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https://github.com/schierlm/collapseos-uxn

Port of CollapseOS to uxn Tal
https://github.com/schierlm/collapseos-uxn

collapse-os uxn uxntal

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Port of CollapseOS to uxn Tal

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# collapseos-uxn



Port of CollapseOS to uxn Tal



## Description



This is a port of [Collapse OS](http://collapseos.org/) (Snapshot 2022-05-09) to the

[uxn](https://100r.co/site/uxn.html)/[varvara](https://wiki.xxiivv.com/site/varvara.html)

virtual machine.



Unlike other Collapse OS ports, it does not try to assemble the whole rom image

using Collapse OS Forth. Instead it uses a two-step approach.



The core image of the OS is assambled using [uxntal](https://wiki.xxiivv.com/site/uxntal.html),

and will dynamically load a forth image from `collapseos.bin` at `$0800`, overwriting the

initialization code that resided at that place previously. As uxntal is self-hosting on UXN,

this shortcut was deemed acceptable to me. The tooling for uxntal in VS Code as well as UXN32

debugger support made porting definitely faster for me that way. Also, the ISA/ABI is unstable

enough to require three different uxnasm builds to compile for three different emulators, so

building an assembler written in Forth is just not an option for me.



Also note that the port was started at the CVM port and only implements the bare minimum

of native words - first make it work, then make it faster.



I was considering to use the native operand and return stack for the Forth operand and return

stack, but ultimately decided against it. The event-driven nature of keyboard input would

have required the `(key)` word to unwind the stack and store it elsewhere, and later restore

once a key is pressed or the timer interrupt vector fires.



Therefore, like most other ports, the Forth operand and return stack live in normal system memory;

the stack pointers live in the zero page among other global variables.



There are two versions. The normal version supports a block filesystem which may either exist as

a single file named `blkfs`, or multiple files named `blk0000` to `blk9999`. At first startup

the former file is converted to the latter form and then deleted. This design choice was driven

by the fact that when *writing* files on varvara, there is no way to seek. Therefore writing each

block into a separate file gets away with that limitation easily.



The second, *lite* version does not support block filesystems, and does not require filesystem

access. To use, you have to concatenate the forth image file to the core image file (which is `$0700`

bytes long, making the forth image end up at `$0800`).



It has been tested in the latest version of the UXN32 emulator (2022-04-26).



## Download



Have a look in the file release section if you want to download binaries to try.



## License



GPL3, just like Collapse OS



## Moving forward



Feel free to adopt this project if you find it interesting. I will follow Virgil's route and not update this project regularly.

(The fact that there are different incompatible versions of uxn images, without even a version number for them, and some emulators

get updated and some do not, has deterred me from keeping this up to date.)