Graphics in Arcade Games, 1972 - 1977

Before I continue with my exploration of early '80s gaming, I want to take a step backwards and talk in more detail about the graphical capabilities of the early arcade machines, because they give context for what's coming.

Discrete Circuits

The first wave of arcade games were designed without microprocessors, so any graphical information had to be a product of the logic of the internal circuitry.  Indeed, the two most famous games from this era, Pong (1972) and Breakout (1976), had graphics that consisted entirely of squares and rectangles.

Animation simultaneously showing the original arcade versions of Pong and Breakout.  Captured from DICE.

The Pong ball and paddle were nothing more than short segments of lines in the video signal, while the digits representing the scores were made up of paddle-like objects in various configurations.  In addition, very few of these early arcade machines could project color onto the monitor, so color was often added artificially using cellophane overlays.  This is why you see the color laid out in horizontal strips on early games like Breakout and Space Invaders.  Emulators usually reproduce the color as if it were overlaid on your monitor, but the actual output from the hardware was in black-and-white.

Graphic design is an essential part of the modern gaming landscape, but in the early days, designers paid a heavy toll for making the graphics too complex.  A particularly extreme case is shown below.

Animation of arcade game Space Race 1973 alongside of a portion of the circuit board.  The shape of the spaceship created from diodes.

This is 1973's Space Race.  In order to create the spaceship shape on the screen, they had to lay out a diode for each point in the graphic, like a bitmap soldered into the circuit board.  Even considering that they only needed half of the spacecraft (the other half is a mirror image), the diode map takes up a lot of physical space.  Perhaps as a result of this, the game is incredibly facile, with the spaceship doing nothing but dodging random dots to get to the other side of the screen.  Space Race was a commercial flop, demonstrating very early on how you can't use graphics as a substitute for gameplay.

Another interesting case from the pre-microprocessor era is Hi-Way (1975):

Animation of the arcade game Hi-way 1975 alongside the distorted car sprite.

Here, the cars are still just collections of rectangles, but the designers added an interesting twist, both figuratively and literally.  When a car turns in response to road curves, the machine adds line-by-line delays to the screen draw, causing the car to distort in the direction of motion.  The resulting gameplay is a bit surreal -- distortions aren't exactly the same as rotations -- but mostly achieves its goal.

The Introduction of Read-Only Memory Units (ROMs)

It's clear that video games needed a more compact storage device if they were going represent complex images on the screen. Enter read-only memory, or ROM.

Using ROM, video game manufacturers could program sprites into a compact solid state device rather than a set of diodes on the circuit board.  The information in the ROM could then be read out and converted for display on the monitor.  As early as 1974, arcade game manufacturers were taking advantage of ROM to store sprites for their games.



In Shark Jaws (1975), Atari used ROM to hold animated images of a diver, a fish, and a shark.  Alternating sprites suggested the swimming action, while a slightly more complex animation was used to animate the shark's chomp.  The game was still being powered by a discrete integrated circuit, however, so the gameplay was limited to what could be easily achieved with discrete logic.  For example, the shark opens and closes its mouth at random times and the diver just disappears when he's "eaten".

Shark Jaws had some success, most likely due to the unlicensed tie-in to Jaws, but was still severely limited.  If games were going to take the next step in complexity, it wasn't enough to just store complex graphical data, they also needed something that could quickly process manipulations to it.

Microprocessors

Nothing demonstrates the significance of the microprocessor transition better than Taito's Western Gun (1975), which was originally designed and released in Japan with discrete components only.  This is what the player interactions looked like on initial release:

Animation of video clip showing arcade game Western Gun 1975.  Two blocky cowboys fire at each other across a cactus and rock.

When Midway decided to pick the game up for release in the USA, they completely redesigned it using an 8080 microprocessor (and renamed it to Gun Fight):

Animation of arcade game Gun Fight 1975, with three cowboy animations shown on the side.  Sprite animations include walking, death, and aiming.

No longer are the character animations constrained to large blocks and image distortions.  Instead, distinct sprites are used to animate each part of the action.  Notice how the two sprites used in the walking motion are different across their entire length, mimicking the full-body changes that occur when a person shifts their weight from one leg to the next.  That level of detail would have been extremely difficult to achieve with discrete circuit components in a standard arcade cabinet.  Also impressive is the death animation which, rather than switching between two ambiguous and blocky images, animates the cowboy's fall to the ground with three distinct frames.

These graphics are impressive for 1975.  Of course, it probably helped that there was little more to the game than two cowboys walking around shooting at each other, but it was a milestone nevertheless.  The Japanese designer of Western Gun, Tomohiro Nishikado, was so impressed by the visual appearance of Midway's conversion that he would use the same 8080 microprocessor in Space Invaders two years later.

Exidy's Circus (1977), which I covered in an earlier entry, was another example of what was possible with a CPU-driven arcade machine.

Animation of arcade game Circus (1975), with clown animations shown on the side.  Sprite animations include jumping, walking, and death.

The circus backdrop, including the moving balloons, is all produced from random access memory (RAM), while the circus clown image is continuously retrieved from ROM based on internal counters that keep track of position and rotation.  Recomputing the clown sprite on the fly would have been prohibitive for the hardware of the time, so Circus had a memory unit devoted entirely to the bouncing clown's image.  This is a common problem in the manipulation of complex graphics, so dedicated sprite hardware would be a standard component of both arcade and home video game systems for over a decade to come.

Technological changes would continue to drive improvements in the graphical capabilities of arcade machines, but the question of how to spend your limited resources remained.  The biggest hits of the next few years, including Space Invaders and Pac-Man, typically used less complex animations than either Gun Fight or Circus, but were more complex games in other respects.  

Continued in Part 2.

Comments

  1. I find Sega's Monaco GP to be particularly fascinating. Released in 1979, its TTL-based circuitry was long obsolete, but may just be the most sophisticated CPU-less video game ever made. Multiple color sprites, fast-scrolling graphics, headlight effects, different terrain types, and even a weird zooming animation. It would be moderately fancy by 1982 standards. And Nurburgring 1 of 1975 is an obvious predecessor to Night Driver, and managed pseudo-3D first person racing only with discrete circuits. It almost certainly will never be emulated - even video footage would be a holy grail.

    "Notice how the two sprites used in the walking motion are different across their entire length, mimicking the full-body changes that occur when a person shifts their weight from one leg to the next."

    TBH, I'm not really sure how that's different from what Shark Jaws is doing with its multiple sprite frames in ROM. But one thing that is different is how the cowboys' gun-arms are animated independently of their bodies.

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    1. It’s a good question how much of Gun Fight could have been done with discrete components + ROM. Nishikado was apparently convinced that the microprocessor was the key (and I’m inclined to bow to his more direct experience), but Shark Jaws does seem to suggest you can do a lot with sprites by just adding ROM.

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