Recreating the 1973 TV Typewriter with Arduino

Arduino Nano

Arduino IDE

Fermion AdKey

Box 525 1% precision resistors - 17 values

<html><body><p>In 1973, Radio-Electronics magazine published the TV Typewriter, a project by Don Lancaster that transformed an ordinary television into a text terminal. Without using a microprocessor or conventional RAM, it could scan a simple keyboard and generate a composite video signal, displaying the typed characters on the TV screen. </p><p> </p><figure><img src="https://projects.arduinocontent.cc/6a00f28b-5256-4a28-b997-d3346f6b53b3.jpg"/><figcaption>Radio Electronics</figcaption></figure><p> </p><p> </p><p>Beyond its practical use, the TV Typewriter <strong>became an influential milestone in the history of personal computing</strong>. It demonstrated that a television could serve as a computer display, paving the way for many early microcomputers. </p><p> </p><figure><img src="https://projects.arduinocontent.cc/42c07c87-de45-4520-b154-c8da4f8210f0.jpg"/><figcaption>TV Type</figcaption></figure><p> </p><p>For quite some time I wanted to pay tribute to Don Lancaster's design, but I couldn't find an elegant and inexpensive way to recreate the keyboard. While searching through a drawer of spare parts, I rediscovered a DFRobot Fermion AdKey module. Each AdKey provides ten push buttons through a single analog output by using different voltage levels. By combining three modules I could cover the entire alphabet, plus a few special keys such as period, space, and delete. </p><figure><img src="https://projects.arduinocontent.cc/b54b50aa-70d3-4762-a68f-bdc97705ff41.png"/><figcaption>AdKey module</figcaption></figure><p>Generating the video turned out to be relatively straightforward thanks to the TVOut library. The real challenges appeared elsewhere: the AdKey library could not reliably read three modules simultaneously, the enclosure required thirty perfectly aligned holes, and TVOut's interrupt-driven design imposed a few software limitations. Eventually everything came together, resulting in TV Type. </p><h3>Parts</h3><p> </p><ol><li>1 × <a href="https://www.dfrobot.com/product-67.html?tracking=hOuIhw4fDaJRTdy4abz04npbQC78dqxBkqVt7XMFYxEXj2s0ukWgm71wbut0ewUP">Arduino Nano </a></li><li>3 × <a href="https://www.dfrobot.com/product-2267.html?tracking=hOuIhw4fDaJRTdy4abz04npbQC78dqxBkqVt7XMFYxEXj2s0ukWgm71wbut0ewUP">DFRobot Fermion AdKey modules </a></li><li>1 × 330 Ω resistor </li><li>1 × 1 kΩ resistor </li><li>1 × RCA male connector </li><li>9 × Female-to-female Dupont jumper wires </li><li>1 × DC barrel jack </li><li>1 × 3D printed enclosure </li><li>4 × M3 screws </li><li>10 × 2.5 mm screws </li></ol><p> </p><h3>Video Circuit</h3><p> </p><figure><img src="https://projects.arduinocontent.cc/453987a3-5383-4b43-b95b-fe8c30e455de.png"/><figcaption>Video out circuit</figcaption></figure><p> </p><ol><li>Connect Arduino **D7** to a **330 Ω** resistor. </li><li>Connect Arduino **D9** to a **1 kΩ** resistor. </li><li>Join both resistor outputs and connect them to the **center pin** of the RCA connector. </li><li>Connect Arduino **GND** to the **outer shield** of the RCA connector. </li><li>Connect an LED between **D8** (anode) and **GND** (cathode). </li></ol><p> </p><p>For the keyboard: </p><p> </p><ol><li>Daisy-chain **VIN** and **GND** across the three AdKey modules. </li><li>Connect their analog outputs to **A3**, **A4**, and **A5**. </li></ol><p>Also connect the DC jack to Arduino VIN and GND </p><h3>The Keyboard (Almost QWERTY)</h3><p>The keyboard is built from three DFRobot Fermion AdKey modules. Each module reads ten buttons through a single analog input, making it possible to build a thirty-key keyboard while consuming only three analog pins.  The example DFRobot library worked well with a single module, but it was not designed to read three modules simultaneously. I ended up writing my own analog mapping routine to achieve reliable readings. </p><p>Because of the physical layout of the AdKey boards, a true QWERTY arrangement is impossible. The first row ends with the letter **O**, while the second begins with **P**. To compensate, I engraved every key label directly onto the enclosure. </p><p> </p><figure><img src="https://projects.arduinocontent.cc/a4377702-9a24-4ec3-b4cc-c98635af9bcd.png"/><figcaption>Enclosure</figcaption></figure><h3>Enclosure</h3><p>Designing the enclosure was probably the most difficult part of the project. Thirty button openings and their corresponding labels had to fit into a very small area while remaining comfortable to use. </p><p>The enclosure is printed in two PLA parts without supports. Rotate each part 180° before slicing so the engraved letters face upward. Pausing the print before the lettering allows a filament color change for improved readability. </p><p>You can find the files at https://cults3d.com/en/3d-model/gadget/tv-type </p><h3>Software</h3><figure><img src="https://projects.arduinocontent.cc/bcf2eeb5-0375-4643-a26e-ee8f01367e43.png"/><figcaption>Arduino IDE code</figcaption></figure><p>Open the Arduino IDE and install TVOut Library. </p><p>Connect the Arduino Nano via USB, open the sketch, select Arduino Nano and ATmega328P (Old Bootloader), then upload. </p><p><em>One important note: TVOut relies heavily on interrupts. Using `Serial.println()` for debugging will interfere with the video signal and usually corrupt the display. </em></p><h3>Startup Logo</h3><p> </p><figure><img src="https://projects.arduinocontent.cc/81aff9bd-40c3-4dd8-9109-6ee466e44d3d.png"/><figcaption>Logo conversion</figcaption></figure><p> </p><p>The startup logo is a 128 × 64 monochrome bitmap. After designing it, I converted using Marlin. </p><p>and assigned to the array with </p><code class="code">PROGMEM const unsigned char Logo[] = {};</code><p>The bitmap is displayed with: </p><code class="code">tv.bitmap(1, 20, Logo);</code><h3>Final Thoughts</h3><p> </p><figure><img src="https://projects.arduinocontent.cc/e8ee5b24-47c6-4e07-ba79-cbab766833c7.png"/><figcaption>Start screen</figcaption></figure><p> </p><p>Except in apocalyptic scenarios, technology rarely moves backward. Yet revisiting the history of computing is fascinating because it reveals the ideas that shaped today's machines. Projects like the TV Typewriter remind us how ingenious early designs were, and how fortunate we are to have Arduino that let us recreate these historical machines with just a handful of inexpensive components. </p><h3>Video</h3><p><a href="https://www.youtube.com/shorts/Q_JVIlyIvLk">https://www.youtube.com/shorts/Q_JVIlyIvLk </a></p><h3>More about TV Typewriter</h3><p>https://open.spotify.com/episode/47dvC8gKBU0geFenW8OAwq</p><h3>Contact</h3><p>Roni Bandini</p><p><a href="https://www.linkedin.com/in/ronibandini/">https://www.linkedin.com/in/ronibandini/</a></p><p><a href="https://www.instagram.com/ronibandini/">https://www.instagram.com/ronibandini/</a></p><p> </p></body></html>

Recreating the 1973 TV Typewriter with Arduino

Recreate the pioneering 1973 TV Typewriter with an Arduino Nano, 3 numeric keypads, and composite video output to experience one of the projects that inspired the personal computer revolution.