Author: Bryan Cockfield

1643 Articles

Crossing Commodore Signal Cables On Purpose

April 29, 2025 by 19 Comments

On a Commodore 64, the computer is normally connected to a monitor with one composite video cable and to an audio device with a second, identical (although uniquely colored) cable. The signals passed through these cables are analog, each generated by a dedicated chip on the computer. Many C64 users may have accidentally swapped these cables when first setting up their machines, but [Matthias] wondered if this could be done purposefully — generating video with the audio hardware and vice versa.

Getting an audio signal from the video hardware on the Commodore is simple enough. The chips here operate at well over the needed frequency for even the best audio equipment, so it’s a relatively straightforward matter of generating an appropriate output wave. The audio hardware, on the other hand, is much less performative by comparison. The only component here capable of generating a fast enough signal to be understood by display hardware of the time is actually the volume register, although due to a filter on the chip the output is always going to be a bit blurred. But this setup is good enough to generate large text and some other features as well.

There are a few other constraints here as well, namely that loading the demos that [Matthias] has written takes so long that the audio can’t be paused while this happens and has to be bit-banged the entire time. It’s an in-depth project that shows mastery of the retro hardware, and for some other C64 demos take a look at this one which is written in just 256 bytes.

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Kaleidoscopico Shows Off Pi Pico’s Capabilities

April 27, 2025 by 14 Comments

In the early days of computing, and well into the era where home computers were common but not particularly powerful, programming these machines was a delicate balance of managing hardware with getting the most out of the software. Memory had to be monitored closely, clock cycles taken into account, and even video outputs had to be careful not to overwhelm the processor. This can seem foreign in the modern world where double-digit gigabytes of memory is not only common, it’s expected, but if you want to hone your programming skills there’s no better way to do it than with the limitations imposed by something like a retro computer or a Raspberry Pi Pico.

This project is called Kaleidoscopio, built by [Linus Åkesson] aka [lft] and goes deep into the hardware of the Pi Pico in order to squeeze as much out of the small, inexpensive platform as possible. The demo is written with 17,000 lines of assembly using the RISC-V instruction set. The microcontroller has two cores on it, with one core acting as the computer’s chipset and the other acts as the CPU, rendering the effects. The platform has no dedicated audio or video components, so everything here is done in software using this setup to act as a PC from the 80s might. In this case, [lft] is taking inspiration from the Amiga platform, his favorite of that era.

The only hardware involved in this project apart from the Pi Pico itself are a few resistors, an audio jack, and a VGA port, further demonstrating that the software is the workhorse in this build. It’s impressive not only for wringing out as much as possible from the platform but for using the arguably weaker RISC-V cores instead of the ARM cores, as the Pi Pico includes both. [lft] goes into every detail on the project’s page as well, for those who are still captivated by the era of computer programming where every bit mattered. For more computing demos like this, take a look at this one which is based on [lft]’s retrocomputer of choice, the Amiga.

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Design Constraints Bring Lockbox To Life

April 27, 2025 by 1 Comment

One of the most paradoxical aspects of creating art is the fact that constraints, whether arbitrary or real, and whether in space, time, materials, or rules, often cause creativity to flourish rather than to wither. Picasso’s blue period, Gadsby by Ernest Vincent Wright, Tetris, and even the Volkswagen Beetle are all famous examples of constraint-driven artistic brilliance. Similarly, in the world of electronics we can always reach for a microcontroller but this project from [Peter] has the constraint of only using passive components, and it is all the better for it.

The project is a lockbox, a small container that reveals a small keypad and the associated locking circuitry when opened. When the correct combination of push buttons is pressed, the box unlocks the hidden drawer. This works by setting a series of hidden switches in a certain way to program the combination. These switches are connected through various diodes to a series of relays, so that each correct press of a button activates the next relay. When the final correct button is pushed, power is applied to a solenoid which unlocks the drawer. An incorrect button push will disable a relay providing power to the rest of the relays, resetting the system back to the start.

The project uses a lot of clever tricks to do all of this without using a single microcontroller, including using capacitors that carefully provide timing to the relays to make them behave properly rather than all energizing at the same time. The woodworking is also notable as well, with the circuit components highlighted when the lid is opened (but importantly, hiding the combination switches). Using relays for logic is not a novel concept, though; they can be used for all kinds of complex tasks including replacing transistors in single-board computers.

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Digital Squid’s Behavior Shaped By Neural Network

April 26, 2025 by 2 Comments

In the 90s, a video game craze took over the youth of the world — but unlike today’s games that rely on powerful PCs or consoles, these were simple, standalone devices with monochrome screens, each home to a digital pet. Often clipped to a keychain, they could travel everywhere with their owner, which was ideal from the pet’s perspective since, like real animals, they needed attention around the clock. [ViciousSquid] is updating this 90s idea for the 20s with a digital pet squid that uses a neural network to shape its behavior.

