- Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC
- These true- and false-color images of central Canada show the Great Slave Lake in the Northwest Territories (top) and Lake Athabasca to the southeast. Lake Athabasca straddles the border between Alberta (west) and Saskatchewan (east). A fire (red dot) is burning in Saskatchewan, and the snow capped Rocky Mountains cut through southwest Alberta at bottom left. In the false-color image, vegetation is green, water is dark blue, and ice (or snow) is light blue.
- 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.
