The Zx Spectrum Ula- How To Design A Microcomputer -zx Design Retro Computer- [upd] -

Chips like the Xilinx CoolRunner or Altera Cyclone are programmed via hardware description languages (VHDL/Verilog) to mimic the exact clock-cycle timing, video delays, and contention quirks of the original Ferranti chip.

In the early 1980s, building a microcomputer required dozens of separate integrated circuits (ICs). You needed a Central Processing Unit (CPU) to handle logic, separate chips to manage video output, chips to handle keyboard input, and more chips to interface with system memory. Every extra chip added to a motherboard increased: More parts to buy and solder. Physical size: Larger circuit boards were required. Chips like the Xilinx CoolRunner or Altera Cyclone

Designing a retro microcomputer like the ZX Spectrum requires balancing cost against computational performance. A typical 8-bit architecture splits tasks among distinct components that must communicate over shared buses: Every extra chip added to a motherboard increased:

Designing a microcomputer around a ULA required overcoming specific hurdles: A typical 8-bit architecture splits tasks among distinct

Appendix A: Timing Diagram of ULA Contention Appendix B: Die Shot Annotation (4-bit counter and pixel shift register) Appendix C: Modern Verilog implementation of the attribute clash logic