- The Z-80 has a 4-bit ALU. Here’s how it works. (righto.com)
The 8-bit Z-80 processor is famed for use in many early personal computers such the Osborne 1, TRS-80, and Sinclair ZX Spectrum, and it is still used in embedded systems and TI graphing calculators. I had always assumed that the ALU (arithmetic-logic unit) in the Z-80 was 8 bits wide, like just about every other 8-bit processor. But while reverse-engineering the Z-80, I was shocked to discover the ALU is only 4 bits wide! The founders of Zilog mentioned the 4-bit ALU in a very interesting discussion at the Computer History Museum, so it’s not exactly a secret, but it’s not well-known either.
- How Animals See the World (artsandculture.google.com)
Each type of animal on Earth has evolved a range of senses and skills which allow it to live successfully in its environment. Many of these adaptations are very different from how humans have evolved, and compared to humans some of these adaptations feel like they belong in a superhero comic. Senses such as ultraviolet vision, extra color receptors, and echolocation are very hard for humans to imagine, yet are part of the everyday life of hundreds of species of animals.