The Zx Spectrum Ula How To Design A Microcomputer Zx Design Retro Computer Portable New! File

It handled the "contended memory" system, where the CPU and video hardware shared RAM.

always @(posedge clk_14m) begin if (hcount < 128) begin // 64 us fetch period mem_oe = 1; // ULA reads screen cpu_wait = 1; // Stall Z80 end else begin mem_oe = 0; cpu_wait = 0; end end It handled the "contended memory" system, where the