221 lines
10 KiB
Markdown
221 lines
10 KiB
Markdown
# Collapse OS
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*Bootstrap post-collapse technology*
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Collapse OS is a z80 kernel and a collection of programs, tools and
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documentation that allows you to assemble an OS that can:
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1. Run on an extremely minimal and improvised architecture.
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2. Communicate through a improvised serial interface linked to some kind of
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improvised terminal.
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3. Edit text files.
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4. Compile assembler source files for a wide range of MCUs and CPUs.
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5. Write files to a wide range of flash ICs and MCUs.
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6. Access data storage from improvised systems.
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7. Replicate itself.
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Additionally, the goal of this project is to be as self-contained as possible.
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With a copy of this project, a capable and creative person should be able to
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manage to build and install Collapse OS without external resources (i.e.
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internet) on a machine of her design, built from scavenged parts with low-tech
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tools.
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## Status
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The project is progressing well! Highlights:
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* Has a shell that can poke memory, I/O, call arbitrary code from memory.
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* Can "upload" code from serial link into memory and execute it.
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* Can manage multiple "block devices"
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* Can read SD cards as block devices
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* A z80 assembler, written in z80 that is self-assembling and can assemble the
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whole project. 4K binary, uses less than 16K of memory to assemble the kernel
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or itself.
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* Extremely flexible: Kernel parts are written as loosely knit modules that
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are bound through glue code. This makes the kernel adaptable to many unforseen
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situations.
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* A typical kernel binary of less than 2K (but size vary wildly depending on
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parts you include).
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* Built with minimal tooling: only [libz80][libz80] is needed
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## Why?
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I expect our global supply chain to collapse before we reach 2030. With this
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collapse, we won't be able to produce most of our electronics because it
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depends on a very complex supply chain that we won't be able to achieve again
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for decades (ever?).
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The fast rate of progress we've seen since the advent of electronics happened
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in very specific conditions that won't be there post-collapse, so we can't hope
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to be able to bootstrap new electronic technology as fast we did without a good
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"starter kit" to help us do so.
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Electronics yield enormous power, a power that will give significant advantages
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to communities that manage to continue mastering it. This will usher a new age
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of *scavenger electronics*: parts can't be manufactured any more, but we have
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billions of parts lying around. Those who can manage to create new designs from
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those parts with low-tech tools will be very powerful.
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Among these scavenged parts are microcontrollers, which are especially powerful
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but need complex tools (often computers) to program them. Computers, after a
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couple of decades, will break down beyond repair and we won't be able to
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program microcontrollers any more.
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To avoid this fate, we need to have a system that can be designed from
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scavenged parts and program microcontrollers. We also need the generation of
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engineers that will follow us to be able to *create* new designs instead of
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inheriting a legacy of machines that they can't recreate and barely maintain.
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This is where Collapse OS comes in.
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## Goals
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On face value, goals outlined in the introduction don't seem very ambitious,
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that is, until we take the time to think about what kind of machines we are
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likely to be able to build from scavenged parts without access to (functional)
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modern technology.
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By "minimal machine" I mean [Grant Searle's minimal z80 computer][searle].
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This (admirably minimal and elegant) machine runs on 8k of ROM and 56k of RAM.
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Anything bigger starts being much more complex because you need memory paging,
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and if you need paging, then you need a kernel that helps you manage that,
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etc.. Of course, I don't mean that these more complex computers can't be built
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post-collapse, but that if we don't have a low-enough bar, we reduce the
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likeliness for a given community to bootstrap itself using Collape OS.
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Of course, with this kind of specs, a C compiler is out of the question. Even
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full-fledged assembler is beginning to stretch the machine's ressources. The
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assembler having to be written in assembler (to be self-replicating), we need
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to design a watered-down version of our modern full-fledged assembler
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languages.
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But with assemblers, a text editor and a way to write data to flash, you have
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enough to steadily improve your technological situation, build more
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sophisticated machines from more sophisticated scavenged parts and, who knows,
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in a couple of decades, build a new IC fab (or bring an old one back to life).
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## Organisation of this repository
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There's very little done so far, but here's how it's organized:
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* `kernel`: Pieces of code to be assembled by the user into a kernel.
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* `apps`: Pieces of code to be assembled into "userspace" application.
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* `recipes`: collection of recipes that assemble parts together on a specific
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machine.
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* `doc`: User guide for when you've successfully installed Collapse OS.
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* `tools`: Tools for working with Collapse OS from "modern" environments. Mostly
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development tools, but also contains emulated zasm, which is
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necessary to build Collapse OS from a non-Collapse OS machine.
