CSS Electronics' ZX Nucleon Is an Eight-Bit Clone-of-a-Clone Designed with Russian Software in Mind

Czechia-based vintage computing specialist CSS Electronics has launched a clone of the Pentagon microcomputer of the 1980s — itself a clone of the Sinclair ZX Spectrum — with the promise of full compatibility with "the best quality software" from the 1990s and early 2000s.

Released in 1989, the Pentagon — Пентагон — was a clone of Sinclair's popular ZX Spectrum designed by Vladimir Drozdov for the Russian market. Release of documentation for do-it-yourself creation led to its widespread adoption - though timing differences between the Pentagon and the original ZX Spectrum led to software compatibility issues.

That's where CSS Electronics' ZX Nucleon 512KB comes in: Based on the Pentagon, it offers timing compatibility for Russian software.

"The vast majority of the best quality software from the 199x-20xx period comes from the countries of the ex-USSR," the company claims. "This software largely uses Pentagon timing and does not work on ZX Spectrum and its derivatives. That's why ZX Nucleon is the best choice for the future."

"The motherboard is the same size as the ZX Spectrum 48K computer board and will fit into his case. Electrical wiring is largely based on Pentagon 128KB/512KB computer and keeps timing important parts of the computer!"

It's not a slavish clone, however. CSS Electronics has opted to use modern static RAM (SRAM) in place of the dynamic RAM (DRAM) of the original, while the design includes a range of minor bug fixes and an improved video output section — including the option for full RGB output. To round things out, the board includes a Microchip AY-3-8910A programmable sound generator chip.

The board is now available, fully assembled, on CSS Electronics' Tindie store at $159.