November 16, 2025
Press F for Real Mode drama
Writing a DOS Clone in 2019
Retro OS comeback: fans crave details, nostalgics say it looks easy
TLDR: An engineer built a 1980s-style DOS clone that runs basic programs. Commenters split between calls for deeper technical detail and claims DOS clones are easier than modern systems, turning it into a nostalgia-fueled DIY debate that matters because it demystifies how computers really work.
An engineer used his sabbatical to resurrect the 80s by building a DOS-compatible operating system, and the comments turned into a retro reunion with a side of drama. One camp came in hot: “too short for the given topic” demanded deep dives, diagrams, and gritty code — the nerds want the receipts. The other camp waved nostalgia flags, insisting that with so many DOS clones back in the day, this might be “comparatively easy” and, honestly, kind of fun to try.
For the rest of us, here’s the simple version: DOS was Microsoft’s old text-only system where programs could poke anywhere in memory — a wild west called “Real Mode.” Andrew’s build includes a command prompt, basic disk and clock drivers, a tiny file system (FAT-12), and enough features to run some classic apps. Future dreams: better directories, piping, multiple drives, and fancier file systems.
Cue the memes: floppy-disk GIFs, “C:>” one-liners, and shout-outs to Caldera OpenDOS and Concurrent DOS. The spicy debate: is writing a clone now a weekend flex or a hidden boss fight? Nostalgia says “let’s do it,” detail-chasers say “show your work.” Either way, the retro bug is contagious — and comments want more.
Key Points
- •The project is a DOS-compatible operating system built during a one-month sabbatical, inspired by retro-computing and prior emulator work.
- •It implements about half of the extended DOS API, with drivers for disk, console, and system clock, a FAT-12 filesystem, and a COMMAND.COM shell.
- •The OS runs in x86 Real Mode for full MS-DOS compatibility, avoiding modern features like Protected Mode, paging, GDT, and rings.
- •Current functionality includes running internal commands, directory listing, and executing COM programs; it can run some DOS software.
- •Planned enhancements include better directory support, multiple drive handling, piping/redirection, FAT-16 and other filesystems, and a text editor.