Both the CPU and ULA need the RAM. The ULA wins, "pausing" the CPU to draw the screen.
Designing a microcomputer—whether a 1980s retro classic or a modern FPGA-based recreation—revolves around the delicate dance between the CPU and its supporting logic. This article explores how the ZX Spectrum ULA redefined hardware design and what it takes to recreate that magic today. 1. The Heart of the Machine: What is a ULA? Both the CPU and ULA need the RAM