The neural network that controls the squid’s behavior takes a large number of variables into account, including whether or not it’s hungry or sleepy, or if it sees food. The neural network adapts as different conditions are encountered, allowing the squid to make decisions and strengthen its algorithms. [ViciousSquid] is using a Hebbian learning algorithm which strengthens connections between neurons which activate often together. Additionally, the squid’s can form both short- and long-term memories, and the neural network can even form new neurons on its own as needed.

[ViciousSquid] is still working on this project, and hopes to eventually implement a management system in the future, allowing the various behavior variables to be tracked over time and overall allow it to act in a way more familiar to the 90s digital pets it’s modeled after. It’s an interesting and fun take on those games, though, and much of the code is available on GitHub for others to experiment with as well. For those looking for the original 90s games, head over to this project where an emulator for Tamagotchis was created using modern microcontroller platforms.

Hash Functions With The Golden Ratio

April 25, 2025 by 9 Comments

In the realm of computer science, it’s hard to go too far without encountering hashing or hash functions. The concept appears throughout security, from encryption to password storage to crypto, and more generally whenever large or complex data must be efficiently mapped to a smaller, fixed-size set. Hashing makes the process of looking for data much faster for a computer than performing a search and can be incredibly powerful when mastered. [Malte] did some investigation into hash functions and seems to have found a method called Fibonacci hashing that not only seems to have been largely forgotten but which speeds up this lookup process even further.

In a typical hashing operation, the data is transformed in some way, with part of this new value used to store it in a specific location. That second step is often done with an integer modulo function. But the problem with any hashing operation is that two different pieces of data end up with the same value after the modulo operation is performed, resulting in these two different pieces of data being placed at the same point. The Fibonacci hash, on the other hand, uses the golden ratio rather than the modulo function to map the final location of the data, resulting in many fewer instances of collisions like these while also being much faster. It also appears to do a better job of using the smaller fixed-size set more evenly as a consequence of being based around Fibonacci numbers, just as long as the input data doesn’t have a large number of Fibonacci numbers themselves.

Going through the math that [Malte] goes over in his paper shows that, at least as far as performing the mapping part of a hash function, the Fibonacci hash performs much better than integer modulo. Some of the comments mention that it’s a specific type of a more general method called multiplicative hashing. For those using hash functions in their code it might be worth taking a look at either way, and [Malte] admits to not knowing everything about this branch of computer science as well but still goes into an incredible amount of depth about this specific method. If you’re more of a newcomer to this topic, take a look at this person who put an enormous bounty on a bitcoin wallet which shows why reverse-hashing is so hard.

Game Boy PCB Assembled With Low-Cost Tools

April 22, 2025 by 13 Comments

As computers have gotten smaller and less expensive over the years, so have their components. While many of us got our start in the age of through-hole PCBs, this size reduction has led to more and more projects that need the use of surface-mount components and their unique set of tools. These tools tend to be more elaborate than what would be needed for through-hole construction but [Tobi] has a new project that goes into some details about how to build surface-mount projects without breaking the bank.

The project here is interesting in its own right, too: a display module upgrade for the classic Game Boy based on an RP2350B microprocessor. To get all of the components onto a PCB that actually fits into the original case, though, surface-mount is required. For that [Tobi] is using a small USB-powered hotplate to reflow the solder, a Pinecil, and a healthy amount of flux. The hotplate is good enough for a small PCB like this, and any solder bridges can be quickly cleaned up with some extra flux and a quick pass with a soldering iron.

The build goes into a lot of detail about how a process like this works, so if you’ve been hesitant to start working with surface mount components this might be a good introduction. Not only that, but we also appreciate the restoration of the retro video game handheld complete with some new features that doesn’t disturb the original look of the console. One of the other benefits of using the RP2350 for this build is that it’s a lot simpler than using an FPGA, but there are perks to taking the more complicated route as well.

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Restoration Of Six-Player Arcade Game From The Early 90s

April 21, 2025 by 9 Comments

Although the video game crash of the mid-80s caused a major decline in arcades from their peak popularity, the industry didn’t completely die off. In fact, there was a revival that lasted until the 90s with plenty of companies like Capcom, Midway, SEGA, and Konami all competing to get quarters, francs, loonies, yen, and other coins from around the world. During this time, Namco — another game company — built a colossal 28-player prototype shooter game. Eventually, they cut it down to a (still titanic) six-player game that was actually released to the world. [PhilWIP] and his associates are currently restoring one of the few remaining room-sized games that are still surviving.

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