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  2. History of timekeeping devices - Wikipedia

    en.wikipedia.org/wiki/History_of_timekeeping_devices

    An Egyptian method of determining the time during the night, used from at least 600 BC, was a type of plumb-line called a merkhet. A north–south meridian was created using two merkhets aligned with Polaris, the north pole star. The time was determined by observing particular stars as they crossed the meridian. [24]

  3. History of computing hardware - Wikipedia

    en.wikipedia.org/wiki/History_of_computing_hardware

    The first of three programs written for the machine found the highest proper divisor of 2 18 (262,144), a calculation that was known would take a long time to run—and so prove the computer's reliability—by testing every integer from 2 18 − 1 downwards, as division was implemented by repeated subtraction of the divisor.

  4. Unix time - Wikipedia

    en.wikipedia.org/wiki/Unix_time

    Unix time is currently defined as the number of non-leap seconds which have passed since 00:00:00 UTC on Thursday, 1 January 1970, which is referred to as the Unix epoch. [ 3] Unix time is typically encoded as a signed integer . The Unix time 0 is exactly midnight UTC on 1 January 1970, with Unix time incrementing by 1 for every non-leap second ...

  5. Pascal's calculator - Wikipedia

    en.wikipedia.org/wiki/Pascal's_calculator

    Pascal's calculator (also known as the arithmetic machine or Pascaline) is a mechanical calculator invented by Blaise Pascal in 1642. Pascal was led to develop a calculator by the laborious arithmetical calculations required by his father's work as the supervisor of taxes in Rouen. [ 2] He designed the machine to add and subtract two numbers ...

  6. Sexagesimal - Wikipedia

    en.wikipedia.org/wiki/Sexagesimal

    The Parisian version of the Alfonsine tables (ca. 1320) used the day as the basic unit of time, recording multiples and fractions of a day in base-60 notation. [8] The sexagesimal number system continued to be frequently used by European astronomers for performing calculations as late as 1671. [9]

  7. Stepped reckoner - Wikipedia

    en.wikipedia.org/wiki/Stepped_reckoner

    The stepped reckoner or Leibniz calculator was a mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz (started in 1673, when he presented a wooden model to the Royal Society of London [2] and completed in 1694). [1] The name comes from the translation of the German term for its operating mechanism, Staffelwalze ...

  8. System time - Wikipedia

    en.wikipedia.org/wiki/System_time

    System time. In computer science and computer programming, system time represents a computer system's notion of the passage of time. In this sense, time also includes the passing of days on the calendar . System time is measured by a system clock, which is typically implemented as a simple count of the number of ticks that have transpired since ...

  9. Mean time between failures - Wikipedia

    en.wikipedia.org/wiki/Mean_time_between_failures

    Overview. Mean time between failures (MTBF) describes the expected time between two failures for a repairable system. For example, three identical systems starting to function properly at time 0 are working until all of them fail. The first system fails after 100 hours, the second after 120 hours and the third after 130 hours.