Espruino Home Computer

Many of us learnt to program on Sinclair Spectrums, Commodore 64s, BBC Micros or similar. Computers that booted straight up to a prompt and that encouraged you to play with them.

In this tutorial you'll learn how to make your own JavaScript computer with VGA output in a few hours using Espruino!

Also see the Pixl.js Home Computer as the display.

You'll Need

Wiring Up

Keypads and Breadboard

Back of the base plate

Pico with wires

Installed Pico

Installed Pico

Installed Pico

Note: There's no need to connect Blue and Red if you just want a green display!

Installed Pico


Make sure your Espruino Pico has up to date firmware!

Put the following in the right-hand side of the Web IDE, click Send to Espruino, and when that is done type save() in the left-hand side.

To fully use the computer you'll need to power it from a non-computer-based power source like a USB phone charger or battery.

// Keyboard wiring
var KEYROW = [B10,B13,B14,B15, B6,B5,B4,B3];
var KEYCOL = [A4,A3,A2,A1, B9,B8,A8,B7];

// Key Maps for Keyboard
  "\x01\\zxcvbnm,./ \x80\x83\x81",
  "\x01|ZXCVBNM<>? \x80\x83\x81",

/* If a char in the keymap is >=128,
subtract 128 and look in this array for
multi-character key codes*/
var KEYEXTRA = [
  String.fromCharCode(27,91,68), // 0x80 left
  String.fromCharCode(27,91,67), // 0x81 right
  String.fromCharCode(27,91,65), // 0x82 up
  String.fromCharCode(27,91,66), // 0x83 down
  String.fromCharCode(27,91,53,126), // 0x84 page up
  String.fromCharCode(27,91,54,126), // 0x85 page down
// Shift status
var hasShift = false;
function setShift(s) {
  hasShift = s;
  digitalWrite(LED1, s);

// Convert an actual key into a sequence of characters
// And send to Loopback (where the console is)
function handleKeyPress(e) {
  var kx = e>>3;
  var ky = e&7;
  if (ky>3) { // turn into long row
  var key = hasShift ? KEYMAPUPPER[ky][kx] : KEYMAPLOWER[ky][kx];
  if (key=="\x01") {
  } else {
    if (key && key.length) {
      if (key.charCodeAt(0)>127)
        key = KEYEXTRA[key.charCodeAt(0)-128];
      //USB.write(JSON.stringify(key)+"\r\n"); // debug

var term; // the terminal
var g; // graphics

function onInit() {
  // set up the keypad
  require("KeyPad").connect(KEYROW, KEYCOL, handleKeyPress);
  // Start TV out
  g = require('tv').setup({ type : "vga",
    video : A7,
    hsync : A6,
    vsync : A5,
    width : 320,
    height : 240,
    repeat : 2, // amount of times to repeat each line
  // use a larger font instead of the default

  // Set up the terminal
  term = require("VT100").connect(g, {
    charWidth : 8,
    charHeight : 12,
    marginTop : 10, // might want to tweak these depending on your monitor
    marginLeft : 20,
    marginBottom : 16

  // take characters from Espruino, and push them into the VT100 terminal
    for (var i in e) term.char(e[i]);
  // copy characters coming down USB into the 'loopback' device
  USB.on('data',function(e){ LoopbackB.write(e); });
  // Now move the console to Loopback


Now it's working:

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