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Wednesday, August 5, 2026

ColourfieldsOver on the (inexplicably login-walled) site "NewEnigma," Keith Austin [writes](https://www.newenigma.com/enigma/view/1277/Colourfields): > Draw a 4-by-4 grid. Colour each square red or blue. Select any square, S, and write 1 in it. > Then write 1 in every square you can reach from S by a series of moves, where each move is from > a square to an adjacent, horizontally, vertically, or diagonally, square of the same colour [...] In brief: What is the maximum number of _queenwise-connected_ monochromatic regions you can make by coloring each square of an $$n\times n$$ grid either red or blue?๐Ÿ“Arthur Oโ€™Dwyer

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Tuesday, August 4, 2026

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Friday, July 31, 2026

Kinton Fordโ€™s _Canto I_In โ€œVaraldoโ€™s Shahrazad and Chitiโ€™s Centunesimo Cantoโ€ (2025-08-11) I mentioned the existence of a lipogrammatic translation of Canto I of Danteโ€™s Inferno performed by one Kinton Ford (a pseudonym, as far as I know) for Rick Whitakerโ€™s now-defunct literary e-zine Exquisite Pandemic (2020โ€“2021). A year later, seeing itโ€™s still unavailable anywhere else online, I feel justified in preserving that whole tour-de-force here for posterity.๐Ÿ“Arthur Oโ€™Dwyer

