eli5 How are people playing Doom on so many different (and usually very old) devices? A notepad, pregnancy test, how tf?

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Like how tf does one play Doom on a pregnancy test???????

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22 Answers

Anonymous 0 Comments

The Notepad one is simple, use a converter that transforms the actual graphics into ASCII text (for instance, VLC has a plugin which does it), then pastes the text into Notepad. Notepad has no way of running an executable inside itself.

The pregnancy test one is even simpler, [they just replaced the guts with a better display and microcontroller.](https://www.pcmag.com/news/yes-doom-is-playable-on-a-pregnancy-test) Funny for the memes, not an actual demonstration of computing power. Pregnancy tests are meant to be disposable and simply check for a hormone level, they don’t need a fancy display and processer which would jack up the price.

Anonymous 0 Comments

> Like how tf does one play Doom on a pregnancy test???????

In this particular case by replacing the CPU inside the device with one capable of running Doom.

Doom was released in 1993 on MS DOS. It requires like 4mb of memory and was built to run on a processor orders of magnitude slower than even the ones that show up in cheap, handheld electronics these days. Getting these devices to run Doom is generally much more about getting access to the device’s memory and processor to program it and figuring out how to work around the weirdness of the hardware (e.g., a pregnancy test’s tiny screen) than about figuring out how to run Doom efficiently.

Anonymous 0 Comments

Note, the pregnancy one wasn’t actually on a pregnancy test, but let’s pretend it was on some “smart” pregnancy test device.

Computers are computers. Doesn’t matter if they are a laptop, desktop, camera, fridge, tablet, pregnancy test. If its got electronics that can compute, kt can compute anything. To interact with the computer, we as humams use things called shells, you are likely familiar with operating systems like windows, linux, or macos, but phones and tablets have android or ios, and cameras/iot devices have their own os on them. These more specialized operating systems are designed to do the thing their device is designed for an nothing else. The developers of these operating systems do not let you install other programs on to the device like you can on a windows computer. There’s no need to. (sometimes cameras or other devices might have their own app store like the play store or app store on Apple) But, underneath that specialty operating system is still a computer that just understands ones and zeroes, it really doesn’t care if it computes photos, pregnancy results, or doom. So people will find vulnerabilities in the device to exploit and put their own operating system on the device, one that can run doom. They might need to tinker with the operating system a bit so that it looks for the devices screen and buttons (since it might be looking for a typical monitor and keyboard for example) , but if the official camera operating system can recognize what to do when a button is pressed, there’s no reason that this new operating system can’t be written do the same.

TLDR: The computer underneath these devices doesn’t care about what they are computing, whether that be doom, or anything else. To it, it’s just following instructions. The hard part is finding a way to send new instructions to the computer as manufacturers intentionally lock the “doors” to the computer or just dont put a “door” in at all.

Anonymous 0 Comments

Doom’s engine is unique in the sense that its incredibly well documented,due ot being open source for a LONG TIME with a very active modding comumnity+ being very lean in compneoents and resources(you dont even need a GPU because the engines inplmements software rendering).

this in turns allows especially brave enthisiasts and programmers to effectively port the engine into devices that you wouldnt think can run it.

Anonymous 0 Comments

Doom can run on a Raspberry Pi Zero which costs $15. It’s a tiny general purpose computer with a processor, memory, ports and very basic version of Linux.

Maybe a smart fridge could get away with half the memory and only one port, but at $15 it’s cheaper to buy an overpowered chip than develop something in house.

The Raspberry Pi is aimed more at hobbyists, but there are hundreds of companies making similar mini computers for manufacturers.

Anonymous 0 Comments

You can also play it in a cardboard box. Just get a box, cut a hole and put a computer/monitor/tablet/phone inside with the screen facing out the hole.

Anonymous 0 Comments

most of them, very few run it on the actual hardware.

i’ve seen a ton of these ‘play doom on it’ where the device’s ‘monitor’ is just that….it’s using a raspberry pi connected to it as a monitor, nothing more.

Anonymous 0 Comments

There are a lot of good responses. It is important to note that back when Doom was written, the hardware was pretty weak compared to today. Just like the remarks about landing on the moon with less computing power than a modern calculator, Doom requires little power compared to what we have today.

Additionally, during this period of computing history, developers coded their games and applications with significantly less overhead than we have today. Developers still need to code today, but much of the code is written using development platforms to make it easier and more powerful. This requires greater overhead than if you wrote all your own code from scratch.

So you have a game, with a familiar playstyle (as one of the first FPS games), optimized, and old. That means that it can run on things that have no business running a FPS game. (Even if it is just using the device for a display).

Anonymous 0 Comments

A pregnancy test might seem crazy. But you haven’t seen anything until you’ve seen Quake running on an analogue [Oscilloscope ](http://www.lofibucket.com/articles/oscilloscope_quake.html)

Anonymous 0 Comments

I’ll do you one better; WHY is everyone playing Doom on so many different devices?