Devices: Linux and RTOS, pi3hat r4.5, LattePanda V1, and More
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What is real-time Linux? Part II
Welcome to this three-part mini-series on real-time Linux.
In Part I, we set the stage for the remainder of the series by defining a real-time system, and went through common misconceptions. We also covered the broad market applications of a real-time Linux kernel.
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pi3hat r4.5
I'm excited to announce a minor upgrade to the mjbots pi3hat product line, the pi3hat r4.5! This has a few upgrades over the old r4.4b: Check it out at mjbots.com today!
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LattePanda V1 - my experience with a Raspberry Pi alternative
Please note that my use cases are more on the software side, I did not try out the hardware capabilities that SBC-s are also associated with (GPIO, camera/display ports etc).
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Reverse-engineering the ModR/M addressing microcode in the Intel 8086 processor
I've been reverse-engineering the 8086 starting with the silicon die. The die photo below shows the chip under a microscope. The metal layer on top of the chip is visible, with the silicon and polysilicon mostly hidden underneath. Around the edges of the die, bond wires connect pads to the chip's 40 external pins. I've labeled the key functional blocks; the ones that are important to this discussion are darker and will be discussed in detail below. Architecturally, the chip is partitioned into a Bus Interface Unit (BIU) at the top and an Execution Unit (EU) below. The BIU handles bus and memory activity as well as instruction prefetching, while the Execution Unit (EU) executes instructions and microcode. Both units play important roles in memory addressing.
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Using HDMI radio interference for high-speed data transfer
This story, too, begins with noise. I was browsing the radio waves with a software radio, looking for mysteries to accompany my ginger tea. I had started to notice a wide-band spiky signal on a number of frequencies that only seemed to appear indoors. Some sort of interference from electronic devices, probably. Spoiler alert, it eventually led me to broadcast a webcam picture over the radio waves... but how?
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Linker notes on Power ISA
The terms "PowerPC" and "powerpc" remain popular in numerous places, including the powerpc-*-*-* and powerpc64-*-*-* in official target triple names. The abbreviation "PPC" ("ppc") is used in numerous places as well. For simplicity, I will refer to the 32-bit architecture as "PPC32" and the 64-bit architecture as "PPC64".
We will see how the lack of PC-relative addressing before Power10 has caused great complexity to the ABI and linkers.