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💾 A tiny and mighty boot sector OS

267 starsAssembly

OSle now has a C API and still fits in 510 bytes

by shikaan·Mar 7, 2026·2 points·0 comments
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AI Analysis

●●●●GemWizardryZero to One

Full C runtime in a 510-byte bootloader—genuinely impressive constraint engineering.

Strengths
  • •Maintained over 10 months with thoughtful evolution (assembly-only → C SDK without size bloat).
  • •Browser-based demo lowers barrier to experimentation; SDK with standard toolchain enables real userland programs.
  • •Pure constraint-craft: same impossible feat (OS in bootloader) now with broader accessibility via C.
Weaknesses
  • •Real-world utility is nil—hobbyist/educational interest only; no practical system use case.
  • •Limited by real-mode x86 and 510-byte footprint; any meaningful expansion breaks the premise.
Target Audience

Low-level systems programmers, OS dev hobbyists, constraint-based coding enthusiasts

Similar To

asm.js · TinyGo · Whitespace (esoteric language)

Post Description

About 10 months ago I posted OSle here [1], an OS in x86 assembly that fits in the 510 bytes of a bootloader. It got great discussion and I kept working on it. All userland programs were 16-bit assembly until last week. I started playing around with giving it a C runtime and here we are: you can now write programs for OSle in C. The SDK ships a small C runtime that provides the same API the assembly SDK has — file I/O, process management, screen output. Guest programs compile with a standard toolchain and run on the same 510-byte kernel.

Try it in the browser: https://shikaan.github.io/osle/ [1]: https://news.ycombinator.com/item?id=43866585

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