The Zx Spectrum Ula- How To Design A Microcomputer -zx Design Retro Computer- May 2026

If you are building a ZX Design retro computer clone today (like the Harlequin or the ZX-UNO), you must replicate these ULA signals:

If you are restoring a ZX Design retro computer, put a finger on the ULA. If it is cold and the screen is white, the ULA is dead. If it is hot and the screen is flickering vertical lines, the lower RAM (attached to the ULA) is dead. If you are building a ZX Design retro