If you own a Sinclair ZX Spectrum—whether it’s a pristine 48K rubber-key, a battle-hardened 128K Toastrack, or a modern clone like the Harlequin—you know one universal truth: these machines are nearly 40 years old. Capacitors leak. RAM chips fail. The ULA (Uncommitted Logic Array) gets finicky.

By running this test program, you'll be able to verify that your ZX Spectrum is functioning correctly and identify any potential issues.

Example test routines (described, not code):

You're referring to the ZX Spectrum, a classic British home computer from the 1980s!