The Spectrum’s quirks (like color clash) became its iconic aesthetic. 🚀 Resources for Builders
This is the ULA’s most famous "quirk." Since the ULA and CPU both need the memory to function, the ULA would "halt" the CPU clock whenever it needed to draw the screen, leading to what programmers call contended memory .
Chris Smith’s The ZX Spectrum ULA: How to Design a Microcomputer