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binary search

A technique for quickly locating an item in a sequential list. The desired key is compared to the data in the middle of a sequential index or in the middle of a sequential file. The half that contains the data is then compared in the middle, and so on, either until the key is located or a small enough group is isolated to be sequentially searched. See binary.



binary

Meaning two. The principle behind digital computers. All input to the computer is converted into binary digits that are either 0 or 1. For example, when you press the "A" key on your keyboard, the keyboard circuit generates and transfers the number 01000001 to the computer's RAM as a series of pulses with different voltages. The bits are stored as temporarily charged cells in RAM, as permanent charges in a solid state drive (SSD) or as microscopic magnets on a hard drive. The computer's display screen and printers convert the binary numbers into visual characters.

Circuits Are Binary
The electronic circuits that process these binary numbers are also binary in concept. They are made up of on/off switches (transistors) that are electrically opened and closed. The current flowing through one switch turns on (or off) another switch, and so on. These switches open and close in nanoseconds and picoseconds (billionths and trillionths of a second). See Boolean logic.

Smaller Spots - Faster Switches
A computer's capability to do work is based on its workspace capacity (RAM), storage capacity (disk or SSD) and the speed of its circuits. Greater capacities are achieved by making the memory cells or magnetic spots smaller. Faster circuit speeds are achieved by shortening the time it takes to open and close the transistor (electronic switch). In order to increase computer performance, we keep improving binary technologies. See binary numbers, binary values, binary file, binary standard and binaries.

How Binary Numbers Work
Binary numbers are actually simpler than decimal numbers as they use only the digits 0 and 1 instead of 0 through 9.

In decimal, when you add 9 and 1, you get 10. But, if you break down the steps, you find that by adding 9 and 1, what you get first is a result of 0 and a carry of 1. The carry of 1 is added to the digits in the next position on the left. In the following example, the carry becomes part of the answer since there are no other digits in that position.


             carry--1
                     9
                  +  1
                  ____
                    10


The following example adds 1 ten times in succession. Note that the binary method has more carries than the decimal method. In binary, 1 and 1 are 0 with a carry of 1.


              Binary      Decimal

                 0           0

              +  1        +  1
              ____        ____
                 1           1

              +  1        +  1
              ____        ____
                10           2

              +  1        +  1
              ____        ____
                11           3

              +  1        +  1
              ____        ____
               100           4

              +  1        +  1
              ____        ____
               101           5

              +  1        +  1
              ____        ____
               110           6

              +  1        +  1
              ____        ____
               111           7

              +  1        +  1
              ____        ____
              1000           8

              +  1        +  1
              ____        ____
              1001           9

              +  1        +  1
              ____        ____
              1010          10





For the True Geek
This Cadence wristwatch shows the numerals 1 to 12 in binary form. It takes four bits to contain all 12 digits. Note that the number 12 has the 4-bit and 8-bit turned on. (Image courtesy of Cadence Watch Company, www.cadencewatch.com)






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