Explore the Guts of Computing With Arith-matic’s S1-AU Kit

This 4-bit arithmetic logic unit looks great and teaches important lessons about computing

4 min read
Photo of a handheld ALU.
Photo: Randi Klett

gifFour-bit Action: This handheld ALU has two internal registers to hold numbers for addition and subtraction. The result can also be fed back into a register to accumulate arithmetic results, and flags test for conditions such as a zero.Gif: Randi Klett

I don’t normally review Kickstarter projects that haven’t reached the verified shipping stage. Even when they manage to hit their targets, too many times I’ve seen crowd-funded projects flame out for various reasons. Such causes might be a high-minded concept that pushes the available technology beyond feasibility, problems with the harsh realities of manufacturing, or occasional outright malfeasance, where money is taken for projects that exist only as vaporware.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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