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A pinwheel calculator is a class of mechanical calculator described as early as 1685, and popular in the 19th and 20th century, calculating via wheels whose number of teeth were adjustable. These wheels, also called pinwheels, could be set by using a side lever which could expose anywhere from 0 to 9 teeth, and therefore when coupled to a ...
It was the first calculator that could perform all four basic arithmetic operations. [ 3 ] Its intricate precision gearwork, however, was somewhat beyond the fabrication technology of the time; mechanical problems, in addition to a design flaw in the carry mechanism, prevented the machines from working reliably.
A rotary dial combination padlock. A rotary combination lock is a lock commonly used to secure safes and as an unkeyed padlock mechanism. This type of locking mechanism consists of a single dial which must be rotated left and right in a certain combination in order to open the lock.
A Wordlock letter combination lock.. A combination lock is a type of locking device in which a sequence of symbols, usually numbers, is used to open the lock. The sequence may be entered using a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed symbols which directly interact with the locking mechanism, or through an ...
A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them Curta Type I calculator, top view Curta Type I calculator, bottom view. The Curta is a hand-held mechanical calculator designed by Curt Herzstark. [1] It is known for its extremely compact design: a small cylinder that fits in the palm of the hand.
Friden made a calculator that also provided square roots, basically by doing division, but with added mechanism that automatically incremented the number in the keyboard in a systematic fashion. The last of the mechanical calculators were likely to have short-cut multiplication, and some ten-key, serial-entry types had decimal-point keys.
Another student was recruited by a classmate who inquired if “they wanted to do some work and make some money for work” before they went with the friend to Smith’s residence and later had ...
The key contains a power supply device, usually a rechargeable battery or a replaceable battery in the key, used to drive the system to work; it also includes an electronic storage and control device for storing the identification code of the lock. The software is used to set and modify the data of each key and lock. [2]