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

Unlike linear framebuffers (like the VIC-II in the C64), the Spectrum’s screen is a fractal nightmare. The memory map looks like this:

However, the ULA was a double-edged sword. It was . Once you printed the mask, you couldn't change it. The Spectrum’s infamous "attribute clash" (color fringing) wasn't a bug; it was a physical limitation of how many gates Altwasser could fit into the die to decode video memory. Unlike linear framebuffers (like the VIC-II in the

Because the ULA is too dumb to multiply. Unlike linear framebuffers (like the VIC-II in the

To save RAM (and gates on the ULA), the Spectrum famously splits color from pixels. Unlike linear framebuffers (like the VIC-II in the

Projects like the ZX Uno use FPGAs to mimic ULA logic perfectly.