Binary Math Tricks: Shifting To Divide By Ten Ain’t Easy

June 12, 2020 by Al Williams 52 Comments

On small CPUs, you often don’t have a multiply or divide instruction. Of course, good programmers know that shifting right and left will multiply or divide by a power of two. But there are always cases where you need to use something that isn’t a power of two. Sometimes you can work it out for multiplication.

For example, multiplying by 10 is common when dealing with conversion between binary and decimal. But since 10n is equal to 8n+2n, you can express that as a bunch of left shift three times to multiply by eight, adding that value to your original value shifted left once to multiply by two.

But division is a different problem. n/10 does not equal n/8-n/2 or anything else simple like that. The other day a friend showed me a very convoluted snippet of code on Stack Overflow by user [realtime] that divides a number by 10 and wanted to know how it worked. It is pretty straightforward if you just stick with the math and I’ll show you what I mean in this post. Turns out the post referenced the venerable Hacker’s Delight book, which has a wealth of little tricks like this.

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Quantum Computing And The End Of Encryption

June 11, 2020 by Maya Posch 58 Comments

Quantum computers stand a good chance of changing the face computing, and that goes double for encryption. For encryption methods that rely on the fact that brute-forcing the key takes too long with classical computers, quantum computing seems like its logical nemesis.

For instance, the mathematical problem that lies at the heart of RSA and other public-key encryption schemes is factoring a product of two prime numbers. Searching for the right pair using classical methods takes approximately forever, but Shor’s algorithm can be used on a suitable quantum computer to do the required factorization of integers in almost no time.

When quantum computers become capable enough, the threat to a lot of our encrypted communication is a real one. If one can no longer rely on simply making the brute-forcing of a decryption computationally heavy, all of today’s public-key encryption algorithms are essentially useless. This is the doomsday scenario, but how close are we to this actually happening, and what can be done?

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The Seedy World Of Message Serialization

June 10, 2020 by Kerry Scharfglass 26 Comments

Look, I’ve been there too. First the project just prints debug information for a human in nice descriptive strings that are easy to understand. Then some tool needs to log a sensor value so the simple debug messages gain structure. Now your debug messages {{look like : this}}. This is great until a second sensor is added that uses floats instead of ints. Now there are sprinklings of even more magic characters between the curly braces. A couple days later and things are starting to look Turing complete. At some point you look up and realize, “I need a messaging serialization strategy”. Well you’ve come to the right place! Continue reading “The Seedy World Of Message Serialization” →

Bertha Benz Pushed The Automobile Toward Production

June 9, 2020 by Kristina Panos 25 Comments

Who invented the automobile? The answer depends a little bit on your definition of the word. The first practical gas-powered carriage was built by Karl Benz, who later merged his company with Daimler Motor Group to form Mercedez-Benz.

Karl Benz was a design visionary whose first fascinations were with locomotives and bicycles. His 1886 Benz Patent Motorwagen was the first automobile to generate its own power, which was made with a two-stroke engine and transmitted to the rear axle by a pair of chains. He didn’t think it was ready for the road, and he was mostly right.

Bertha Benz, Karl’s wife and business partner, believed in her husband’s invention. She had been there since the beginning, and provided much of the funding for it along the way. If she hadn’t taken it out for a secret, illegal joyride, the Motorwagen may have never left the garage.

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3D Printing Nuclear Reactors For Fun And Profit

June 8, 2020 by Maya Posch 18 Comments

Over the past decades, additive manufacturing (AM, also known as 3D printing) has become increasingly common in manufacturing processes. While immensely helpful in the prototyping of new products by allowing for rapid turn-around times between design and testing, these days additive manufacturing is used more and more often in the production of everything from small production runs of custom enclosures to hard to machine components for rocket engines.

The obvious advantage of additive manufacturing is that they use generic equipment and common materials as input, without requiring expensive molds as in the case of injection molding, or extensive, wasteful machining of raw materials on a lathe, mill, and similar equipment. All of the manufacturing gets reduced to a 3D model as input, one or more input materials, and the actual device that converts the 3D model into a physical component with very limited waste.

In the nuclear power industry, these benefits haven’t gone unnoticed, which has led to 3D printed parts being developed for everything from keeping existing plants running to streamlining spent fuel reprocessing and even the printing of entire nuclear reactors.

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Ancient History Of The Phone Jack

June 5, 2020 by Al Williams 67 Comments

While watching a video about old radios from the 1920s, a phone jack popped up. The host mentioned that phone jacks are super old and he wondered what was their origin. I always assumed they had something to do with the telephone system, and that’s right, but I had no idea how old they really are and how they’ve evolved. Turns out the venerable plug goes back to at least 1878.

Keep in mind, I’m talking about the good old fashioned 1/4″ phone jack with two wires. Over time, the jack and plug have spawned different versions with more wires and — particularly — smaller dimensions. The headphone jack that many smartphone makers are dropping is a direct descendant of that old phone jack. But a mono cable like you would see connecting an electric guitar or another mono source would be right at home connected to a 1900s switchboard. Let’s take a look at the origins of a design that’s almost 150 years old and still in use.

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Netbooks: The Form Factor Time Forgot

June 4, 2020 by Zoe Skyforest 172 Comments

Long ago, before smartphones were ubiquitous and children in restaurants were quieted with awful games on iPads, there was a beautiful moment. A moment in which the end user could purchase, at a bargain price, an x86 computer in a compact, portable shell. In 2007, the netbook was born, and took the world by storm – only to suddenly vanish a few years later. What exactly was it that made netbooks so great, and where did they go?

A Beautiful Combination

An Asus EEE PC shown here running Linux. You could run anything on them! Because they were real, full-fat computers. No locked down chipsets or BIOS. Just good, clean, x86 fun.

The first machine to kick off the craze was the Asus EEE PC 701, inspired by the One Laptop Per Child project. Packing a 700Mhz Celeron processor, a small 7″ LCD screen, and a 4 GB SSD, it was available with Linux or Windows XP installed from the factory. With this model, Asus seemed to find a market that Toshiba never quite hit with their Libretto machines a decade earlier. The advent of the wireless network and an ever-more exciting Internet suddenly made a tiny, toteable laptop attractive, whereas previously it would have just been a painful machine to do work on. The name “netbook” was no accident, highlighting the popular use case — a lightweight, portable machine that’s perfect for web browsing and casual tasks.

But the netbook was more than the sum of its parts. Battery life was in excess of 3 hours, and the CPU was a full-fat x86 processor. This wasn’t a machine that required users to run special cut-down software or compromise on usage. Anything you could run on an average, low-spec PC, you could run on this, too. USB and VGA out were available, along with WiFi, so presentations were easy and getting files on and off was a cinch. It bears remembering, too, that back in the Windows XP days, it was easy to share files across a network without clicking through 7 different permissions tabs and typing in your password 19 times.

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