Steve Anderson's Loki Is a "Super Spectrum" Combining Raspberry Pi 4 and FPGA Power in a Custom Case

Hardware hacker Steve Anderson's Loki is a near-cyberdeck with a difference: alongside the almost-prerequisite Raspberry Pi single-board computer is a field-programmable gate array (FPGA) board designed to provide compatibility with the vintage Sinclair ZX Spectrum home computer family.

"Like roughly 102% of cyberdeck builds there's a Raspberry Pi inside," Anderson writes of the work-in-progress Loki. "Unlike those builds Loki also has hardware-level ZX Spectrum compatibility thanks to a ZX Uno FPGA board lurking in there as well. Both can operate at the same time, with the 2K display and hand-wired keyboard switching between the HDMI and USB of the Pi, and the VGA and PS/2 of the ZX Uno."

That's not the only hardware housed inside Loki's luggable casing: there's a Raspberry Pi Pico, which uses its RP2040 microcontroller to interface with a mechanical keyboard, providing the unusual ability to switch between connecting to the Raspberry Pi 4 Model B over USB and the ZX Uno via PS/2 and offering a compact OLED panel for status display.

"Loki is sort of a cyberdeck," Anderson writes, "although I don't like to call it that because it's not set out to be hyper-portable. It does however have a battery pack, as well as taking a 12V PSU input. Loki's display is a 2K screen from an iPad. The driver board has both HDMI and VGA inputs, so they can be switched from one to the other. The HDMI input passes through a KVM switch so that external boards can use the keyboard, trackpad and screen as well."

While the name may conjure up images of the Norse trickster god, or Marvel's popular interpretation of the same, that isn't the source of the moniker: "Loki isn't named after the Marvel anti-hero (although I loved the show), nor (directly) to the Norse god, but after a mocked-up 'Super Spectrum' that Sinclair User magazine made a big deal about, and that young me wanted desperately to own, but didn't actually exist," Anderson explains. "Given that was a dream computer to me then, and this is whatever I want it to be, this is my Loki."

Full progress reports for the work-in-progress build are available on Anderson's website, where the project has been documented since November last year; additional information is available on the Loki Hackaday.io page.