Hardware: Intel 8086, Arduino, Raspberry Pi
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Reverse-engineering the multiplication algorithm in the Intel 8086 processor
In this blog post, I explain the multiplication process inside the 8086, analyze the microcode that it used, and discuss the hardware circuitry that helped it out.3 My analysis is based on reverse-engineering the 8086 from die photos. The die photo below shows the chip under a microscope. I've labeled the key functional blocks; the ones that are important to this post are darker. At the left, the ALU (Arithmetic/Logic Unit) performs the arithmetic operations at the heart of multiplication: addition and shifts. Multiplication also uses a few other hardware features: the X register, the F1 flag, and a loop counter. The microcode ROM at the lower right controls the process.
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How was your Pi Day?
Greetings. I trust you had a splendid March 14th or, if you’re one of us, Pi Day, yesterday. Yes, we know it doesn’t really work unless you use the American date format, but for one day a year, we’re glad our friends across the pond put the day and the month the wrong way round. Just for the one day.
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James Bruton’s robot centipede of many legs
Bruton built this centipede robot as a scaled-down prototype, as he plans to construct a ridable version sometime in the future. This robot, which is still quite large, let him test the unusual walking mechanisms. The robot has five segments, each of which contains two pairs of legs. The mathematicians among you will have deduced that that equals 20 individual legs. But the legs don’t operate independently. In fact, all 20 of those legs are connected mechanically. Each segment has a drive shaft that moves its legs through gears and linkages, and universal joints connect the drive shafts between segments.
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Smart bedside mat won’t let you snooze your alarm
This is a small mat designed to sit by the user’s bed. When the alarm goes off in the morning, the user must get out of bed and stand on that mat for five to 10 seconds. Until they do so, the alarm will continue blaring. Snooze is not an option here and the simple act of getting out of bed and standing up should be enough for most people to shake the sleep off, ensuring that they won’t fall back asleep. Best of all, this is affordable and easy to build.