The Zx Spectrum Ula How To Design A Microcomputer Zx Design Retro Computer Portable -

By merging Chris Smith’s foundational research on the original ULA mechanics with today’s highly integrated FPGA logic and lithium battery technology, you can successfully design and manufacture a custom, cycle-accurate, and fully portable retro microcomputer.

The most critical function of the ULA was generating a television signal (PAL or NTSC) while reading pixel data from the RAM. The ZX Spectrum used a unique, cost-saving memory layout:

Use a TP4056 or IP5306 charging IC to safely handle USB-C charging, over-discharge protection, and battery status LEDs. By merging Chris Smith’s foundational research on the

It is possible to rebuild the ULA using 74-series logic chips (counters, multiplexers, shift registers). However, the chip count exceeds 40+ ICs, making portability impossible. This approach is recommended only for desktop replicas.

Forget the original ULA. You need an (Field Programmable Gate Array). The cheapest and most documented for this task is the ICE40UP5K or the Xilinx XC9572XL for a CPLD, but for a full ULA+Z80, use an EP4CE10 (Cyclone IV) or an Lattice iCE40 HX8K . It is possible to rebuild the ULA using

The ZX Spectrum's portability and compact design were key factors in its popularity. When designing a retro-style microcomputer, consider the following:

Before soldering, we must redefine the goal. A "portable" retro computer is not just a Spectrum in a lunchbox. It must adhere to three constraints: Forget the original ULA

Do you prefer an or a microcontroller-based emulation approach ?

Will you be designing a custom , or working with development boards ? Share public link

The ULA reads a 6.14K pixel map and a 768-byte attribute map from the lower 16KB of RAM.

No portable is complete without a case. Use or Fusion 360 .