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Winners and runners-up to Dick Smith’s Noughts & Crosses Competition We were pleased to receive nine entries in this competition, with four different winners selected for the $500 prizes (plus signed copies of Dick Smith’s autobiography). Most of the runners-up did a great job too. Here are all the details. We’ll start with the four winners, then mention the other five entries. Most submissions span multiple pages, and we don’t have space to reproduce all of that information here, but we’ll try to include the basic details of each submission. Winner #1 – Dr Hugo Holden (most ingenious entry) We received this submission first, and frequent readers will recognise Dr Holden as a regular contributor to the magazine. We had to award him the prize for two reasons. Firstly, his design is relatively simple yet based entirely on discrete logic and an EPROM chip spread across two neat PCBs. Secondly, he used a very clever method to allow the computer to play the game. He 82 Silicon Chip fabricated discs with Xs and Os on them, and the game is played by placing those discs in the grid of 3 x 3 depressions on the device’s front. The discs contain magnets with opposite polarities for Xs and Os, and Hall effect sensors determine which discs are placed where. When the computer wants to make a move, it lights up the LEDs in one of the recesses, and the human player places the computer’s disc there. They then make their own move, and the process repeats until someone wins or it’s a draw. If the computer wins, it makes a beep to alert the player. We think that’s a very innovative and intuitive ‘user interface’. Not only does it look and feel like a board game, but it’s also very easy to play, and it looks very professional too. It’s so good that we plan to run it as a project article later this year. Winner #2 – Max Morris (youngest entrant) Max is 12 years old, and his entry uses an array of pushbutton switches and a separate array of LEDs as the user interface, controlled by an Arduino Australia's electronics magazine Uno. He supplied the code as a ‘sketch’ that uses much the same approach as a human player, assessing the situation and deciding whether it needs to block the opponent’s move or try to form a line. He sent photos of the finished version, reproduced here, plus his original breadboard prototype. We think it’s a great effort given his age, and he definitely deserves the prize for the youngest entrant to submit a design that meets all the criteria. You can see a video of Max’s machine in operation at siliconchip. com.au/Video/6335 Winner #3 – Mark Wrigley (best entry without a micro) While we felt that Dr Holden’s entry was very clever, and it does not use a microprocessor, Mark’s design is also very commendable. As for the photo, well, let’s just say it’s a good thing that neatness wasn’t one of the criteria! Mark used bicolour LEDs and an array of pushbuttons for the user interface, and similarly to Dr Holden, he used a flash chip to store the data needed for the machine to make its siliconchip.com.au moves. And again, like Dr Holden’s machine, that chip drives some discrete logic that maintains the game state, decides when to make a move and so on. Mark was also fairly economical with his use of ICs as, besides the flash chip, it mainly comprises some latches and decoders. So overall, a simple concept and an elegance to the circuitry hidden behind that “rat’s nest” assured him a place on the podium. His use of a chopping board, similar to the way people used to build radios on breadboards, was also quite endearing. Winner #4 – Martin Irvine (simplest entry) Steve Schultz’s incredible 3D-printed electromechanical Noughts & Crosses machine has to be the most ambitious submission we were given. It earned him a special extra prize. Martin was the last person to enter the competition – at the last minute, in fact – but he took a different approach from most other entrants that we felt earned him the final prize. He used the fewest discrete parts to build his machine, with a total of just 30 components, including the nine LEDs and nine buttons that are almost unavoidable. It would be hard to use any fewer! Essentially, what he did was take a 16-pin microcontroller and connect one pushbutton and one bicolour LED to each of nine digital input/output pins. The LEDs are furnished with current-limiting resistors. The micro can turn on one LED to be either green or red by driving the associated I/O pin high or low, or it can switch that pin to be a digital input to sense when the corresponding button is pressed. The only other parts on the board are a coin cell for power and a bypass capacitor. He also designed and assembled quite a neat