Implement the Logic (The ULA Replacement)For an authentic hardware feel, use a CPLD (Complex Programmable Logic Device) or FPGA. These chips can be programmed to behave exactly like the Ferranti ULA. If you prefer a software-defined approach, a high-speed microcontroller can "bit-bang" the video signal and manage memory timings.
Think of a ULA as a "semi-custom" chip. It came from the factory with a grid of logic gates (NAND and NOR gates) already printed, but unconnected. An engineer would then design the connections between these gates to create specific functions. Implement the Logic (The ULA Replacement)For an authentic
: Delaying the CPU's access to the lower 16KB of RAM when the ULA needs it for the display, leading to "contended memory" behavior. Think of a ULA as a "semi-custom" chip
The ULA was a tightly coupled video+memory controller . You cannot make a simple ZX clone without replicating this arbitration. : Delaying the CPU's access to the lower
: Uses readily available parts and avoids "ULA bugs" like the "snow effect". 2. FPGA-Based Design
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