Thursday, July 30, 2026

Fixing a super 8 projector from the 70sWarning! Do not try any of this at home! Messing with internals of electronic devices is dangerous and can lead to electrical fires, serious injury and even loss of life. My dad started using a super 8 film camera as early as 1967 (the system was launched in 1965). He stopped doing it in the 1980s as it became pretty much impossible to buy film. Ever since then the films have been stored in multiple cardboard boxes in his basement. Recently he moved to a smaller apartment so all the films and related hardware had to go somewhere else. Namely, to me. Here is a representative sample. The picture does really not make justice to the projector. It is perhaps the only household appliance I have ever owned that could survive a head-on collision with an IBM Thinkpad from the 2000s. The projector weighs 10 kilos and consumes 200 watts when running, half of which is taken by its halogen light bulb. For comparison a typical modern LED light bulb consumes less than 5 watts. The projector has not been used this millennium so unsurprisingly it did nothing when I plugged it in. The back cover could be opened (with a screwdriver) revealing two glass fuses, one of which was burnt. I replaced it and plugged the machine back in. It immediately let loose the magic smoke even though everything was turned off. Fortunately I had kept the back cover open so could see the smoke the second it appeared and managed to cut the power before flames appeared. Unfortunately the smoke originated deep inside the machine so I could not see which component was the source. To get deeper I would have to remove all the covers. That is no small feat, mind you, I had to buy a whole new ratchet set to get all the various screws out. This thing predates printed circuit boards that would tell you which holes belong to which components. Instead all components have been soldered to the board by hand with Japanese meticulousness. The board won't give us any help on deciphering how things should work. Visual inspection also does not reveal any immediately broken components. Neither did poking around with a multimeter. The only life line was that even though a component had started smoking the fuse had not blown. In theory I could plug the machine in for a second and see if smoke appears again. If it does I can see the exact faulty component. At this point I'd like to remind you of the warning at the top of the post. If you have a known broken electrical device, you should never connect it to any sort of a power source. Seek advice from a qualified professional instead. Even if you manage not to burn your house down, electric shocks are nasty and any resulting smoke is almost certainly noxious. Anyhow, after taking sufficient precautions I plugged it back in and immediately got smoke and could decipher what was wrong. One of the main electrolytic capacitors (the one that was in the most inconvenient location, obviously) had dried out and shorted. This caused one of the bridge rectifiers to have its positive and negative output leads short circuited. Here are the problematic components. The dark blue capacitor on the right is the broken one. For some weird reason the three decoupling capacitors have different voltage ratings (16V, 25V and 50V) even though there is only one transformer and input voltage (12 V). The black circles are the bridge rectifiers. The one on the right is the broken one. In this picture the cracks are fairly visible but trying to detect them in person is very difficult, even with a magnifying glass and a flashlight. According to multimeter measurements the other two capacitors and rectifier are working, but it's better to replace all of them. 50 year old eletrolytic capacitors have a short life expectancy and the additional work needed to fix all instead of only one is insignificant. Here is a comparison shot of the old components and their modern replacements. After soldering in the new components you enter a paranoid session of measuring every possible combination on the board to ensure you have not accidentally created a short or put any of the components in the wrong way. A failure here is silent and can give you a live Electroboom experience in your own home. Even though it sounds exciting, you really don't want to see it with your own eyes. I don't speak from experience here, and intend to keep it that way. Anyhow, eventually you have to plug the power and try if the machine works. Amazingly enough it did without a hitch. Once you have it running you can truly appreciate how well the mechanical parts of the projector have been designed. It runs silent, smooth and with zero visible jitter. There is only one plastic knob in the entire device. Unfortunately it is the lens focus adjustment wheel, and it has broken off (as you can see in the first image). You can still sort of twist it with your fingers but the experience is inconvenient to say the least. What next? An obvious question some of you might have is "Wouldn't it be more convenient to watch films on a computer than an ancient and potentially deadly projector?" The answer to that is "Yes, it would indeed be." But more on that in a future blog post.๐Ÿ“Nibble Stew
CUDA meets Windows on ARM64: getting your applications ready for NVIDIA RTX Spark with ConanWindows on ARM just got a lot more interesting for developers building local AI agents and creators pushing GPU-accelerated workflows. With NVIDIA RTX Spark bringing CUDA-capable silicon to ARM64 laptops and devices, and NVIDIA shipping the CUDA Toolkit 13.4 developer preview โ€” the first CUDA release with a compiler and device libraries that target Windows 11 on ARM64 โ€” the door is now open for CUDA-accelerated applications to run natively on this platform. The remaining question for most teams is: how do you actually plug this into your build? Today weโ€™re excited to show you that with cuda-conan , the answer is the same as itโ€™s always been with Conan โ€” add a requirement, and go. CUDA 13.4 is currently a developer preview , made available by NVIDIA so that developers can start porting their applications ahead of general availability. See NVIDIAโ€™s release notes for details. cuda-conan is a recipes only repository, no binaries are provided. Building packages from these recipes downloads the CUDA Toolkit and other NVIDIA components as made available by NVIDIA, subject to NVIDIAโ€™s own terms, including any applicable EULAs. Why this matters NVIDIA RTX Spark and the broader wave of ARM-powered Windows devices represent a real shift in where GPU-accelerated applications need to run. In order to take advantage of ARM64 native performance as well as the integrated GPU acceleration, your CUDA applications will need to be rebuilt for the new platform. And until now, there hasnโ€™t been a great way to use CUDA as a dependency without cobbling together manual toolkit installs and fragile environment setups โ€” something that gets even messier the moment you want to cross-build from an x86_64 CI runner instead of testing on physical ARM64 hardware. The recipes