I really want to see someone get Doom running in Emacs. I’ve tried to figure out if anyone has but of course what actually comes up is “Doom Emacs” which is a specifically customized version of it.
It means that all the code is running in privileged kernel mode instead of user mode. Kernel mode is usually reserved for the operating system and device drivers only. If code running in kernel mode has an unhandled exception or error, the entire system will crash. This creates the BSOD or “blue screen of death” on Windows.
User mode is less privileged and where all your typical applications run. If something crashes in user mode, it only crashes that process, not the whole system.
It’s a crazy thing that they did. Very impressive technically, but not really useful.
Forgive me if this is a stupid question but why is it technically impressive? Is it not just the same as running it in usermode but with higher privileges?
The API is much more limited for kernel mode, because Microsoft doesn’t want to make it easy to crash the kernel. So it’s not just a matter of taking old DOS code and making Windows run it in an old compatibility layer, but actually requires translating the whole thing into a much more limited set of commands to properly draw the graphics and respond to user input.
It’s impressive like being able to play the French horn without using the valves, or painting beautiful pictures using only a mechanical typewriter. It’s being able to do something that is trivially easy with normal tools, but with such a limited toolset that the accomplishment itself is impressive.
It’s not just about being DOOM players. It’s a long running joke in the programming and engineering world. Wether it’s a fridge, a toaster, a decommissioned 1970s super computer… can it run DOOM?
The main reasons why it’s Doom specifically are also because:
The game is open-source: github.com/id-Software/DOOM/pulls?q=is%3Aopen+is%… This makes it much more doable to port it to other platforms (and to strip out anything not absolutely required to get the first level to run when you run into technological limitations) than when you have to rely on unofficial modding tools.
It’s nearly 30 years old and designed for computers with only a few megabytes of memory and for processors of well under 100MHz, which are specs which the majority of modern systems have, even embedded systems. It also renders fully on the CPU and doesn’t require specific hardware like a GPU or a specific graphics chip.
Being a first person shooter with 3D-ish visuals it looks a lot more impressive than if you show off a simple game like Pong orTetris or something like that. It has the right balance between performance requirements and impressiveness, and it’s also a game that was very popular in its time and it’s instantly recognisable to a lot of people.
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