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The Naked Minimal Video Recreation: The Odyssey 100

The Naked Minimal Video Recreation: The Odyssey 100

2023-12-10 16:17:00

The primary online game? Debatable. The primary online game console, although, is well-established: the 1972 Magnavox Odyssey, brainchild of Ralph Baer. Nonetheless, the Magnavox Odyssey was costly to make, so Magnavox turned to Texas Devices to create a stripped down model of the Odyssey. A stripped down model of the primary and most primitive console? Oh sure, now we’re actually deep in it. PLUS: Composite mod on a black and white console! 3D printing! Video sign probing with an oscilloscope!

Odysseus, save us

The Magnavox Odyssey is the primary online game console. Magnavox patented it, courts agree, so we all know it must be true. However there’s a few of what the TV Tropes crowd would name ‘Early Installment Weirdness’– the idea of a “online game” wasn’t fairly the identical in 1972 as it’s at the moment. Right here’s an image from the Odyssey manual, displaying a sport of Soccer. Clearly this was an necessary sport, so many pages within the guide are devoted to it; and have a look at the way you play it:

Two cartoons playing a game of Odyssey Football. They surround a table covered in a board game, with the TV to the side

The tv is virtually an afterthought, although it’s used for performs. A lot of the sport occurs as a board sport, with at least six decks of playing cards. Graphics are offered by a chunk of plastic that connected to your CRT tv display screen with static electrical energy. This doesn’t look very similar to somebody enjoying a online game at the moment. Most Odyssey video games have been like this to some extent or one other.

The exception was within the first sport card– oh, sure, the Odyssey did have “sport playing cards”, although they weren’t cartridges within the fashionable sense (Soccer makes use of two totally different playing cards for various kinds of performs), solely connecting and disconnecting totally different elements of the inner logic. Additionally they served as the facility change; you actually pull out the cartridge to show it off. In any case, that distinctive sport was Desk Tennis, Recreation Card #1.

Manual photos explaining a ball bouncing off the paddle

Odyssey Desk Tennis was famously the inspiration (confirmed in courtroom) for Nolan Bushnell’s Pong, although extra on that later. Two spots of sunshine transfer about on display screen, with a middle line dividing the courtroom in two. They’ll push a ball of sunshine forwards and backwards between them, strategizing to hit the ball such that the opposite participant will miss.

The Magnavox Odyssey is usually referred to as a failure, but it surely’s arduous to say that Magnavox considered it that approach; 350,000 models was greater than another online game console earlier than it bought. They invented the idea of promoting extra sport playing cards, and even received Nintendo to fabricate a light-weight gun. However the Seventies have been a time of excessive inflation, and the Odyssey wasn’t low-cost to make. Plus Ralph Baer, ever-curious, needed to make the most of the newfangled built-in circuit know-how.

The Magnavox Odyssey 100. Missing a potentiometer knob.

Behold: the 1975 Magnavox Odyssey 100. It’s in a little bit of a tough form, isn’t it?

The place we’re going, we don’t want options

The Magnavox Odyssey 100 rear, showing off a single screw

The again of the Magnavox Odyssey 100 is held on by a single screw. For those who open it up, you’ll see a cardboard overlay, displaying numerous adjustment knobs, however warning you to not go any additional. Discover the “Rating Vert. Pos.” knob; this identical cardboard overlay was used for the Odyssey 100’s sister console, the Odyssey 200. This isn’t an Odyssey 200, although, so don’t anticipate a bodily rating. You noticed these sliders on the entrance! That not adequate for you?

The Magnavox Odyssey 100 rear, showing off its warning-covered cardboard cover

There’s additionally a place for a whopping six batteries. Discover that conveniently, the motherboard surrounds the battery compartment on all 4 sides, in order that if this was left in a closet in 1975 with batteries left in, and people batteries had leaked within the intervening forty-eight years (which they nearly actually did), some a part of the board will certainly be destroyed. If you wish to purchase one among these, or one other of the numbered Odysseys that used the identical model of case and took batteries, ensure to get an inside photograph before you purchase.

