The Zx Spectrum Ula- How To Design A Microcomputer: -zx Design Retro Computer- Extra Quality

entity zx_ula is Port ( clk : in STD_LOGIC; cpu_addr : in STD_LOGIC_VECTOR(15 downto 0); cpu_data_in : in STD_LOGIC_VECTOR(7 downto 0); cpu_data_out : out STD_LOGIC_VECTOR(7 downto 0); video_rgb : out STD_LOGIC_VECTOR(2 downto 0); hsync, vsync : out STD_LOGIC; ram_we : out STD_LOGIC; ram_addr : out STD_LOGIC_VECTOR(14 downto 0); ram_data : inout STD_LOGIC_VECTOR(7 downto 0)); end zx_ula;

You want to design a microcomputer. You cannot buy a Ferranti ULA today. But you can use an (Field Programmable Gate Array) to emulate one. Here is the minimal VHDL code to replicate the Spectrum's memory contention. entity zx_ula is Port ( clk : in