COUNTING

COUNTING
Computers use the binary system rather than the decimal system. Because computers have only two States: ON or OFF (1 or 0). The binary system is based on 2 while the decimal system is based on 10. Thus, the value to the nearest square of 1000 is 1024 (2 power 10), and will be deemed to be equivalent to 1 KB.
 
For info, it is good to know that some hard drives manufacturers simplify their method of calculation in taking 1000 as the base value. The result is a difference between the advertised capacity of a disk and its actual capacity. Thus, if it does not meet the regulatory calculation method can be changed a 40 GB drive for a 43-GB drive! An unpleasant surprise for the buyer at the time of formatting...
 
Summary:
 
1 kilobytes (K or KB) = 1,024 bytes
1 mega-bytes (MB) = 1 024 K = 1,048,576 bytes
1 gigabyte (GB) = 1024 MB = 1 073 741 824 bytes
1 terabyte (TB) = 1024 GB = 1 199 511 627 776 bytes
 
Examples:
 
12.5 GB = 1,073,741,824 x 12.5 = 13 421 772 800 bytes
545 MB = 545 x 1024 = 080 558 kb
320 MB = 320 x 1,048,576 = 335 544 320 bytes
720 KB = 876 x 1024 = 737 bytes
 
Note: the term "byte" is the English equivalent of the word French 'byte', so if you read for example 25 megabytes (25 MB) this is equivalent to 25 megabytes (25 MB), Ditto for the other measures.
 
The term used for modems is "kilo-bits" that corresponds to the constitution of the bytes. It takes eight bits to define a byte.
 
By simplifying:
 
A modem 56 k so a theoretical not 56 kilobytes but bandwidth of 56 kilobits.
is 56 divided by 8 = 7
In the best of cases, it will obtain a rate less than 7 kilobytes.
 
Note that in the abbreviations:
 
(1) KB = KB = 1024 bytes
(2) Kb = 1024 bytes
 
It said ADSL 512 Kbps: mean 64 KB/s = 512 / 8
 
I would add that after the KB, MB, GB, TO on a Peta bytes (PO)
 
Presentation of the binary
 
size of clusters
 
FAT
 
128 MB = 2 KB
256 MB = 4 KB
512 MB = 8 KB
1024 MB = 16 KB
2048 MB = 32 KB
4096 MB = 64 KB
 
FAT32
 
0.243 has 8 GB = 4 KB
16 GB = 8 KB
32 GB = 16 KB
32 GB = 32 KB
NTFS
1 GB = 1 KB
2 GB = 2 KB
4 GB = 4 KB 8 GB = 8 KB
16 GB = 16 KB
32 GB = 32 KB
32 GB = 64 KB
 
Main units of computing
 
a bit of binary computation
 
From these 2 symbols 0 and 1, the computer can perform all tasks imaginable.
 
The binary equivalent of the decimal digits is written thus:
 
0: 0000
1: 0001
2: 0010
3: 0011
4: 0100
5: 0101
6: 0110
7: 0111
8: 1000
9: 1001
 
To add 2 and 3 in binary, is done according to the same principle as in decimal
 
Note that to multiply a value by 2, it simply offset binary digits of a row to the left and add a 0.
 
 
So double 0011 is 0110
 
This type of operation is done very easily by a computer
 
further explanation on the binary
 
A binary byte to decimal conversion
 
A byte consists of 8 bits. It can take a value between 0 and 256
 
example: the 11100110 byte is the number 230
 
The principle of binary to decimal conversion is carried out as follows:
 
either the number:
 
1 1 1 0 0 1 1 0
 
from left, each bit corresponds to the rank of an output power of 2
 
27 26 25 24 23 22 21 20
 
multiply the value of each bit by the power of the same rank 2
 
in the case of our number:
 
Programmers also use hexadecimal notation which corresponds to the base-16, by convention each digit is encoded as:
 
0 1 2 3 4 5 6 7 8 9
 
A B C D E F
 
(F is 15 in decimal)
 
A byte is written using 2 hexadecimal symbols
 
by separating the 8 bits in 2 groups of 4 bits

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Last edited: 2012-11-03

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