A Pico-Based ZX Spectrum Emulator

The ZX Spectrum was a popular computer of the 8-bit era. Now, it’s possible to emulate this machine on a microcontroller so cheap that it’s literally been given away on the front cover of magazines. Yes, we’re talking about the Pico ZX Spectrum project.

The project consists of all the necessary code to emulate a ZX Spectrum upon the hardware of the RP2040 microcontroller that makes up the Raspberry Pi Pico. The community has then taken this code and run with it, using it as the basis for all manner of different ZX Spectrum builds. If so desired, you can go barebones and use the Pico to run a ZX Spectrum off a breadboard with HDMI video output. Alternatively, you can build something like the PicoZX from [Bobricius]. The handheld computer features a PCB-based housing, along with an LCD and an integrated keyboard. Other configurations support features like USB keyboards, VGA outputs, and working sound output.

It’s great to see a classic 8-bit computer reimagined in all kinds of new tribute form factors. The Spectrum was always beloved for its neat all-in-one design, and there are several modern remixes that riff on that theme. The fact that they can all be powered by a cheap single-board microcontroller is all the more astounding. Video after the break.

18 thoughts on “A Pico-Based ZX Spectrum Emulator

  1. The project from the picture looks like it achieved something I tought was absolutely impossible:

    Building a computer with a worse keyboard than the original Spectrum.


    A ZX Spectrum was my first computer. I loved my speccy. I still have it. I typed in endless programms on that gummy atrocity of a keyboard it came with and I still feel the pain today.

    1. If you want a DIY keyboard, especially for small and low profile, the switches used here are the most common. Unfortunately, they are also crap. The small top is great for poking out of a (labelled) backplate, but lousy for actual typing.
      If manufacturers have a switch with the same PCB area, but a larger area button on top, it’s not easy to find. There are several projects besides this one, that would benefit from such a switch.

      1. It may not work for this specific board, where the switches need a long button to poke up through a layer of PCB, but it’s quite reasonable to 3D print wider keycaps for these little switches. With a well-calibrated printer you should be able to make them a press-fit with no post-print rework required.

    1. I think the same, but in a more sarcastic way. Graphics like ZX Spectrum and CGA deserve a monochrome screen. Both would looks most eyefriendly on a 1950s-1970s b/w TV set over RF cable. I really mean it.

      PS: I think the handheld was well done, all in all. I’m just not a ZX Spectrum fan due to the way graphics work,I guess. I’d rather use a ZX81 instead. The game collection of the ZX is very depressing, very British I think. Not my taste. On the bright side, the ZX Spectrum has a few nice amateur radio programs for RTTY and SSTV. So that would be an interesting aspect to tinker with.

      1. ‘The game collection of the ZX is very depressing, very British I think’
        I really don’t understand…one of the universally acclaimed strengths of the ZX Spectrum was the huge amount of game software it had from all manner of developers
        I mean people are still writing games for the Spectrum now, 40 years after its release

  2. It always surprises me the amount of negative comments aimed at Sinclair computers by people who never used them. I had a 16k, grey keyed Spectrum from new and enjoyed every single moment learning to program it. The keys had a good click, or beep depending on the value you used on “Poke 23609,xxx”. The shortcut commands quickly became instinctive and switching to a BBC was slow and tiresome to program in comparison. There were many shortcomings which are easy to criticise now, but there were many revolutionary things which inspired owners into a career in IT. If it was as bad as people would have you believe, why would people still talk about them now, and recreate modern versions.

    1. I only have one point of critique for that system, no real support for mass media, everything is build around the tape. A port of Maniac Mansion for example would be a true test of patience, not speaking of Ultima. I tried Gauntlet 2 and the constant loading from tape ruined an otherwise passable port.
      My father had one back when they where still fairly new, sold it a fortnight later and got himself a C64 with a 1541 and SpeedDOS. Not because of the hardwares capabilities but because of load times and, thanks to the medium of choice, very few RPGs. All the heavy hitters needed multiple disks on the C64 and would have been nigh impossible on the Spectrum.

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