65F02 Is An FPGA 6502 With A Need For Speed

September 10, 2025 by Tyler August 8 Comments

Does the in 65F02 “F” stand for “fast” or “FPGA”? [Jurgen] doesn’t know, but his drop-in replacement board for the 6502 and 65c02 is out there and open source, whatever you want it to stand for.

The “f” could easily be both, since at 100 MHz, the 65f02 is blazing fast by 6502 standards–literally 100 times the speed of the first chips from MOS. That speed comes from the use of a Spartan 6 FPGA core to implement the 6502 logic; making the “f” stand for “FPGA” makes sense, given that the CMOS version of the chip was dubbed the 65c02. The 65f02 is a tiny PCB containing the FPGA and all associated hardware that shares the footprint of a DIP-40 package, making it a drop-in replacement. A really fast drop-in replacement.

You might be thinking that that’s insane, and that (for example) the memory on an Apple ][ could never run at 100 MHz and so you won’t get the gains. This is both true, and accounted for: the 65F02 has an internal RAM “cache” that it mirrors to external memory at a rate the bus can handle. When memory addresses known to interact with peripherals change, the 65f02 slows down to match for “real time” operations.

The USB adapter board for programming is a great touch.

Because of this the memory map of the external machine matters; [Jurgen] has tested the Commodore PET and Apple ][, along with a plethora of German chess computers, but, alas, this chip is not currently compatible with the Commodore 64, Atari 400/800 or BBC Micro (or at least not tested). The project is open source, however, so you might be able to help [Jurgen] change that.

We admit this project isn’t totally new– indeed, it looks like [Jurgen]’s last update was in 2024– but a fast 6502 is just as obsolete today as it was when [Jurgen] started work in 2020. That’s why when [Stephen Walters] sent us the tip (via electronics-lab), we just had to cover it, especially considering the 6502’s golden jubilee.

We also recently featured a 32-bit version of the venerable chip that may be of interest, also on FPGA.

Reverse Engineering A Robot Mower’s Fence

September 10, 2025 by Jenny List 22 Comments

There are a variety of robot mower systems on the market employing different navigation methods, and [Eelco] has the story of how one of these was reverse engineered. Second hand Roomba lawnmowers kept appearing for very low prices without the electronics driving the buried-wire fence that keeps them from going astray. The story of their reverse engineering provides us with a handy insight into their operation.

The wire fence is a loop of wire in the ground, so it was modeled using a few-ohm resistor and the waveform across it from a working driver captured with an oscilloscope. The resulting 3 kHz waveform surprisingly to us at least doesn’t appear to encode any information, so it could be replicated easily enough with an ESP32 microcontroller. An LM386 audio amplifier drives the loop, and with a bit of amplitude adjustment the mower is quite happy in its fake fence.

Robot mower hacking has become quite the thing around here.

Using An MCU’s Own Debug Peripheral To Defeat Bootrom Protection

September 10, 2025 by Maya Posch 2 Comments

The patient hooked up for some reverse-engineering. (Credit: Caralynx, Twitter)

Released in July of 2025, the Tamagotchi Paradise may look somewhat like the late 90s toy that terrorized parents and teachers alike for years, but it’s significantly more complex and powerful hardware-wise. This has led many to dig into its ARM Cortex-M3-powered guts, including [Yukai Li] who recently tripped over a hidden section in the bootrom of the dual-core Sonix SNC73410 MCU that makes up most of the smarts inside this new Tamagotchi toy.

Interestingly, [Yukai] did see that the visible part of the bootrom image calls into the addresses that make up the hidden part right in the reset handler, which suggests that after reset this hidden bootrom section is accessible, just not when trying to read it via e.g. SWD as the hiding occurs before the SWD interface becomes active. This led [Yukai] to look at a way to make this ROM section not hidden by using the Cortex-M3’s standard Flash Patch and Breakpoint (FPB) unit. This approach is covered in the project’s source file.

With this code running, the FPB successfully unset the responsible ROM hide bit in the OSC_CTRL register, allowing the full bootrom to be dumped via SWD and thus defeating this copy protection with relatively little effort.

