Recreating the ZX Spectrum experience hinges on reproducing both function and timing. Using an FPGA to implement a modern ULA lets you preserve the machine’s behavioral quirks (what made the Spectrum special) while adding modern conveniences for portability. Start with a focused FPGA video/DRAM prototype, iterate with a simple ROM and Z80 core, and build outward—balancing authenticity and usability to produce a compact, lovable retro microcomputer.
If you want, I can: provide a sample FPGA ULA block diagram, draft a minimal memory map and port list, or outline a parts list with specific component models. Which would you prefer next?
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Do you need help writing the for the video timing matrix? Share public link
Use a Lithium-Polymer (LiPo) battery paired with a dedicated charge management IC. If you want, I can: provide a sample
The signature visual style of the ZX Spectrum—including its infamous "attribute clash"—is a direct consequence of the ULA's budget-conscious design. Screen Memory Layout
Whether building a desktop replica or a portable "Speccy," there are three main hardware paths: Discrete Logic (The "Harlequin" Method): Projects like the Harlequin board available on replace the unobtainable ULA with standard TTL logic chips This link or copies made by others cannot be deleted
: Ideal if you want to build a hardware replacement drop-in chip for an original board. Altera/ Intel Cyclone IV Go to product viewer dialog for this item. ICE40 FPGA Go to product viewer dialog for this item.
Because original ULAs are scarce, modern designs often use FPGAs (Field-Programmable Gate Arrays) to replicate the ULA's functionality, a process often documented on platforms like YouTube . Alternatively, you can use discrete 74-series logic chips, though this results in a much larger board. 3. Retro Computer Design: Building Your Own
Will you use a or microcontroller emulation ?
Here is a practical block diagram for a battery-powered Spectrum portable using the route (authentic CPU feel):