X-87 paints a DOS landscape with 256 bytes and a very patient CPU
A browser sketch became a tiny x87 experiment, with emulator compatibility proving harder than the first pretty picture.
The landscape needs time to develop. Literally. X-87 keeps adding points until a barren scene and an accidental moon emerge, which gives a DOS program a rather good excuse for looking busy.
The maker’s write-up describes a 640-by-400 image in 32-bit color, generated by x86 and x87 instructions. The executable occupies 256 bytes. Its scenery comes from equations and repeated plotting, so there is no photograph tucked inside waiting to be unpacked.
A raw frame at that resolution and color depth occupies 1,024,000 bytes: 640 times 400 times four. That’s 4,000 times the program’s size, calculated before considering any image-file header. The program still needs working memory and a graphics environment; a small recipe doesn’t shrink the kitchen.
The project began with browser sketches, moved through a Forth version, and reached DOS through several rounds of shrinking. That path matters because the finished file conceals the experiment that produced it. The tiny result can make the work appear effortless, rather like seeing a clean desk immediately after someone crammed everything into a drawer.
At default DOSBox cycles, the author reports approximately 13 minutes. At maximum cycles on the same host, roughly two minutes and ten seconds. That spread gives anyone trying it a practical first check: a slow reveal may be exactly what the chosen emulator speed produces. Patience has a configuration file.
The byte savings also have consequences beyond speed. X-87 reuses data, compresses constants and combines loop bookkeeping. A constant that can do two jobs saves space, but changing it can then disturb two jobs. Anyone accustomed to editing a parameter in a roomy application should expect a much tighter squeeze here.
Compatibility demanded another pass after the picture looked finished. The write-up distinguishes a version checked in Bochs with FreeDOS from untested real hardware. Looking right under one emulator had left artifacts and initialization problems elsewhere. That is an unusually concrete answer to the familiar claim that something works on the developer’s machine (congratulations to that machine).
The source offers more than a screenshot to admire. Comparing the browser, Forth and DOS implementations makes the tradeoffs visible: the same visual idea can become several very different programs once the available bytes change. That gives a reader something useful to inspect even without becoming an x87 enthusiast over lunch.
A future version might reduce the color depth or choose different constants. The author leaves that possibility open. The unresolved part is how much of the mood survives the next reduction, especially when the moon already arrived by accident.
The moon gets to stay.