Cathode-ray Tube Amusement Device Simulator

Cathode Ray Amusement Device Simulator

Cathode-Ray Tube Amusement Device Simulator (CRADS)

To play the Cathode-Ray Tube Amusement Device Simulator (CRADS), drag the planes and ships across the radar screen until they're in positions that you wish to target. When you're satisfied with their configuration, press the silver button at the top of the panel to start firing at them. You then have 30 seconds to adjust the "Trajectory" and "Blast Time" knobs so that the blasts detonate at the locations of the targets.

Just as in the original game, the device has no way of knowing when you hit the targets, so you have to make your own judgement about whether or not you've been successful. In order to hit your targets, you'll probably need to adjust the trajectory and blast time, which are controlled with the top four dials (see below for details on the controls). You can also control the size of your shells, the size of the blast, and the brightness of your shots as they appear on the screen.

Note that CRADS is designed to come as close as possible to the device described in the 1947 Goldsmith-Mann patent.

History of CRADS and the Original Goldsmith-Mann Game

The cathode-ray tube amusement device has an interesting place in video game histories, in that it's frequently mentioned at the beginning, but is generally not considered to be a video game. There are many conflicting accounts of its capabilities and the only visual aids provided by most sources are the circuit diagrams from the patent. I wasn't very satisfied with this state of things, so I decided to make CRADS to provide people both a visual and an interactive demonstration of what Goldsmith and Mann proposed in 1947.

Development of the original game was led by Thomas T. Goldsmith Jr., an engineer working for DuMont laboratories. DuMont was primarily a television broadcaster and a manufacturer of television-related equipment, but they also did research on general cathode-ray tube applications. Goldsmith's amusement device was intended to demonstrate the commercial possibilities of cathode-ray tube technology beyond television, but it never went into commercial production.

Most of what's known about the device is encoded in a five-page patent application by Goldsmith and his collaborator, Estle Ray Mann. A handmade prototype was made, presumably for demonstration at DuMont, but I did not find any detailed descriptions of it, so I used the patent as the primary source for designing CRADS.

The Display

There is no footage, or even photographs, of what the game's display looked like, but the patent clearly describes the use of a cathode-ray tube being impacted by a narrow electron beam. If you look at footage of action games from the '50s and '60s, like Tennis for Two or Spacewar!, you'll see they tend to have a lot of image persistence. It's likely that the cathode-ray tube amusement device had similar effects, so I've added a persistence model to the CRADS display.
The persistence model is a stack of 300 images from previous frames that are all plotted at once. The brightness of each image depends on how far down the stack it is. When the beam is focused, I also add a steady decrease in image size, in order to model saturation effects.

The Control Panel

The hardest part of making CRADS was the controls. The patent application has a diagram showing how Goldsmith and Mann envisioned the layout of the controls, and the CRADS layout mirrors that diagram, but the relationship between the various knobs and the moving spot is not always clear. I'm not an electrical engineer and would not claim to understand everything in the circuit diagrams, but I did my best to dissect the patent application to determine the function of each knob. The details of this dissection are beyond the scope of the present article, but I may elaborate in a subsequent entry if there is interest.

The Goldsmith-Mann controls are not what one would call user-friendly. The trajectory knobs are attached to a common control, making them redundant with each other. The blast time knobs are not attached to a common control, but are used to adjust the same thing and could have been combined into a single knob. The blast size knobs do have different functions -- the left one controls the size of the undetonated shell and the right one controls that of the detonated shell -- but they have little to do with the gameplay and probably should have been left to the operator to configure. Likewise, the brightness control is analogous to a screen brightness adjuster on a TV set and has nothing to do with the game, per se.

It may be that the controls were intentionally made to look complex so as to give the player the feeling that they were operating a real radar system. It may also be that determining the function of the controls was part of the game. However, I think it's more likely that Goldsmith and Mann simply hadn't yet put much thought into gamifying their invention. The purpose of the patent, in this case, was to protect the technology behind the game, not its detailed mechanics.

Relationship to Subsequent Games

The Goldsmith-Mann device stands out among the early video game candidates because it wasn't produced as part of the nascent computing revolution, and was something of a technological dead end. Add this to the fact that it never went into widespread production, and it seems unlikely that it had much influence on subsequent game development.

Nevertheless, playing CRADS, I can't help thinking of how much it resembles the artillery duels that frequented early home computers and video game consoles. Those games simulated ballistic motion of a shell fired from a gun emplacement, where you would input an initial angle (and sometimes speed) to hit a target at a predetermined point.
Gameplay from 1982 game Artillery Duel, for the Astrocade console.
Unlike in artillery duels, the motion of the shells in CRADS do not attempt to follow real physical laws, but they do have you tune the initial parameters in order to hit a target.

Is It the First Video Game?

One reason I wanted to make CRADS was to give people an opportunity to judge for themselves whether or not they think it should qualify as a video game. I may give my own opinion in a later entry, but for now, just give it a try and feel free to drop comments with your thoughts on the question.


  1. Long hoped someone would do this. Nice one.

    For me it's forever a sort-of-video-game. Predating this would be muting the TV sound and ad-libbing your own sounds and words in attempt to entertain yourself/the people around you. That would be an earlier electronic Television game, with the rules set externally to the electronics.

    And that in turn has links to shadow puppetry in front of an electric light bulb. Earlier still.

    There's also "Spotlight Golf" which seems to be the first digital computer. This used a computer, and had a light-bulb display. Is that not the first electronic game with an illuminated electronic display? From the 1930s!

    The CRT Amusement Device is still an undeniable attempt to make a dedicated electronic game with a visual display. Christopher Strachey's Draughts seems to be the first conventional video game, that's undeniably pinned to what makes a modern video game (computer based with a versatile video display, and also in its favour one with sound and music).

    Hard to pin down these firsts!

  2. Great Work. For me i had always no real idea (from the patent description) how this game really works. In my understanding in thought it must be like a very early version of "Worms", but it doesn't fit exactly. So i think your simulation is very close and makes more sense for me. It is in fact an electronic game and per definition (because the output on a video device) it's could be also a video game in my opinion. But this is for sure very debatable.

  3. I want to hug you for doing this! Thank you so much :-)

  4. Thank you for doing this! I heard that there are packaged gaming emulators that include games with fixed displayes (simulators) with them, I think your recreation should qualify.


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