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

The Ghost in the Gate Array

When you design your next microcomputer—whether in an FPGA, on a breadboard with 74HC logic, or in software emulation—remember the ULA’s three commandments: The Ghost in the Gate Array When you

The most brilliant aspect of the is how the ULA handled memory access. The Z80 CPU (the brain of the Spectrum) needs to access memory to run programs. Simultaneously, the ULA needs to access memory to read the screen data and generate the video signal. on a breadboard with 74HC logic

Use the following logical blocks when planning a single custom chip to replace discrete logic: the ULA consolidated the following functions

I/O Controller

In a single chip, the ULA consolidated the following functions, which would have otherwise required roughly 20 to 30 individual chips: