- ‘There is a certain place where the scorpion with his tail and curving claws sprawls across two signs of the zodiac’, wrote Ovid in his Metamorphoses. He was referring to the ancient Greek version of Scorpius, which was much larger than the constellation we know today. The Greek scorpion was in two halves: one half, called Σκορπίος (Skorpios), contained its body and sting, while the front half comprised the claws. The Greeks called this front half Χηλαί (Chelae), which means ‘claws’. In the first century BC the Romans made the claws into a separate constellation, Libra, the balance.
passage through the ecliptic
- Star Tales - Ophiuchus (ianridpath.com)
Ophiuchus (pronounced off-ee-YOO-cuss) represents a man grasping a huge snake with both hands, the head of the snake in his left hand and its tail in his right hand. The snake is represented by a separate constellation, Serpens, which is unique among the 88 constellations in being divided into two halves, the head on one side of Ophiuchus and the tail on the other. The mythologists such as Aratus and Hyginus described the snake as being coiled around the waist of Ophiuchus, and that is how it was shown on early illustrations, including Dürer’s hemisphere of 1515; but from Bayer’s chart onwards it was usually shown passing either across his body or between his legs.
- How flip-flops are implemented in the Intel 8086 processor (righto.com)
A key concept for a processor is the management of “state”, information that persists over time. Much of a computer is built from logic gates, such as NAND or NOR gates, but logic gates have no notion of time. Processors also need a way to hold values, along with a mechanism to move from step to step in a controlled fashion. This is the role of “sequential logic”, where the output depends on what happened before. Sequential logic usually operates off a clock signal,1 a sequence of regular pulses that controls the timing of the computer. (If you have a 3.2 GHz processor, for instance, that number is the clock frequency.)