The Magnavox Odyssey 100 PCB

Beneath the cardboard you’ll see the principle PCB. It’s held in by six bolts, which is de facto annoying, and is single-sided. It’s fairly cardboardy.

Cardboardy PCB, with components

Wow, newfangled ICs! In fact, there are 4 of them, nestled between the elements; the thought of doing a complete desk tennis sport with a single IC must await the distant way forward for 1976.

Cardboardy PCB, with holes drilled and unused, but also unlabeled

One factor I discover fascinating is that there are holes drilled for added ICs; these can be used on the Odyssey 100’s associate in crime, the aforementioned Odyssey 200, which added extra options, together with even a primitive type of on-screen scoring. (What, you thought Nintendo invented the technique of sharing elements between two fashions?) The factor that stunned me is just not that they share a PCB– that’s fairly widespread– however as an alternative that the silkscreened textual content is version-specific; the ICs that don’t present up on the Odyssey 100 aren’t labeled right here.

Three holes, one covered

One other proof of shared {hardware} with the Odyssey 200 is that this third gap within the plastic. On the Odyssey 200, each switches change sport choices, whereas the facility change is on the underside. That isn’t the case on the Odyssey 100. Although they’re totally different colours, it appears the identical molds have been used. One other building oddity you may simply handle to make out is the truth that the mud covers on the switches are literally between the plastic of the case and the outer sticker, fairly than elements of the switches and even beneath the case. I ended up having to take away the one on the facility change.

“Composite” “Mod”

A strange barrel-shaped connector

The actual motive I opened up this Odyssey, although, is that this connector on the top of the hard-wired cable. I’ve by no means fairly seen a connector like this earlier than; apparently it was solely utilized by Magnavox on their early consoles. (The unique Odyssey had it removable at each ends, which may be very luxurious) My Odyssey 100 didn’t include the RF field, although, so I’ve no strategy to take care of this.

However that’s positive! I can do a composite mod. What’s that, you say? This console isn’t in shade, so it’s not really composite video? Effectively, who’re you to inform Magnavox they’re unsuitable?

A trace labeled 'COMP. VIDEO'

In fact, it’s a composite of video and sync… or maybe a composite of all the assorted movable components. In any case, it’s referred to as composite video, and says I can simply wire up an RCA cable to it, no amplifier or something. I suppose these older techniques are simply product of sterner stuff. I eliminated the previous cable and threaded my new, a lot shorter cable by means of the opening.

Two potentiometer knobs. One is 3d printed, with a dead giveaway FDM pattern on the top

Having given the Odyssey 100 a bob minimize, I full the look by 3D printing a brand new potentiometer knob. Oh, you didn’t know I had a 3D printer? Thank my spouse for that one; that is really my first use of it; a Creality Ender 3 Neo Max. The mannequin isn’t an ideal match (undoubtedly not shiny sufficient) but it surely seems to be adequate in the dead of night; right here’s the SCAD and STL files if you wish to mock my first makes an attempt. It’s not an ideal match, but it surely seems to be positive from a distance.

The Odyssey 100, with all its potentiometer knobs and a shorter cable

Nonetheless not speaking concerning the video games

So with the Odyssey 100 wanting fairly and all buttoned again up, it’s time to get it on-screen. I had to make use of a 3.5mm to 2.5mm mono adapter with my Atari 2600 energy provide; whereas I complained about the usage of a plug I affiliate with audio within the 2600 article, I admit that that is extra comprehensible right here: the two.5mm plug has an inside change that disconnects the batteries when an influence provide is used. After getting every part powered, although, I bumped into an fascinating problem: the Odyssey doesn’t really work with my Sony PVM. The picture rolls.

A rolling image from a pong console

Why is that? A fast have a look at the oscilloscope (I’ve a kind of now too! Wow I really feel like an actual content material creator) reveals that for some motive the frequency has dropped to 50Hz. This isn’t imagined to be PAL!