Heading image: PCB and other components of a torn-down Tamagotchi Paradise. (Credit: Tamagotchi Center)

The weaving is on the left, a microphoto of the chip die is on the right.

The 555 As You’ve Never Seen It: In Textile!

September 10, 2025 by Tyler August 12 Comments

The Diné (aka Navajo) people have been using their weaving as trade goods at least since European contact, and probably long before. They’ve never shied from adopting innovation: churro sheep from the Spanish in the 17th century, aniline dies in the 19th, and in the 20th and 21st… integrated circuits? At least one Navajo Weaver, [Marilou Schultz] thinks they’re a good match for the traditional geometric forms. Her latest creation is a woven depiction of the venerable 555 timer.

“Popular Chip” by Marilou Schultz. Photo courtesy of First American Art Magazine, via righto.com

This isn’t the first time [Marilou] has turned an IC into a Navajo rug; she’s been weaving chip rugs since 1994– including a Pentium rug commissioned by Intel that hangs in USA’s National Gallery of Art–but it’s somehow flown below the Hackaday radar until now. The closest thing we’ve seen on these pages was a beaded bracelet embedding a QR code, inspired by traditional Native American forms.

That’s why we’re so thankful to [VivCocoa] for the tip. It’s a wild and wonderful world out there, and we can’t cover all of it without you. Are there any other fusions of tradition and high-tech we’ve been missing out on? Send us a tip.

FLOSS Weekly Episode 846: Mastering Embedded Linux Programming

September 10, 2025 by Jonathan Bennett 2 Comments

This week Jonathan and Dan chat with Frank Vasquez and Chris Simmonds about Embedded Linux, and the 4th edition of the Mastering Embedded Linux Programming book. How has this space changed in the last 20 years, and what’s the latest in Embedded Linux?

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Everything In A Linux Terminal

September 10, 2025 by Al Williams 49 Comments

Here at Hackaday Central, we fancy that we know a little something about Linux. But if you’d tasked us to run any GUI program inside a Linux terminal, we’d have said that wasn’t possible. But, it turns out, you should have asked [mmulet] who put together term.everything.

You might be thinking that of course, you can launch a GUI program from a terminal. Sure. That’s not what this is. Instead, it hijacks the Wayland protocol and renders the graphics as text. Or, if your terminal supports it, as an image. Performance is probably not your goal if you want to do this. As the old saying goes, “It’s not that the dog can sing well; it’s that the dog can sing at all.”

If, like us, you are more interested in how it works, there’s a write up explaining the nuances of the Wayland protocol. The article points out that Wayland doesn’t actually care what you do with the graphical output. In particular, “… you could print out the graphics and give them to a league of crochet grandmas to individually tie together every single pixel into the afghan of legend!” We expect to see this tested at an upcoming hacker conference. Maybe even Supercon.

We generally don’t like Wayland very much. We use a lot of hacks like xdotool and autokey that Wayland doesn’t like. We also think people didn’t understand X11’s network abilities until it was too late. If you think of it as only a video card driver, then you get what you deserve. But we have to admit, we are humbled by term.everything.

Bare Metal STM32: The Various Real Time Clock Flavors

September 10, 2025 by Maya Posch 8 Comments

Keeping track of time is essential, even for microcontrollers, which is why a real-time clock (RTC) peripheral is a common feature in MCUs. In the case of the STM32 family there are three varieties of RTC peripherals, with the newest two creatively called ‘RTC2′ and RTC3’, to contrast them from the very basic and barebones RTC that debuted with the STM32F1 series.

Commonly experienced in the ubiquitous and often cloned STM32F103 MCU, this ‘RTC1’ features little more than a basic 32-bit counter alongside an alarm feature and a collection of battery-backed registers that requires you to do all of the heavy lifting of time and date keeping yourself. This is quite a contrast with the two rather similar successor RTC peripherals, which seem to insist on doing everything possible themselves – except offer you that basic counter – including giving you a full-blown calendar and today’s time with consideration for 12/24 hour format, DST and much more.

With such a wide gulf between RTC1 and its successors, this raises the question of how to best approach these from a low-level perspective.

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