Tagged: Deep dive

The port that lies about its own number

Every Spectrum program you've ever typed says OUT 254 or IN 254. The ULA doesn't actually check for 254 — it barely checks anything at all. A tiny program proves it, live, on screen.

The picture that is also a program

A single SCREEN$ file that displays a picture when loaded to the screen — and runs as Z80 machine code when loaded anywhere else. The code is literally visible as colours.