Reliving the Atari 2600

I am currently taking a course titled “Hackers in the Bazaar”, which is, by all acounts, the greatest class ever. Anyway, we spent class today playing classic video games brought in by students. I brought in a SNES and a copy of Mortal Kombat).

Additionally, I spent about an hour and a half yesterday creating something a bit special for the occasion. My dad keeps his old Atari 2600 up in my closet, along with a chest full of games. We no longer have the hardware to hook the Atari up to a television set, but the controllers still work fine. To help preserve the experience of playing old Atari games, I threw together an adapter that allows me to connect the Atari controllers as a USB gamepad.

I bought two DE-9 connectors a while back for this. The pinout for the Atari controllers is available online, but since the controllers are not “smart” - they are just switches with no ICs or anythig - it is easy to confirm the pinout with a multimeter. The connections necessary for the classic joystick were made, and 10 10k ohm resistors were used to pull down the inputs. A Digispark Pro was used to enumerate the USB joystick.

Here is the code for the Digispark - it is very simple:

#include "DigiJoystick.h"

char BUTS[] = { 6, 5, 2, 1, 0, 7, 8, 9, 10, 11 };
void setup() {
  for (int i = 0; i < 10; i++) {
    pinMode(BUTS[i], INPUT);
  }
}

void loop() {
  DigiJoystick.delay(50);
  int p = 0;
  for (int i = 0; i < 10; i++) {
    p |= digitalRead(BUTS[i])<<i;
  }
  DigiJoystick.setButtons((char)(p&0xFF), (p>>8)&0xFF);
}

The project was definitely successful - I played a few rounds of one of my all time favorites ) with Breezy. We played eight rounds and ended up tying 4-4 before watching our classmates fail at trying to run a lemonade stand. The joysticks themselves hurt my hands just as much as I remember, so that’s nice. In the future, I might have to add the front panel switches of the Atari 2600 to really capture the feel of the old system.