A yellow series of pulses, being timed at 50Hz

Adjusting it as much as 60Hz with the offered potentiometer didn’t appear to assist although. This can be a bizarre case the place the Framemeister did a greater job with a sign than an actual honest-to-goodness CRT! I by no means thought I’d see the day.

Framemeister status on top of a pong console. The frequency is 60Hz

Perhaps we should always discuss that sign, and see what’s so bizarre about it. Let’s take a better look. Proper now, the sport console is in Recreation A, which seems to be quite a bit like Pong Magnavox Odyssey Desk Tennis: two paddles, one ball, and a middle line.

Magnavox Odyssey 100 game mode A. Two paddles, a center line, and a square ball. That's all, folks

So what does the sign of this sport mode appear to be? Do not forget that the display screen is drawn one line at a time, in collection. There are a collection of “horizontal sync pulses” that mark the start of every new scanline, and goes into the area often called “blacker than black”, for the reason that voltage is decrease than the bottom seen shade.

Right here, we’re wanting proper across the vertical sync area. That is the place for a number of scanlines, the entire video sign goes into that “blacker than black” area. The horizontal sync pulses are actually inverted– lacking these pulses within the vertical sync area was one of many points that made Dottori-kun a ache to get video output from.

Oscilloscope trace showing the signal

That is fairly typical of a monochrome video sign; there’s no “shade burst” or any excessive frequency indicators to complicate the image. Nonetheless, discover that every scanline that’s seen has the excessive slender pulse that signifies the white central line; in most sport techniques, the area across the vertical sync pulse, often called the “vertical blanking interval”, has no strains displayed.

Right here’s what that appears like on my Panasonic FS-A1F MSX machine; observe that what may appear to be indicators are the colour burst, which stays on every line besides throughout the vertical sync pulse itself.

Oscilloscope trace showing a different signal, with blank lines around a vertical sync pulse

Let’s check out the very starting of the vertical sync area. High is the Magnavox Odyssey 100, and the underside is the MSX sign. (A bit distorted as I took the hint on the unsuitable frequency, however don’t thoughts that)

Oscilloscope traces. An odd artifact is seen

Discover the bizarre timing of the sign; it’s nearly just like the vertical sync interval began in the midst of a horizontal sync. And that’s precisely that occurred. In spite of everything, did you discover that on the Odyssey 100’s board, there are two totally different changes for horizontal and vertical timing?

The cardboard cover for the Odyssey 100, showing HORIZ FREQ and VERT FREQ as different adjustments

See Also

That may make sense on the again of your TV, but it surely doesn’t make sense for one thing that produces a sign. Usually, it might have a single oscillator, and it might know what number of horizontal strains it created. You don’t want a CPU to do that; a easy counter IC would just do as effectively.

However the 1972 Magnavox Odyssey (the unique) didn’t have any ICs. And fairly than construct a counter of collection of particular person transistors, Baer took an easier method: the horizontal and vertical sync pulses are generated by two utterly separate astable multivibrator circuits. Which is to say, the Magnavox Odyssey isn’t only a pre-CPU console. It’s downright analog.

Odyssey sync generator.

Check out the service manual; the 2 are totally different circuits that don’t work together. Whereas the Magnavox Odyssey 100 does consolidate the circuits right into a single chip (IC1, which additionally consists of the voltage regulator, considerably unusually), it retains separate oscillators for vertical and horizontal. It actually is usually only a consolidation of the unique Odyssey.


I advised you that the Odyssey 100 was a stripped down Magnavox Odyssey. And in some ways in which’s true. It has no overlays, ditches the indifferent wired controllers, the sunshine gun, and the choice for various behavioral playing cards. Nonetheless, it does refine the gameplay of Odyssey Desk Tennis.

