Chinese Abacus. The abacus is first known in China from the Northern Song dynasty through the work of Shao Yong (1011-1077). Like many early inventions it is not clear precisely where it originally came from. Some say Central Asia; some Asia Minor and others China.
Snag(noun) a stump or base of a branch that has been lopped off; a short branch, or a sharp or rough branch; a knot; a protuberance. Snag(noun) a tooth projecting beyond the rest; contemptuously, a broken or decayed tooth.
Scalar network analyzer (SNA): The scalar network analyzer, SNA is a form of RF network analyzer that only measures the amplitude properties of the device under test - i.e. its scalar properties. In view of this it is the simpler of the various types of analyser. Read more .