uint8_t framebuffer[32]  = // 32 columns x 8 lines black or white pixels
{
  0x00, 0xFF, 0x08, 0x08, 0x08, 0xFF, 0x00, 0xFF,
  0x89, 0x89, 0x81, 0x81, 0x00, 0xFF, 0x80, 0x80,
  0x80, 0x80, 0x00, 0xFF, 0x80, 0x80, 0x80, 0x80,
  0x00, 0xFF, 0x81, 0x81, 0x81, 0xFF, 0x00, 0xBF,
};

enum color_t : uint8_t {black, white};

void setPixel(uint8_t c, uint8_t l, color_t color) { // 0 <= c < 32 and 0 <= l < 8
  switch (color) {
    case black: // write a 0 in the corresponding bit
      bitSet(framebuffer[c], l); // https://www.arduino.cc/reference/tr/language/functions/bits-and-bytes/bitset/
      break;
    case white: // write a 1 in the corresponding bit
      bitClear(framebuffer[c], l); // https://www.arduino.cc/reference/tr/language/functions/bits-and-bytes/bitclear/
      break;
  }
}

color_t readPixel(uint8_t c, uint8_t l) { // 0 <= c < 32 and 0 <= l < 8
  return (bitRead(framebuffer[c], l) == 1) ? white : black;
}

void printScreen() {
  Serial.println("------------------------------------");
  for (uint8_t l = 0; l < 8; l++) {
        Serial.print("| ");
    for (uint8_t c = 0; c < 32; c++) {
      Serial.write(readPixel(c, l) == white ? '*' : ' ');
    }
    Serial.println(" |");
  }
  Serial.println("-----------------------------------\n");
}

void setup() {
  Serial.begin(115200);
  printScreen(); // will show our initial Hello pattern

  // remove the '!' at the end
  for (uint8_t l = 0; l < 8; l++) setPixel(31, l, white);
  printScreen();

  // clear up the screen (pixel by pixel)
  for (uint8_t l = 0; l < 8; l++)
    for (uint8_t c = 0; c < 32; c++)
      setPixel(c, l, white);
  printScreen();

  // fill up the screen (pixel by pixel)
  for (uint8_t l = 0; l < 8; l++)
    for (uint8_t c = 0; c < 32; c++)
      setPixel(c, l, black);
  printScreen();
}

void loop() {}