When you played the Nintendo Entertainment System, you were close to the hardware. It's why you can pull off remarkable glitch hacks, like playing Tennis to hot-boot into broken Super Mario Bros. worlds. The chips, the memory, the board—everything was designed to service the little board inside your cartridge (that and prevent unauthorized games). There wasn't much room for anything else in the early- to mid-1980s.

Room enough, however, for a custom-built operating system built in 2022, if just barely. NESOS 1.0 from Inkbox Software, a 48K OS, features "two core applications, the word processor, and the settings," according to Inkbox. The settings app gives you seven cursors, 53 background colors, and the ability to delete the eight files that can fit inside a maximum 2K of NVRAM (i.e., onboard memory that doesn't lose data when the system loses power). That's 832 bytes each, or about one full screen's worth of memory. You can drag those eight files anywhere you want on the desktop, however.

NESOS (pronounced "nee-sohs," according to its creator) is entirely graphical. Inbox notes that there's already a command-line system, Family Basic, for the NES and its Japanese progenitor, the Family Computer/Famicom. "I want NESOS to feel like an actual operating system that Nintendo might have made back in the day for the NES. What would it have looked and felt like?" the creator says in his video overview.

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Inkbox is no stranger to NES programming, nor quirky code projects that present as wonderful art. They previously built a fruit-based MMO in less than 40 hours (seemingly no longer active), a Super Mario ROM Hack that refashioned the game in the style of the Ming Dynasty tale Journey to the West, and a Chinese word processor for the Apple II, made natively on the Apple II.

The NES gave Inkbox two 256-slot grids of sprite memory to work with, one for foreground and one for background, though the system can only show 64 sprites at a time. You can combine the 8×8 sprites into larger shapes, however, for the OS and UI. As for input, a keyboard was bundled with some versions of Family Basic, the HVC-007. Inkbox imported the characters used in Super Mario Bros., gave the keyboard some additional shortcuts, and he had a tiny typing app going. If you're using a standard NES controller, you're holding A to cycle through characters, tapping B as your space bar, and holding Select with either of those keys to reverse them.

Inkbox's video goes on to explain how this all works in NES memory, involving manipulation of the Picture Processing Unit (PPU), giving his virtual NES cartridge the same kind of storage that battery-backed games had, and shuttling each file, byte by byte, between them.

You can download an emulator-friendly ROM of NESOS at Inkbox's site or at ROMHacking. A two-frame, eight-pixel hat-tip to Hackaday for pointing us toward this marvel.