First, build the kernel and filesystem (just make). In short, you need to
build this on an x86 Linux machine. If you wish to try to compile on an OS
other than Linux you may need modify the Makefile to compile sh
using a cross-compiler that produces ELF binaries - i.e. a cross-compiler
targeting x86 Linux. In short, you need to build this on an x86 Linux machine.
Next, find a suitable machine to run the OS on. It should be perfectly safe, and since it does not directly attempt to access any hard disk drives (only a RAM disk loaded by the bootloader) it should do no damage to your existing setup, BUT I ACCEPT NO LIABILITY FOR ANY DAMAGE DONE BY THIS PROGRAM. Run it at your own risk. The OS has been tested on half a dozen machines or so, and worked on all but one. The failure came in the form of the machine rebooting itself midway through loading the OS, with no nasty side-effects.
Hardware requirements - i386 or better processor, but the GUI is surprisingly power-hungry, so I would recommend a fast P3 or P4 processor (has been tested on P3/P4/Athlon machines). Minimum RAM is something like 32MB. PS/2 mouse & keyboard required - no USB I’m afraid, and the keyboard map is for a UK keyboard. Uses VESA VBE 3.0, so should work on any modern graphics card (has been tested on NVIDIA, Matrox, and SiS cards).
Now you need to setup a bootloader to load the OS. If you have a system
using a lilo bootloader you can simply add the OS to your boot menu. Just add
appropriate image= and initrd= lines to your /etc/lilo.conf, pointing at
kernel and fs.tar respectively (as built by make earlier), then run lilo.
If you do not wish modify your lilo setup, one easy option is to get yourself a
GRUB boot disk image, and follow the instructions for GRUB below - Debian users
can simply runapt-get install grub-disk to get themselves a GRUB boot disk.
If you run GRUB, then at the boot menu simply hit c to get a console, then
type kernel=(hd0,0)/<PATH>/kernel (substituting appropriate hard
drive/partition numbers & path, or using (fd0) to load a kernel on the
floppy), then initrd=(hd0,0)/<PATH>/fs.tar, and finally boot.
Assuming the OS has booted, what can you do now? Well, start by trying sh,
to open another shell. Then, try vi gavin.c to open up the OS source in a
text file viewer (up/down or PgUp/PgDn to scroll). Note that the provided
applications, sh and vi both have windows of the same size, and both open in
the top left corner of the screen, so you may need drag the windows around a bit
to tell them apart.
To shut down - just hit the power button. :-)