2026 Retrocomputing Challenge: Custom RISC-V Processor For Retro System

October 28, 2026 by Bryan Cockfield No comments

Although once little more than an academic endeavor, the RISC-V architecture is slowly supplanting applications that would have normally gone to ARM. Even a few microcontrollers have chips running this open-source instruction set now, and we expect it to grow in the future since it doesn’t require the licensing of an ARM or x86 chip. [M_Jagadeesh97] is getting ahead of the curve with this retro gaming system built on a custom-designed RISC-V system.

Most of us, presumably including [M_Jagadeesh97], don’t have access to chip fabrication tools, but what we can get is any of various FPGAs. This RISC-V CPU is built on a Terasic DE0-Nano board with 32 MB of RAM available to it, and boots to a launcher with 32 games available. There are a few limitations with this low-power system which was largely solved by limiting the display to 64×32, which lets it maintain the same aspect ratio as the original DOOM as well as the same aspect ratio for many of the older games, while still maintaining 45 FPS.

The project writeup goes deep into the design of a system like this, from the bare metal, the CPU design, the timing of the video signals, and how to implement a Wolfenstein-like raycaster. After adding a small display it looks to be fairly portable as well and is an excellent demonstration of how powerful inexpensive boards like this FPGA can be with the proper amount of effort.

Battery Prototype Uses Superextensive Quantum Effects To Charge Faster

October 28, 2026 by Maya Posch 2 Comments

Although the term ‘quantum battery’ is a bit of a vague term, the cell that [Kieran Hymas] et al. demonstrate in a recent paper does seem to suggest that it uses quantum effects to charge faster than would otherwise be possible, with this rate increasing faster than its volume, meaning at a superextensive rate.

The general idea behind a quantum battery is that these somehow use a quantum effect to store and release energy faster than would be possible using classical physics. First proposed in 2013, the initial Dicke model saw its theoretical quantum advantage shot down by 2020, leading to the search for alternative models.

We have previously seen claims of a quantum advantage in batteries based on the Sachdev-Ye-Kitaev model, such as by [Davide Rossini] et al., but this new paper may be the first prototype cell demonstrating a reproducible effect.

In the here demonstrated cell a microcavity is created with strong light-matter coupling, allowing for both energy storage and discharging, with the illuminated particles super-absorbing the light with what the researchers claim to be due to these particles cooperating using a quantum mechanism. Effectively scaling up the cell would thus scale up the charge- and discharge rate faster than in a conventional chemical cell.

Whether this demonstration can be replicated and expanded upon remains to be seen, naturally. The stored energy in this experiment was very small and the storage time only very brief, so for now it serves primarily as an interesting experimental result for researchers to dig through.

Hacking The Modern Tamagotchi With UART

October 28, 2026 by Bryan Cockfield 1 Comment

Although not technically the first virtual pet, the Tamagotchi handhelds certainly popularized the idea and made it a worldwide phenomenon. In the late 90s it was hard to go out in public and not see them dangling from backpacks and belt loops. They turned out to be more than a passing fad, too. There have been Tamagotchis in various forms since then, and one of the latest, the Tamagotchi Paradise, is uniquely hackable thanks to this custom UART interface.

The build starts with a simple and inexpensive CH340G UART adapter with a built-in USB interface. A custom 3D printed enclosure is used to house the adapter and also help to expose the interface to the Tamagotchi. This is done by wiring three pins to nickel strips, which are threaded through slits in the case and looped back around to create a pogo-style adapter for the Tamagotchi’s custom dock. Normally this would be used to link to other Tamagotchis, but in this case the USB-to-UART adapter mimics it, allowing for all kinds of in-game shenanigans. The project’s creator [Squalius] shows it off by connecting it directly to a browser tool in Google Chrome.

Not only that, but this can also be used to modify the software running on the handheld entirely, with the video showing demos playing not only Super Mario but also DOOM (of course). This isn’t too surprising given that these games are built with modern 32-bit ARM microcontrollers. For the 90s purists, though, it probably won’t surprise anyone to know that these devices have been the subject of various hacks almost since they came out.

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Does Running An E-Paper Display At 30 FPS Destroy It?

October 28, 2026 by Maya Posch 11 Comments

Although e-paper displays are famous for being low-power and lasting essentially forever if not damaged physically, the recent push to drive even cheaper e-paper displays at a framerate like 30 FPS for a decent monochrome gaming experience does raise a few questions. The first being what this does to the power usage of these displays, and the second whether this will wear out the display in short order. To investigate this, [Bo Made It] set up a few experiments.

Subject of this test was a Waveshare ESP32-S3-ePaper board, which had previously been demonstrated running a Game Boy emulator at 30 FPS. With this software running, the board consumed on average about 115 mA, which would run down the device’s 400 mAh battery in about 3.5 hours. From here key was to isolate the power consumption of the display itself, with the system minus the display updates consuming about 90 mA.