However to elucidate this, first now we have to take a look at Odyssey Desk Tennis. It was, in keeping with a courtroom of regulation, the inspiration and origination for the well-known Atari sport Pong. Nonetheless, the 2 are literally from a participant’s perspective very totally different video games.

Pong gameplay on the real cabinet
Picture from Wikimedia Commons

I’m not speaking about options like on-screen scoring, however precise gameplay. In Pong, you utilize a single potentiometer to maneuver vertically on a playfield. Your horizontal place is fastened. The ball ricochets off your paddle, with the angle altering relying on the place in your paddle the ball hit. (This gameplay characteristic is named a “segmented paddle”) The ball bounces off of the highest and backside of the display screen, and the sport performs sound results when the ball bounces.

What about on the Odyssey?

Manual photos explaining a ball bouncing off the paddle

The Magnavox Odyssey has no beeps; the console is silent. You employ two potentiometers to maneuver horizontally and vertically. Moreover, you’ve a 3rd potentiometer, referred to as the “English”. After the ball hits your paddle, you should use the “English” to regulate the vertical motion of the ball whereas it bounces again. For those who transfer it off the highest or backside of the display screen, that’s a you downside, and the Odyssey guide calls it a foul. For those who transfer it previous the opposing participant’s aspect of the display screen, you get some extent. Press the reset button and begin once more.

The “English” potentiometer, so named as a result of it simulates “placing somewhat English on the ball” (doubtlessly simply an American phrase? It refers to placing spin on the ball to vary its trajectory), is essential to the gameplay of Desk Tennis. Pong doesn’t have this ingredient due to the segmented paddle, however on the Odyssey with out the English knob, the ball will at all times bounce horizontally, which isn’t a really enjoyable sport.

The ball bouncing horizontally

Recreation A on the Magnavox Odyssey 100 is a slight refinement of Odyssey Desk Tennis, with just some variations, in addition to having the controls moved to the system housing.

  1. The ball can not be moved out of the highest or backside of the play space. A “rebound” circuit will take over and block makes an attempt so as to add an excessive amount of “English”.
  2. The ball now serves mechanically when the ball is off-screen, and the serving participant strikes their paddle to overlap the white vertical middle line. You not serve the ball by resetting the console.
  3. The paddles are actually vertical, not squares.
  4. A speaker beeps once you hit issues with the ball.

Numbers 1 and a pair of have been required by the Odyssey 200, which incorporates a primitive type of on-screen scrolling, so that you couldn’t be continually resetting issues; it was good of them to be included on the Odyssey 100 as effectively. As for numbers 3 and 4, effectively, if Magnavox did borrow some inspiration from Pong, it’s simply honest turnabout.

The place the Odyssey 100 actually goes past the naked minimal, although, is Recreation B.

Game B. Two vertical lines have narrow gaps

On this sport mode, the middle line turns into your leftmost aim (fortunately, a handy potentiometer lets you transfer it to the left aspect) and a brand new proper line seems. Not like in Recreation A, the ball now interacts with these strains; one draw back of this sport mode is that it’s a bit complicated who can use “English” after the ball bounces off a wall. The unique Odyssey had nothing similar to this sport mode.

As a result of that is nonetheless an Odyssey, and an analog online game console, the positions of the gaps within the objectives are managed by a potentiometer on the circuitboard. Above, I tuned the aim positions when the Odyssey 100 was nonetheless operating at 50Hz, so after I fastened it to run at 60Hz, they all of a sudden grew to become too low.

Game B. The goal is slightly too low

General the Magnavox Odyssey 100 might be not probably the most fascinating console on the earth. It’s in all probability not probably the most enjoyable console on the earth. However its circuitboard may be very mind-blowing in a selected approach. Usually in online game {hardware}, one factor you be taught shortly is that one thing like Truxton isn’t going to have, say, a “participant” chip or a “bullet” chip. Gameplay components the participant sees are constructed out of much more base options of the {hardware}, like sprites and tilemaps. However check out the Odyssey 100’s service guide:

List of the basic functions of each chip


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