FEW BASIC CONCEPTS

FEW BASIC CONCEPTS DEFINITION

                               

Bit 

The smallest piece of information used by the computer. Derived from "binary digit".   In computer language, either a one (1) or a zero (0).

Backup 

A copy of a file or disk you make for archiving purposes.

Bus 

An electronic pathway through which data is transmitted between components in a computer.

Byte 

A piece of computer information made up of eight bits.

Copy / Paste 

Is the process of selecting text, pictures or files and the copying the selection to the clipboard (temporary storage area). The information is then pasted into the new location such as a different directory for files or a different section of a document for text.

Browser 

A browser is used to surf the Internet. The most popular or well known browser is Internet Explorer but there are Chrome, Firefox and Opera also. A browser is used to display web pages and web sites from the Internet.

Directory 

A directory is a location where you store your files. There are a default set of directories that are created when the computer is setup and when software is installed. To make the saving and retrieval of files easier by creating you own directories (or directory structure) to store the files that you create. 

Web Page 

A web page is a single page of information that is located on the on the Internet. The page may display text, pictures or be interactive such a game.

Web Site 

A web site is a collection of web pages that all relate to each other. For example,  google.com is a web site and the PC Advice Home Page is a web page that is part of the site.

BIT

     A bit is the smallest unit of information that can be stored or manipulated on a computer.

          

       It consists of either zero or one. Depending on meaning, implication, or even style, it could instead be described as false/true, off/on, no/yes, and so on. We can also call a bit a binary digit, especially when working with the 0 or 1 values.

                                   

                         

BYTE

    Although computers usually provide instructions that can test and manipulate bits, they generally are designed to store data and execute instructions in bit multiples called bytes. In most computer systems, there are eight bits in a byte. The value of a bit is usually stored as either above or below a designated level of electrical charge in a single capacitor within a memory device.

          A byte also happens to be how many bits are needed to represent letters of the alphabet and other characters. For example, the letter "A" would be 01000001; my initials "KJW" would be010010110100101001010111. To make this a little bit easier to see where the bytes are it is customary place a comma every four digits, to make what are sometimes called nibbles:0100,1011,0100,1010,0101,0111. That's not really much easier for people to read or write--and many computer engineers, programmers, and analysts need to read and write even longer binary codes than this.

It so happens that there are only 16 different ways to write 0's and 1's four times. So something called hexademical code can be used to make the numbers shorter by translating each nibble (or half-a-byte) like this:

Binary:	0000	0001	0010	0011	0100	0101	0110	0111	1000	1001	1010	1011	1100	1101	1110	1111
Hexademical:	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F

Nibble

Half a byte (four bits) is called a nibble.

Units of Data Measurement

                                   

  DIFFERENCE BETWEEN BIT AND BYTES

The terms "bits" and "bytes" are often confused and are even used interchangeably since they sound similar and are both abbreviated with the letter "B." However, when written correctly, bits are abbreviated with a lowercase "b," while bytes are abbreviated with a capital "B." It is important not to confuse these two terms, since any measurement in bytes contains eight times as many bits. For example a small textfile that is 4 KB in size contains 4,000 bytes, or 32,000 bits.

Generally, files, storage devices, and storage capacity are measured in bytes, while data transfer rates are measured in bits. For instance, an SSD may have a storage capacity of 240 GB, while a download may transfer at 10 Mbps. Additionally, bits are also used to describe processor architecture, such as a 32-bit or 64-bit processor.

     For example in Internet Protocol (IP) networking, IP addresses contain 32 bits or 4 bytes. The bits encode the network address so that it can be shared on the network. The bytes divide the bits into groups.

The IP address 192.168.0.1, for instance, is encoded with the following bits and bytes:

11000000 10101000 00000000 00000001.

    Bits are grouped into bytes to, generally speaking, increase the efficiency of computer hardware,including network equipment, disks and memory.

 REFRENCES

http://computer.howstuffworks.com/bytes1.htm

http://en.wikipedia.org/wiki/Bit

http://techterms.com/definition/bit

Checksum

CHECKSUM

        A simple error-detection scheme in which each transmitted message is accompanied by a numerical value based on the number of set bits in the message.

1. A checksum or hash sum is a small-size datum from an arbitrary block of digital data for the purpose of detecting errors which may have been introduced during its transmission or storage. It is usually applied to an installation file after it is received from the download server.

   A checksum or hash sum is a small-size datum from an arbitrary block of digital data for the purpose of detecting errors which may have been introduced during its transmission or storage.  (According toWikipedia)

   The actual procedure which yields the checksum, given a data input is called a checksum function or checksum algorithm.

   

    

   
   

INTERNET PROTOCOL

              Internet Protocol or IP is the primary network protocol used on the Internet, developed in 1970s. On the Internet and many other networks, IP is often used together with the Transport Control Protocol (TCP) and referred to interchangeably as TCP/IP.

    Data on an IP network is organized into packets. EacH IP PACKET includes both a header (that specifies source, destination, and other information about the data) and the message data itself.IP functions at layer 3 of the OSI model. 

                                                 

IP Address: 

       A logical numeric address that is assigned to every single computer, printer, switch, router or any other device that is part of a TCP/IP-based network

Pv4 Addressing Notation

          An IPv4 address consists of four bytes (32 bits). These bytes are also known as octets.

For readability purposes, humans typically work with IP addresses in a notation called dotted decimal. This notation places periods between each of the four numbers (octets) that comprise an IP address. For example, an IP address that computers see as

• 00001010 00000000 00000000 00000001

  is written in dotted decimal as

• 10.0.0.1

         Because each byte contains 8 bits, each octet in an IP address ranges in value from a minimum of 0 to a maximum of 255. Therefore, the full range of IP addresses is from0.0.0.0 through 255.255.255.255 

. This represents a total of 4,294,967,296 possible IP addresses.

IPv6 Addressing Notation

      IP addresses change significantly with IPv6. IPv6 addresses are 16 bytes (128 bits) long rather than four bytes (32 bits). This larger size means that IPv6 supports more than

• 300,000,000,000,000,000,000,000,000,000,000,000,000

possible addresses! As an increasing number of cell phones and other consumer electronics expand their networking capability and require their own addresses, the smaller IPv4 address space will eventually run out and IPv6 become mandatory.

IPv6 addresses are generally written in the following form:

• hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh

In this full notation, pairs of IPv6 bytes are separated by a colon and each byte in turns is represented as a pair of hexadecimal numbers, like in the following example:

• E3D7:0000:0000:0000:51F4:9BC8:C0A8:6420

      As shown above, IPv6 addresses commonly contain many bytes with a zero value.Shorthand notation in IPv6 removes these values from the text representation (though the bytes are still present in the actual network address) as follows:

• E3D7::51F4:9BC8:C0A8:6420

              Finally, many IPv6 addresses are extensions of IPv4 addresses. In these cases, the rightmost four bytes of an IPv6 address (the rightmost two byte pairs) may be rewritten in the IPv4 notation. Converting the above example to mixed notation yields

• E3D7::51F4:9BC8:192.168.100.32