To design your own retro computer, start with the video signal. The Spectrum’s ULA produced a signal.
By cloning the ULA, modern engineers prove that the original design principles—centralized logic, tight coupling of video and CPU, and aggressive cycle stealing—were not mistakes, but intentional choices. To design your own retro computer, start with
The Z80 runs at 3.5MHz. The ULA runs the main clock. The ULA generates two phases: Φ1 (CPU operates) and Φ2 (ULA operates). To design your own retro computer