. The populated picture frame alone is a demonstration of true LEGO craftsmanship.

All the best
Thorsten      

[mdemerchant]

This is absolutely amazing.  Incredible mechanisms and it looks fantastic as well.  Definitely one of the most impressive builds I have ever seen.

[Jeroen Ottens]

Incredible creation, so original, so full of clever solutions and packaged and explained beautifully. Supported!

[Elysiumfountain]

Simply stunning! I can't remember what number I was, but I definitely supported it, best of luck! 

[Siroco]

Amazing! I would buy it day one. Supported!

 

[Joostv]

@2GodBDGlory, @mdemerchant, @Jeroen Ottens, @Siroco, Thanks for your kind words! 😊
 

21 hours ago, Glaysche said:

This is very cool.  This reminds me of the old school mechanical calculators:

 

https://en.wikipedia.org/wiki/Mechanical_calculator
 

Needless to say, if this were released as a Lego Ideas set, it would be day-one purchase for me.

Love those. I have seen a video of one with electric motor going crazy on a divsion by zero once.
And thanks 😉

@Elysiumfountain, Thanks and congrats on passing 5K 😊, that house is a beauty!

@Toastie Thank you very much! I can't quite describe it, but I'm genuinely touched. Thank you, this made my day 😊

[Morgoth924]

Wow. Incredible! What a machine! Brilliant to see how it operates, beautiful to see how it looks. Supported it straight away. Very well made video's as well. Again: wow.

[Kai NRG]

The mechanics of this are amazing, and it looks phenomenal too!  Very cool project.