The Zx Spectrum Ula- How To Design A Microcomputer -zx Design Retro Computer- !exclusive! (TOP-RATED)

• Controlling the ZX Spectrum's 16 KB or 48 KB of RAM
• Generating the video signal for the TV output
• Handling keyboard and joystick inputs
• Managing the cassette interface
• Providing interrupt handling and timing

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; Microcontroller-assisted hybrid

Ferranti produced the ULA using a "diffusion programming" technique. Unlike a mask ROM or a gate array, the ULA started as a standard base wafer of unconnected gates. The final metal layer was customized via a computer-controlled electron beam. Controlling the ZX Spectrum's 16 KB or 48

What is a ULA?

To design a microcomputer like the ZX Spectrum, you'll need to consider the following key aspects: cpu_addr : in STD_LOGIC_VECTOR(15 downto 0)

Repairability Nightmare:

If the ULA died, the computer was e-waste. This was the antithesis of the Apple II (which had socketed TTL chips). This trade-off (unrepairable vs. affordable) defined the British home computer boom.