OpenBSD on the Sempron
When it comes to a modern portable Unix system, the choice is generally Linux, OpenBSD and NetBSD. I'm not counting FreeBSD as it's heavier than the other two and more of a server OS in my opinion.
As we have already seen, this old relic of a computer can boot a modern Linux distro, at least terminal-only. Graphical Linux tends to be more RAM-hungry though in my experience, unless you take a lot of steps to optimize the RAM usage.
OpenBSD and NetBSD are simple Unix systems which have changed over time a lot less than Linux, to the point of still supporting floppy installation, unlike most Linux distros. In my experience, they are some of the smallest "full-fledged" modern Unix systems too, which is great for old computers! There are smaller systems like ELKS which runs in 640 KB of RAM, but they're more limited in software support and more ways.
The BSD systems are a lot less popular than Linux though and have less software/hardware support - it's very likely I'll try Linux on this machine too. However, at the time I'm writing this, Linux is ending support for the 486, which is a sign that using Linux on old computers will get harder and harder.
This computer has a 64-bit CPU, so why not install 64-bit OpenBSD? I downloaded the ISO from the OpenBSD website, burned it onto a DVD and tried to boot from it. The ISO is a bit over 700 MB, so some CDs will be too small for it.
Unfortunately, the system froze while loading the network driver. I thought that it might expect some newer CPU instructions and decided to try the 32-bit version.
The 32-bit version booted up all the way to the installer! Maybe the 64 bit version will be able to boot with a custom kernel and some patches, but for now I'm going with the 32-bit one. It might use less RAM too (I don't think OpenBSD uses x32 ABI).
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Boot flag preparation
Before installing though, we need to set the boot flag on the OpenBSD partition so that it gets detected properly by the installer.
To do that, we boot the PC with any Linux ISO (I used Arch just like in part 1), then use the "a" command in fdisk to set the boot flag on the OpenBSD partition. I explained fdisk usage in more detail in part 1.
After this, let's reboot, put the OpenBSD disc back in and get to the installation!
OpenBSD network setup
OpenBSD's installer has an old-looking, but surprisingly straightforawrd command line interface:
Welcome to the OpenBSD 7.6 installation program (I)nstall, (U)pgrade, (A)utoinstall or (S)hell?
First, we type "i" to begin installing the system. The installer will ask for a keyboard layout and then for a hostname:
Choose your keyboard layout ('?' or 'L' for list): pl
System hostname? (short form, e.g. 'foo') crimson_obsd
The hostname can be pretty much anything without spaces, mine is "crimson_obsd". It will be a part of the command prompt and can be used to address the system on a network.