- 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.
- Jack Parsons (Wikipedia)
John Whiteside Parsons (born Marvel Whiteside Parsons; October 2, 1914 – June 17, 1952) was an American rocket engineer, chemist, and Thelemite occultist. Associated with the California Institute of Technology (Caltech), Parsons was one of the principal founders of both the Jet Propulsion Laboratory (JPL) and the Aerojet Engineering Corporation. He invented the first rocket engine to use a castable, composite rocket propellant, and pioneered the advancement of both liquid-fuel and solid-fuel rockets.