[PumpkinSpice]

Folks here are probably reading too much into the "boot sector" angle. This project, like many others on HN, is best understood as "doing something in a constrained way because it's a fun challenge." As to why 512 bytes, the honest answer is "because it's a round number with some vague retro connotations."

There was never a constraint on x86 that you had to fit any real functionality into a single disk sector. All the bootsector code ever did was setting up the registers and calling BIOS to load more data from disk - and the only reason you had this done in stages was so that BIOS wouldn't have to know the particulars of your OS, such as where to find the kernel or what address to put it at.

For what it's worth, the pre-boot BIOS environment was always quite featured, offering text and VGA graphics, disk and keyboard handling, and so forth. In fact, when you look at something like MS-DOS, it was actually the BIOS-side code that was doing a lot of the heavy lifting. MS-DOS was halfway between a shell and a "real" OS as it is understood today.

Nowadays, with UEFI, we essentially decided to make the initial code executed by the CPU an operating system in itself, with filesystem support and so forth - and the notion of a 512 byte first-stage bootloader is largely gone.

[xorvoid]

Somebody with a fine taste in fall beverages gets it! Lol

[userbinator]

UEFI is almost like protected-mode DOS, with its support for things like filesystems and networking.