Using a disk image is very easy: download the file, mount it through a so-called “loopback” device and your OS will see the image as it was an real harddisk, CDR or DVD. When I needed to test the IDE-drivers, the partitioning-functionality, the ext2 drivers etc, I wanted to use just such an image so I can quickly make modifications and check how the actual structure looked like, just by reading the disk image file. This is a great help when it comes to debugging.
Welcome to the first part of CybOS. We talk a bit about the bootsector. From part 2 on, everything is “kernel based”, which means we have setup the system and jumped to our main kernel. From there, things get really interesting so I jump a bit fast to the boot code. However, in the end of this post, the source code for the bootsector (and second stage loader) can be found so you can see what’s going on.
Somewhere in 1998 or even earlier, I started my own little project in creating a - functional - Operating System from scratch. Not a linux clone and not a MS-DOS wannabe. Just a simple OS that is functional in such that some tools, games etc could actually work, not caring about Posix compliance, fancy graphics or all hardware support you can think of..
So, today, 12 years later, where are we?