PCB for his submission, shown below. You can see Martin’s entry in action in the YouTube video at https://youtu. be/LjqZjLTh7x0 We like the simplicity of Martin’s design so much that we plan to run it as a small project in an upcoming issue. Special prize winner: Steve Schultz ► Dick decided to award a ‘special’ unannounced $250 prize to Steve as he was the only person so enthusiastic about this challenge that he tried to build an electromechanical noughtsand-crosses machine, similar to the one Dick made all those years ago. In many ways, what Steve attempted to do was considerably more difficult than what Dick did because he fabricated many of the parts for the machine himself. He did this by 3D-printing most of the mechanical parts. It uses solenoids to drive plastic selectors, a bit like the old uniselectors that Dick used. It appears that Steve built a fully working electromechanical Noughts & Crosses playing machine, so he might have been a winner. But he admitted that he hadn’t had time to thoroughly test it, to verify that it would always play the correct strategy. Still, he did such a good job that Dick decided to award him a prize anyway. You can see a demonstration video of Steve’s machine at siliconchip.com. au/Video/6334 ► siliconchip.com.au Martin Irvine went to the trouble of populating this neat little credit-card style PCB. It has just 30 onboard parts in total and runs from a coin cell. Talk about a “rat’s nest!” But what Mark Wrigley’s design lacked in aesthetics, it made up for in the cleverness of the circuit. Australia's electronics magazine April 2022  83 ► If there was a prize for the least amount of assembly, Keith Anderson would have won it with this minimalistic build. David Such’s design is the definition of overkill, ► using a 32-bit micro plus an FPGA to play the game. But there’s no doubt that it is an effective solution! Runner-up #1: Keith Anderson Runner-up #3: Dr George Galanis Final entrant: Angus McPherson Keith’s entry was the other submission we were considering for winning the prize for the simplest entry. If you only count the parts you have to buy and put together, there are just two: an Arduino Uno and an Adafruit TFT colour touchscreen. That’s the fewest parts of any entry. Of course, both those parts have a lot of discrete components on them, and there are no doubt many, many transistors spread across both devices. So ultimately, we couldn’t conclude that this was the simplest design. Still, it’s a solid effort, and we will publish the details (including the Sketch code which, let’s face it, is basically everything) in an upcoming Circuit Notebook entry. Dr George Galanis submitted a treatise covering the logic required to play Noughts & Crosses in great detail. He also sent CAD files of the 12 (!) boards he designed that carry said logic. Apparently, it forms a monster of a game-playing machine when put together. The circuitry is spread across eight schematic sheets! He obviously put a tremendous amount of work into the design, so while we didn’t feel his entry fell into any of the winning categories, we awarded him a smaller runner-up prize. You have to admire the dedication involved in creating such a design, even though it would be impractical to build it (see below). Angus also attempted to design a Noughts & Crosses playing machine using mainly discrete logic, with quite a few transistors added into the mix. Unfortunately, he ran out of time to finish it, so he was not considered for one of the prizes. Still, we appreciate that he sent in his partially completed work. Conclusion We were very pleased with the number and diversity of the entries. Each entrant took a different approach to solving the problem, and in most cases, they succeeded. We hope that they enjoyed making the designs as much SC as we did seeing them. Runner-up #2: David Such If there were a prize for the most unnecessarily overpowered entry, David Such would surely have won with his entry that includes an FPGA (field-programmable gate array) IC! He built it on an Arduino MKR Vidor 4000 board which includes both a SAMD21 32-bit microcontroller and the aforementioned FPGA, and he used both to play the game. The user interface is quite clever, consisting of an 8x8 bicolour rectangular LED matrix to display the current state of play and a pushbutton/ joystick shield for control. We were sufficiently impressed with David’s design that we plan to feature it in the Circuit Notebook section of an upcoming issue. 84 Silicon Chip An Altium-produced 3D rendering of Dr George Galanis’ monster entry. He was nothing if not thorough. You have to appreciate the dedication involved in putting this much work into the competition. Australia's electronics magazine siliconchip.com.au