Strictly useless and completely delightful: decoding QR codes by hand, error correction and all. It is the same pleasure as reading a hex dump, and you come away understanding what the little squares are actually doing. The human-readable QR variant at the end is a fun twist.

A buried crater off the English coast that geologists voted against in 2009 turns out to be the real thing after all. The clinching evidence came from shocked quartz in old oil-well rock cuttings, which is a lovely example of industrial leftovers settling a scientific argument. Close enough to the Dutch coast to count as neighbourhood news, give or take 45 million years.

Ken Shirriff is back at the die photos, this time walking through the 8087's add and subtract microcode line by line. Systems people will enjoy the two-pass normalisation scheme and the candid description of the special-case handling as spaghetti. It is a reminder that IEEE floating point was hard-won silicon before it was a standard.

Archaeology with a wagging tail. The clever detail is that hairless dogs lack certain teeth because of the same gene, so even bare bones can reveal the breed. The diet results suggest these pups were fed more like children than like the other dogs.

Every kernel hacker's archaeology dream: someone cleans out a room and finds a nine-track reel labelled with what may be the only surviving copy of Fourth Edition UNIX, the first one mostly rewritten in C. The story is worth it for the reminder of how much of our history lives on fragile media in forgotten cupboards.

Before anyone had a stored program, people were summing sine waves with pulleys and a wire to print a year of tides in under half an hour. It is a lovely piece of special-purpose hardware, and the American one, nicknamed Old Brass Brains, stayed in service into the 1960s.