The Zx Spectrum Ula- How To Design A Microcomputer -zx Design Retro Computer- ((top))

A is a semi-custom IC. It consists of a standard grid of transistors ("uncommitted") that are connected together in the final manufacturing step using a custom metal layer.

, based on the definitive research by Chris Smith in his landmark book, The ZX Spectrum ULA: How to Design a Microcomputer What is a ULA? A is a semi-custom IC

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