Harlequin 128 PCB Board, Issue 4B, ZX Spectrum Clone

Harlequin 128 PCB Board, Issue 4B – ZX Spectrum Clone

Revive your memories of the classic ZX Spectrum computer with the Harlequin 128 PCB Board, Issue 4B – the perfect solution for retro electronics enthusiasts and DIY hobbyists. This high-quality ZX Spectrum clone is not only a tribute to the legendary hardware but also an excellent base for building your own 8-bit computer.

A Spectrum You Can Build Today

The biggest challenge in recreating the ZX Spectrum is the ULA chip — a component that is no longer manufactured and is prone to failure in original machines. Harlequin solves this differently: the entire ULA logic has been replicated using standard 74-series chips, based on the analysis described by Chris Smith in his book The ZX Spectrum ULA. As a result, every component of this computer can be purchased from a regular electronics store, and in case of failure, it can simply be replaced.

This is not emulation or FPGA-based construction. It’s the same digital circuitry as the original, built from separate gates. Video signal, timing, and the characteristic visual artifacts behave just like in a real Spectrum — including programs that can detect these features.

What the Finished Computer Can Do

• 128 KB RAM with full bank switching and ALL RAM mode
• DIP switch ROM selection — Flash memory 29F040 / 39SF040 holds up to 8 banks of 64 KB. In one machine, you can have 48K, 128K, +2, +2A/+3/+3E side by side and switch between them without soldering
• AY-3-8910 sound chip — three-channel 128K sound, plus the standard beeper
• Kempston joystick port
• RGB and composite output, support for PAL and NTSC (NTSC requires an additional 3.579 MHz oscillator)
• Switchable 48K / 128K timing — for programs sensitive to timing differences between models
• Powered by a standard Spectrum power supply: 9 V, center pin negative

Key Product Features:

• Precisely designed PCB: Issue 4B offers an optimized track layout, ensuring stability and reliability.
• Compatibility with ZX Spectrum 128: Perfect for retro enthusiasts who want to recreate the classic ZX Spectrum experience.
• Durable construction: High-quality materials ensure product longevity and durability.
• Solder mask: Black matte finish.

Who Is This Product For?

This project is for those who have soldered something more complex than a starter kit. The board includes over 40 integrated circuits in DIP packages and requires patient, careful assembly as well as basic diagnostic skills — a multimeter and oscilloscope will be very helpful if it doesn’t work on the first try. In return, you get a computer that you built yourself and can repair on your own.