Running the frame calculations for the greyscale mode without rendering to the screen pushed that up to 107.6 mA, with even in the 30 FPS greyscale mode the display thus only consuming about 7.4 mA, which is vanishingly small. Clearly the low-power claims of e-paper remain intact even at higher framerates.

As for lifespan, one datasheet gives the typical lifespan as one million updates. This would translate to about 9.3 hours at 30 FPS, though that assumes a full display refresh. Since a smart driver only updates changed pixels, obviously this will be longer, but the question is how much longer, and what will degradation look like?

After running 2.16 million frames of a custom endurance test featuring repeating patterns, some ghosting was apparent, but repeated refreshing made this go away again. This means that so far no permanent damage has been detected within the no doubt conservative limit provided by e-paper manufacturers.

It should be noted that Waveshare itself also recommends against running such high-FPS applications on their device, meaning that this is definitely one big longevity experiment. If actual damage occurs, this means that obviously this won’t be covered under any warranty.

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C64 Keycaps For Everybody

October 28, 2026 by Zoe Skyforest 5 Comments

If you’ve got an MX-style keyboard and want some retro charm, you might like a recent project from [Levente Szabadkai]. It’s a set of C64-style keycaps that you can print yourself at home!

The project started as an attempt to produce a set of C64 keycaps for an Ajazz 75% keyboard layout, but [Levente] kept pushing until it developed into a universal set. The keys have C64 legends, plain legends, or blank, and work for ANSI boards from 60% to full size. There are a few ways they can be printed. — you can do two-color printing with an FDM machine, or you can print the caps alone and fill the legends with paint, either in FDM or resin.

As a part of this work, [Levente] had to obviously create the glyphs to print upon all the keycaps. He thus decided to release that as the C64 keyboard font, in fact. It’s available in TTF and OTF formats, and you can preview the font in your browser, if so desired. It includes the function key labels, the 63 PETSCII graphic font legends, and various symbols, punctuation, and selected accented letters, too.

We’ve seen lots of vintage C64 parts recreated from scratch. It’s been at the point for a while where you can build a new machine with what’s available off the shelf. They said Amiga would never die, but it’s the earlier Commodore that really lives on today…

Turning An Old Phone’s Motherboard Into An RC Plane Controller

October 28, 2026 by Maya Posch 9 Comments

Upcycling smartphones makes a lot of sense, especially since they contain so many components that remain useful long after their desirability as a smartphone has faded. In the case of [Mountain DS Lab], they opted to use an 8-year old Xiaomi Mi 8 phone to add long-range FPV video link and remote control functionality to an RC plane, using the phone’s LTE cellular connectivity.

The smartphone was bought used for $23, with the default Xiaomi ROM overwritten by LineageOS to get a more lightweight and up to date Android installation on it. From the video it’s clear that this phone has seen better days, with the glass back cracked and a few ugly lines running across the display. Fortunately all that is needed is the motherboard itself.

One gotcha here is that the OS checks for the display on boot and will time-out if it’s not present, potentially halting the process entirely. The workaround requires disabling the display in the device tree, which is done by modifying the boot.img file as explained in the video. Next a custom bracket for the motherboard was printed so that it could be fitted inside the target airplane.

To communicate with the avionics, a USB-to-UART adapter PCB was created with a CH340 IC on it. This was then connected together for an initial test, with the extended front camera being used as the FPV camera for the custom Android application. Using the controller via the remote LTE link worked with the flight controller, so next the airplane was assembled for initial testing.

From this point it’s all pretty standard RC airplane assembly and testing, just with the typical RF-based control and FPV link replaced with the LTE link. Unfortunately flying drones isn’t permitted in the immediate area where the creator lives, so only some taxiing was tried prior to its maiden flight at a local airstrip that will be featured in an upcoming video.

Naturally, this isn’t the first time that someone has tried this type of remote control, with the ongoing Russo-Ukraine war being a prime example of LTE-based remote control of drones. Although we do not advocate wiping out a third of a nation’s strategic bomber fleet with upcycled smartphones, ultimately this is the same technology and a good way to create an RC drone that can last more than the few kilometers eked out from a 2.4 GHz link or so. Just be prepared for the LTE link to add a few milliseconds of latency.

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JPEG-XL Is Back On The Menu

October 28, 2026 by Zoe Skyforest 22 Comments

Many of the image formats we’re familiar with have been around for decades. We all know JPEG and PNG like the back of our hands, and GIF even had a bit of a resurgence when tiny annoying looping animations became cool again on social media. There has been a growth in newer formats, though, like WEBP, and AVIF, with various platforms and software companies adopting them for greater efficiency, performance, and image quality.

Amongst the new crop of formats vying for relevance is JPEG XL. It was touted as a format that improved on what JPEG could do in the lossy compression space, while also adding on a lossless mode. There were grand hopes that it would become a universal replacement for all existing raster formats on the Web. A major problem was that Google was seemingly against it, only to backflip—with the format now slated to hit the big time with renewed backing from the search giant. So what’s going on?

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