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Each folder has a README with more details.
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## Roadmap
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The roadmap used to be really hazy, but with the first big goal (that was to
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have a self-assembling system) reached, the feasability of the project is much
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more likely and the horizon is clearing out.
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As of now, that self-assembling system is hard to use outside of an emulated
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environment, so the first goal is to solidify what I have.
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1. Error out gracefully in ZASM. It can compile almost any valid code that scas
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can, but it has undfined behavior on invalid code and that make it very hard
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to use.
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2. Make shell, CFS, etc. convenient enough to use so that I can easily assemble
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code on an SD card and write the binary to that same SD card from within a
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RC2014.
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After that, then it's the longer term goals:
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1. Get out of the serial link: develop display drivers for a vga output card
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that I have still to cobble up together, then develop input driver for some
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kind of PS/2 interface card I'll have to cobble up together.
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2. Add support for writing to flash/eeprom from the RC2014.
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3. Add support for floppy storage.
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4. Add support for all-RAM systems through bootloading from storage.
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Then comes the even longer term goals, that is, widen support for all kind of
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machines and peripherals. It's worth mentionning, however, that supporting
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*specific* peripherals isn't on the roadmap. There's too many of them out there
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and most peripheral post-collapse will be cobbled-up together anyway.
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The goal is to give good starting point for as many *types* of peripherals
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possible.
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It's also important to keep in mind that the goal of this OS is to program
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microcontrollers, so the type of peripherals it needs to support is limited
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to whatever is needed to interact with storage, serial links, display and
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receive text, do bit banging.
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## Open questions
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### Futile?
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For now, this is nothing more than an idea, and a fragile one. This project is
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only relevant if the collapse is of a specific magnitude. A weak-enough
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collapse and it's useless (just a few fabs that close down, a few wars here and
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there, hunger, disease, but people are nevertheless able to maintain current
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technology levels). A big enough collapse and it's even more useless (who needs
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microcontrollers when you're running away from cannibals).
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But if the collapse magnitude is right, then this project will change the
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course of our history, which makes it worth trying.
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This idea is also fragile because it might not be feasible. It's also difficult
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to predict post-collapse conditions, so the "self-contained" part might fail
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and prove useless to many post-collapse communities.
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But nevertheless, this idea seems too powerful to not try it. And even if it
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proves futile, it sounds like a lot of fun to try.
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### 32-bit? 16-bit?
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Why go as far as 8-bit machines? There are some 32-bit ARM chips around that
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are protoboard-friendly.
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First, because I think there are more scavenge-friendly 8-bit chips around than
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scavenge-friendly 16-bit or 32-bit chips.
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Second, because those chips will be easier to replicate in a post-collapse fab.
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The z80 has 9000 transistors. 9000! Compared to the millions we have in any
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modern CPU, that's nothing! If the first chips we're able to create
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post-collapse have a low transistor count, we might as well design a system
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that works well on simpler chips.
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That being said, nothing stops the project from including the capability of
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programming an ARM or RISC-V chip.
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### Prior art
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I've spent some time doing software archeology and see if something that was
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already made could be used. There are some really nice and well-made programs
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out there, such as CP/M, but as far as I know (please, let me know if I'm wrong,
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I don't know this world very well), these old OS weren't made to be
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self-replicating. CP/M is now open source, but I don't think we can recompile
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CP/M from CP/M.
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Then comes the idea of piggy-backing from an existing BASIC interpreter and
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make a shell out of it. Interesting idea, and using Grant Searle's modified
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nascom basic would be a good starting point, but I see two problems with this.
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First, the interpreter is already 8k. That's a lot. Second, it's
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copyright-ladden (by Searle *and* Microsoft) and can't be licensed as open
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source.
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Nah, maybe I'm working needlessly, but I'll start from scratch. But if someone
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has a hint about useful prior art, please let me know.
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### Risking ridicule
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Why publish this hazy roadmap now and risk ridicule? Because I'm confident
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enough that I want to pour significant efforts into this in the next few years
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and because I have the intuition that it's feasible. I'm looking for early
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feedback and possibly collaboration. I don't have a formal electronic training,
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all my knowledge and experience come from fiddling as a hobbyist. If feasible
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and relevant (who knows, IPCC might tell us in 10 years "good job, humans!
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we've been up to the challenge! We've solved climate change!". Does this idea
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sound more or less crazy to you than what you've been reading in this text so
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far?), I will probably need help to pull this off.
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[searle]: http://searle.hostei.com/grant/z80/SimpleZ80.html
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[libz80]: https://github.com/ggambetta/libz80
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