and features of cuda-conan close that gap. The recipes in the repository automate the download of the CUDA Toolkit, along with related libraries like cuDNN and TensorRT, so that you can use them as any other dependencies. Conan will configure your build, ensure compatible binaries, and expose the right environment when running your programs. Windows and Linux are supported, including cross-building for Jetson devices โ€” and now, for the first time, the developer preview makes it possible to target Windows ARM64 as well, including cross-building from x86_64 Windows. CUDA as just another dependency First, configure the cuda-conan remote: git clone https://github.com/conan-io/cuda-conan conan remote add cuda-conan ./cuda-conan If you already use Conan, thatโ€™s the only setup required. From there on, adding CUDA is just another entry in your conanfile.py : def requirements ( self ): self . requires ( "cuda-toolkit/[>=13 ) self . tool_requires ( "cuda-toolkit/ " ) Thatโ€™s it โ€” the same two lines work for every platform CUDA supports, whether youโ€™re building natively or cross-compiling. Your CMakeLists.txt needs no Conan-specific changes either, and can follow standard CMake practice: enable_language ( CUDA ) find_package ( CUDAToolkit ) Conan resolves and provides the toolkit, and find_package(CUDAToolkit) finds it. No system-wide CUDA install, no environment variables pointing at a specific CUDA installation, nothing extra to configure in CI beyond having Conan available. In your profile, set the GPU architecture(s) youโ€™re targeting. Please refer to the CUDA reference documentation to work out the GPU architecture for the device you are targetting. As an example: tools.cmake.cmaketoolchain:extra_variables*={'CMAKE_CUDA_ARCHITECTURES':'87-real'} And for the rest of your dependencies? Conan Center already builds and supports over 800 libraries for Windows ARM64 , so chances are your stack is already covered โ€” see Windows ARM64 builds now enabled in Conan Center for the full story. No ARM64 hardware? No problem One of the best parts of this setup is that you donโ€™t need an ARM64 machine to get started in order to start porting your applications. Cross-compiling for Windows ARM64 works directly from your existing x86_64 workstations or CI runners. If your Conan profile is already set up for msvc , cross-building is as simple as adding --settings arch=armv8 to your Conan command (e.g. create or install ): conan create . --settings arch=armv8 Under the hood, Conan makes sure nvcc runs on your x86_64 build machine while linking ARM64 CUDA libraries into your application โ€” so the executable you get out the other end is ready to run on RTX Spark and other ARM64 devices, no emulation required. Before you build, there are a couple of one-time setup steps: A recent Conan 2 (>=2.31.1 recommended) Visual Studio 2022 or 2026 with the ARM64 MSVC toolset installed (via the Visual Studio Installer โ†’ Individual components โ†’ search โ€œARM64โ€ โ†’ select the C++ ARM64 build tools for your version). This is required for both native and cross builds โ€” see ARM64 Visual Studio is officially here! Seeing it in action: cuda-samples Talk is cheap โ€” letโ€™s build something. cuda-samples is NVIDIAโ€™s own collection of example CUDA applications, from minimal ones like vectorAdd and deviceQuery up through CUDA library usage (cuBLAS, cuFFT, and more). cuda-conan ships a recipe that builds it from source with CUDA from Conan, ARM64 included. git clone https://github.com/conan-io/cuda-conan conan remote add cuda-conan ./cuda-conan cd cuda-conan/samples/cuda-samples conan build . --settings arch=armv8 -c tools.cmake.cmaketoolchain:generator=Ninja --build=missing -cc core.version_ranges:resolve_prereleases=True Drop --settings arch=armv8 and it builds natively for x86_64 instead โ€” same command, same recipe, either target. Once itโ€™s built, load the run environment and try it out: cmd.exe /k "build\Release\generators\conanrun.bat" build\Release\cpp\1_Utilities\deviceQuery\deviceQuery.exe If you donโ€™t have an NVIDIA-powered ARM64 device on hand yet, thatโ€™s fine โ€” the binary will still run, and simply report that cudaGetDeviceCount couldnโ€™t find a device. The big one: llama.cpp with CUDA support for RTX Spark Hereโ€™s where it gets fun. llama.cpp is the dependency-light C/C++ inference engine behind a huge chunk of the local-LLM ecosystem โ€” over 80k stars on GitHub, and the engine powering downstream projects like Ollama and LM Studio. Getting it running with CUDA acceleration on Windows ARM64 is exactly the kind of workload RTX Spark exists for: local, GPU-accelerated AI inference on an ARM64 PC. cuda-conan includes a recipe for it too, CUDA and Windows ARM64 support included: cd samples/llama-cpp conan create all --version=b6565 -pr clang-cl-arm64 --build=missing -cc core.version_ranges:resolve_prereleases=True This same command runs on both x86_64 and ARM64 Windows. Want a different GPU architecture target? Just edit the profile at samples/llama-cpp/clang-cl-common . Windows ARM64 builds of llama.cpp currently require building with Clang ( clang-cl ) rather than MSVCโ€™s cl.exe . Install it via the Visual Studio Installer: Individual components โ†’ search โ€œClangโ€ โ†’ select the C++ Clang Compiler for Windows component. Developing for other platforms? Weโ€™ve got you covered too Windows ARM64 is the new addition, but cuda-conan isnโ€™t a one-platform trick. The same recipes support Linux on both x86_64 and armv8, and have been tested on Jetson devices running JetPack 7.2 with CUDA 13.2 โ€” so if your CUDA workloads are headed for embedded or edge deployments rather than a Windows laptop, the same requirements and workflow shown above apply there too. The samples go beyond cuda-samples and llama.cpp as well: cuda-conan also ships recipes for other heavily requested CUDA-accelerated libraries, including libtorch and onnxruntime , so you can pull in the frameworks powering most AI workloads today without building them yourself. Where things stand today This is a fast-moving space, so a couple of things to keep in mind: CUDA support at runtime can only be verified on actual NVIDIA-powered ARM64 hardware โ€” the ARM64 binaries themselves will run on any Windows on ARM device. Right now, cuda-toolkit 13.4 preview is the only package available. Other libraries, like cuDNN, will follow as NVIDIA makes them publicly available for this platform. Try it out The CUDA Toolkit landing on Windows ARM64, right as NVIDIA RTX Spark brings capable silicon to ARM64 PCs, is a genuinely exciting moment for GPU developers โ€” and with Conan, adopting it doesnโ€™t require reworking your build. Two lines in your conanfile.py , and youโ€™re building for a whole new class of device. Clone cuda-conan , try the samples, and let us know how it goes: Repository Readme Building CUDA-enabled applications for Windows 11 on ARM (NVIDIA RTX Spark) Report issues or share feedback Roadmap discussion โ€” see whatโ€™s coming next Happy coding! This post was written with AI assistance and reviewed by humans.๐Ÿ“Conan C/C++ Package Manager Blog