Collapse OS is an interesting project whose goal is to build an open source operating system designed to work with ubiquitous and easily scavenged electronic components in a post-apocalyptic Fallout-like future where consumer electronics might be a thing of the past (as global supply chains, among other things, collapse). The project's creator, software developer Virgil Dupras, Collapse OS is what people in a possible/potential future-to-be will need to re-configure and retrofit scavenged smartphones, devices and computer parts and components into something functional and usable. In such a scenario as Dupras envisions, populations will not be able to produce mass electronics any more, but they'll still nonetheless be an enormous source of political and social power, giving anyone capable of scavenging and re-programming electronics a significant advantage over those who aren't.

Or as Dupras puts it:

I expect our global supply chain to collapse before we reach 2030. With this collapse, we won't be able to produce most of our electronics because it depends on a very complex supply chain that we won't be able to achieve again for decades (ever?).

This will usher a new age of scavenger electronics: parts can't be manufactured any more, but we have billions of parts lying around. Those who can manage to create new designs from those parts with low-tech tools will be very powerful.

Also clarifying that it's only applicable in a certain range of collapse-severity:

This project is only relevant if the collapse is of a specific magnitude. A weak-enough collapse and it's useless (just a few fabs that close down, a few wars here and there, hunger, disease, but people are nevertheless able to maintain current technology levels). A big enough collapse and it's even more useless (who needs microcontrollers when you're running away from cannibals).

But if the collapse magnitude is right, then this project will change the course of our history, which makes it worth trying.

This idea is also fragile because it might not be feasible. It's difficult to predict post-collapse conditions, so the "self-contained" part might fail and prove useless to many post-collapse communities.

But nevertheless, this idea seems too powerful to not try it. And even if it proves futile, it's a lot of fun to try.

What had motivated/inspired the project of Collapse OS, Dupras claims, had been the work/writings of Pablo Servigne — which are all in French, but a talk with English subtitles is available here. 

At a certain moment in time, some people chose the combustion engine to develop civilization. And now we spend our time solving that problem. Sociologists call it "path dependence". We're stuck in a rut, each time we have to improve our situation, but it depends on the past generations' technical choices. This is a socio-technical system, and this socio-technical system is gigantic, it is worldwide. The bigger it is, the more locked it is. We have a lot of difficulty to come out of that track, to turn the steering wheel and start the transition towards another society, another civilization, etc. The bigger it is, the more locked it is, the more political locks, cognitive locks there are, etc. This is an enormous challenge.

- Pablo Servigne  

Collapse OS works with Z80 (Zilog Z80) 8-bit microprocessors which, though less common today than other 16- and 32-bit components, can still be found in things like cash registers, calculators, musical instruments and synthesizers, coin operated arcade games and other embedded systems. The Z80 was launched in 1976 as extension and improvement on the Intel 8080, but also became one of the most widely used CPUs for desktops and home computers too between the 1970s to mid-1980s. In a Reddit Q&A, Dupras explained that the Z80 was chosen "because it's been in production for so long and because it's been used in so many machines, scavenger have good chances of getting their hands on it." Even more importantly, Z80s are simple enough to grok and wire by hand, so if one were stripping components for a make-shift computer in a post-apocalyptic world, the Z80 would be one of the first candidates.

Collapse OS is extremely low-tech, written in low-level assembler (.asm files) and has a shell that can poke and call arbitrary code from memory, I/O, a text editor modeled after ed in UNIX, is built from a POSIX (family of standards for maintaining compatibility between operating systems) environment with minimal tooling (only libz80 is needed). A set of emulators running Collapse OS in different contexts in-browser is available here. The roadmap describes the goal and point of the exercise:

Minimal systems? There's tons of them. Self-assembling systems? There's tons of them. Running on less than 10K transistors? not so much.

If we assume that lower complexity will be forced upon us, we need such a system, a system that is capable of running and self-replicating on very low transistor count.

Collapse OS has no target machine because those machines it's going to run on don't exist yet and will very often be cobbled up together. However, it has target specs, inspired by Grant Searle's minimal z80 computer: it should run and self-replicate on 8K of ROM and 56K of RAM.

Anything bigger starts being much more complex because you need memory paging, and if you need paging, then you need a kernel that helps you manage that, etc.. Of course, I don't mean that these more complex computers can't be built post-collapse, but that if we don't have a low-enough bar, we reduce the likeliness for a given community to bootstrap itself using Collapse OS.

Dupras has said he's satisfied with the project’s progress. “I think I could finish it by myself, but I thought it would be more fun to do with a couple of other developers,” he has said. “Participation requires a very specific set of inclinations (believing in collapse) and skills (electronics and z80 assembly). I think that very few people fitting those requirements exist. But if they do, I'd like to find them.”

Vice have also written about Collapse OS. Full documentation is available here. And an interesting, informative discussion thread on ycombinator's hackernews can be found here.

A demo of Collapse OS.