Lynn Korwatch located on top of Telegraph Hill. George F. Sweeney and Theodore F. Baugh were the two individuals to present the idea of a wooden semaphore on top of Telegraph Hill. A semaphore is a system in which one uses two flags or poles and sends signals in an alphabetic code. Sweeney and Baugh expanded their system by placing a signal station on Point Lobos, which is located 20–30 miles from port in San Francisco. The reasoning behind this was that there was high demand from people wanting to know when the ships were arriving at an earlier time so that
Two-out-of-five code zero. The IBM 7070, IBM 7072, and IBM 7074 computers used this code to represent each of the ten decimal digits in a machine word, although they numbered the bit positions 0-1-2-3-4, rather than with weights. Each word also had a sign flag, encoded using a two-out-of-three code, that could be A Alphanumeric, − Minus, or + Plus. When copied to a digit, the three bits were placed in bit positions 0-3-4. (Thus producing the numeric values 3, 6 and 9, respectively.) A variant is the U.S. Post Office POSTNET barcode, used to represent the ZIP+4 code for automated mail