The Odyssey² was one of the many also-rans in the first wave of cartridge-programmable game consoles.  Notable primarily for being the first (and possibly the only) game console to come with a built-in alphanumeric keyboard, it was an odd duck in a number of ways – its graphics and sound capabilities were limited (though better than the 2600 at the time), the "one life and you're out" gameplay of most of the games was kind of quirky, and only a handful of games made any real use of the integral keyboard.  Even with Leonard "Mr. Spock" Nimoy promising us that the Odyssey² had "The excitement of a game, with the mind of a computer" on TV, it never enjoyed the kind of success achieved by the "big three" (Atari, Intellivison, and Colecovision).  Still, it did have its share of fun and unique games – especially the "Master Strategy" series, which was particularly unique in attempting to blend the videogame and board game genres to make the gameplay more challenging and complex.

However, one thing it did share with its more popular bretheren is a complete lack of A/V-style outputs; like most consoles and home computers of the day, the Odyssey² provides only an RF output on channel 3 or 4.  In addition, most of the consoles also had permanently-attached joysticks, rather than detachable/replacable ones.  Of course, so does the Intellivision – but since the Odyssey² controllers are just simple 8-way joysticks with a single fire button, there's no reason why they shouldn't be easily replaceable with any standard Atari-style joystick.

Now, before we begin, let us recite together the standard disclaimer mantra:

WARNING!

If you decide to attempt these modification to your own console, you do so strictly at your own risk!  While there's nothing intrinsically dangerous inside an Odyssey² console, and the needed modifications aren't terribly complicated for anyone with a basic grasp of electronics, it is still possible to damage your console (or yourself!) if you don't know what you're doing!  Please do not attempt this modification if you don't at least have some basic component-level electronics experience, and/or are not willing to assume the risk of damaging your Intellivision if you make a mistake along the way.

Getting an Odyssey2 console apart couldn't be simpler – just three hex-cap screws on the bottom, and the two halves come apart cleanly.  The bottom half of the shell doesn't have anything in it, and as you can see in these photos, even the top half doesn't have all that much to it.  If it weren't for the alphanumeric keyboard, the unit could easily be about half the size it is.  All that extra space is good for me, though, since it means I have plenty of room to work with when it comes to installing the video-amp board and running all of the extra signal and game-controller wiring.

Removing the circuit board is equally simple; two more hex-cap screws, located right next to the ROM-cartridge connector, and it lifts right out – and unlike the Intellivision and Colecovision consoles, there are no big metal PCB shields to remove, either!  The only thing to be careful of is the flex-cable connecting the membrane keyboard to the logic board – try not to twist or pull on it as you work.  Actually, you might not even need to remove the PCB at all in order to carry out these modifications, since all of the connections you need to get to are conveniently accessable on the solder side of the PCB as it is.

It's actually quite amazing how little there is to the logic board, really – there are only 13 chips on the entire board, most of which are nothing but simple 7400-series TTL chips.  All of the heavy lifting is being done by an Intel 8048 microcontroller and an Intel 8244 graphics-and-sound chip.  The 1K (that's K as in "kilobytes") BIOS ROM is built into the 8048, and the total amount of available RAM is 320 bytes – no, not "kilo-" or "mega-"bytes, just bytes; 64 of them inside the 8048, and the remaining 256 inside that big 24-pin DIP next to the CPU.