Building a ZX Spectrum Clone in 2021 – Sourcing for parts

Acknowledgements – ZX sizif 512K Project – all credits to Eugene Lozovoy.

sizif 512K PCB from JLCPCB

The first order is to get the PCB made; the Gerber files are readily available on GitHub; make sure you choose the latest version (rev.D1). I used JLCPCB to manufacture the PCB as I am familiar with them. The boards came in under a week.

Sourcing for components isn’t that easy; with the rising cost of chips, an EPM1270 costs SGD$70, and the video encoder about SGD$25 on major online electronics distributors. To keep the cost low, almost everything I ordered was from China auction sites (Taobao); the problem with these sites is that there is a risk the chips are a dud, remarked or a total fake.

In total, based on the BOM, I ordered all the parts from 20 plus vendors; 3 or more pieces for ICs from different vendors if available.

A box full of components
No photo description available.
duds from China

  • CPU – Z84C0020PEC – these are all used at about $3 each, modern version for the Z80A, likely remarked from old Z80As. Out of 3 pieces, 1 is a dud; the other two work fine.
  • RAM – AS6C4008-55PCN – used static RAM for about $4 each, ordered 5, 2 not working.
  • ROM – SST39F040 – used Flash ROM for about $2 a piece, ordered 3 pieces all working.
  • Sound Chip – AY-3-8910 – These are hard to source in China, ordered three pieces, all dead. I still cannot find a good source for it.
  • Video Encoder – AD724 – These are still in production; I got them as new chips, no issues with them.
  • ULA – EMP1270 – These are new parts; most sellers won’t ship without you committing to a minimum order, I need some back and forth with sellers to get it.

Connectors and switches are a hit and miss; you buy them by looking at the picture of the item, which some might be misleading; most of them fit, but they gave me a short tactile switch instead of the long one.

The rest of the parts are ok, except the 28Mhz crystal; it is sold without specifications that cause issues during the build.

The keyboard connectors are from Digikey; it would be tough to get them from China. It might be cheaper to get it from the regular UK retro parts vendors.

link to part 1

link to part 3

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