ADAM’74, a retro screen for 8-bit computers #VintageComputers #Retrocomputers “Adafruit Industries – Makers, hackers, artists, designers and engineers!

The Adam74 is a small project that tries to act as a small terminal that a hobbyist might like to use for a small 8-bit computer that they are experimenting with.

It relies on 7 pins to represent a 7-bit ASCII character and another pin the connected device strobes to tell the Adam74 that there is a character pending on the input pins to lay into memory buffer and display. The prevalence of small, easily interfaced LCDs and inexpensive microcontrollers to drive them made this project a no-brainer.

Like a terminal, the Adam74 manages text wrapping, scrolling. It also handles many control codes like carriage return and bell. Other control codes are reinterpreted to give a simple cursor control interface, etc.

While researching early terminals, it was no surprise that I came across the ADM-3A terminal. And it won’t surprise you that I took inspiration from this machine for both the overall shape of the acrylic stand I designed for it as well as the name itself.

The “74” in Adam74 is meant to suggest the time: around 1974.

Here are the parts needed to complete the PCB:

  • Teensy 4.0 (PJRC)
  • 320×240 color LCD display based on ILI9341 (PJRC and other places)
  • 74LVC245 Level Shifter (Adafruit and other locations)
  • Buzzer (Adafruit and other locations)
  • 100 ohm, 1/4 Watt resistor (2×)
  • 0.1uF (3×) ceramic capacitor (Adafruit and other places)
  • 1N4148 Small Signal Diode (Adafruit and other places)
  • 0.1″ male header pin strip (Adafruit and other places)
  • 20-pin IDC male connector (2 × 10, 2.54 mm pitch) (optional)

Source code as well as Gerber files (and an SVG file you can use to cut the acrylic backing) are available on the EngineersNeedArt GitHub repository and the project described here.

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