Open Hardware, Retro, and Linux Devices
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Bald Engineer ☛ Measuring Apple II CPU's Glitchy Clock
The Apple II’s CPU clock has jitter or a glitch. This issue is not new—it has been present since its original design in 1977! Bald Engineer uses an oscilloscope to show how often the glitch occurs and how to correlate that jitter to its source—which is useful when you are not testing 40-year-old devices. The device under test (DUT) in this video is the Mega IIe project. It’s a fully compatible Apple IIe built around the Mega II chip.
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Michael Lynch ☛ Building My First Homelab Server Rack · mtlynch.io
A lot of home server enthusiasts buy server racks, but I never thought of myself as a rack guy. I wasn’t so into servers that I needed a whole rack; I just had a VM server here, a data server there. Maybe a few switches scattered around. Buying a rack meant admitting that I wasn’t just a casual home server guy but an intense homelab weirdo.
One day, I gave in and bought a rack, and I’m better for it. It makes my servers more pleasant to work with and eliminates my sprawling mess of wires.
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Raspberry Pi ☛ HATs and bonnets to give your Raspberry Pi 400 a cyberdeck feel
The HAT and Bonnet feature a few STEMMA connectors so you can easily plug in some NeoPixels or speakers, depending on what you’re cooking. They work with many more things than just a screen, but using them with a screen and your Raspberry Pi 400 is when they have that cyberdeck look, and why they were so named. My favourite feature is the custom-made angled headers so the HAT and Bonnet will sit slightly tipped back at a comfortably readable angle while you’re working. We do so appreciate when our friends at Adafruit care about our spinal health.
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Bald Engineer ☛ Picking I2C Pull-Up Resistors (Correctly)
A long time ago, I made a video suggesting math was unnecessary to determine proper pull-up resistor values. Like most generalized statements, that suggestion is not always true. For example, in data buses like I2C, speeds like 400 kHz and 1 MHz are common. At those speeds, the pull-up resistor and the bus capacitance form an RC filter that fundamentally limits the data transmission speed. Or. It limits the range of pull-up resistor values. In this Workbench Wednesdays video, I show how to estimate I2C bus capacitance, measure that capacitance, and pick pull-up resistor values.
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Linux Gizmos ☛ Noni Radio Module with Qualcomm’s Chipsets for WiFi-7 Connectivity
The Noni module, leveraging Qualcomm’s QCA9274/QCA6274 chipsets, provides advanced WiFi-7 connectivity in a versatile M.2 A+E form factor. Designed for a wide spectrum of applications, it operates efficiently across both commercial and industrial temperature ranges, ensuring reliable performance in multiple scenarios.