Uses of Hexadecimal System • • • • • blue screen of death (BSOD) Media Access Control • Uniquely identifies a device on a network • Not a single device in this world connected to internet has same MAC addresses • Rarely Changed • Usually 48 bits divided into 6 groups • NN-NN-NN-DD-DD-DD where NN on left side represents Manufacturer And DD on right side represents serial number of device. • There are two types of MAC • LAA and UAA • LAA = Locally Administered MAC Address • UAA = Universally Administered MAC Address • UAA is most common set by manufacturer. User cannot change this address. • There are some occasions when user wishes to change MAC address and uses LAA mac addresses. • Certain software used on mainframe system need strict format MAC addresses • To limit bypass of MAC address filter on a router/firewall. IP addresses • • • • • Known as Internet Protocol Every device connected to a network has an IP address Devices connected to same router can have same ip addresses IPV4 = IP version 4 .Old version.32 bit number . Example 109.108.158.1 IPV6 = IP version 6 . Updated version.128 bit number broken into 16 bit groups uses hexadecimal number system. Example 2001:0db8:85a3:0000:0000:8a2e:0370:7334. • IPV6 uses colon ( : ) instead of decimal point ( . ) as used in IPV4 HTML Color Codes • HTML is used to develop WEB pages • HTML uses <tags> example <h1> and </h1> • HTML often uses hexadecimal numbers to represent colors • Example #FF 00 00 for red • # 00 FF 00 for green • • The # symbol always precedes hexadecimal value in HTML code. There are 256 values for red,256 values for green and 256 values for blue components. • 256*256*256 = 16 777 216 possible colors Text Representation • Two Character Sets • ASCII 7-Bit (Standard)..1963 • Includes 0 to 127 codes in denary • Includes 00 to 7F codes in hexadecimal • ASCII is a 7-bit code, meaning that 128 characters (27) are defined. The code consists of 33 nonprintable and 95 printable characters and includes both letters, punctuation marks, numbers, and control characters. • Does not represent character in non-western language example Chinese,Japanese • ASCII 8-Bit (Extended)..1986 • Includes 0 to 255 codes in denary • Includes 0 to FF in hexadecimal • Includes some non-English and graphical characters • Does not represent character in non-western language example Chinese,Japanese Text Representation • Unicode • Represents all languages of the world. Was set up in 1991 • Supports many operating systems • Supports up to 4 bytes per character- 16 to 32 bits to represent same character Sound Representation • Sound needs to be converted into binary for computers to be able to process it. To do this, sound is captured - usually by a microphone - and then converted into a digital signal. • An analogue to digital converter will sample a sound wave at regular time intervals. For example, a sound wave like this can be sampled at each time sample point: Sound Representation This means that the sound loses quality as data has been lost between the time samples. The frequency at which samples are taken is called the sample rate, and is measured in Hertz (Hz). 1 Hz is one sample per second. Most CD-quality audio is sampled at 44 100 Sound Representation Sample resolution also known as Bit Depth (the number of bits per sample) determines how many gradations of amplitude (corresponding to loudness) can be represented in the digital waveform. Sample rate / Sampling is the number of samples of a sound that are taken per second to represent the event How Sampling is used to record Sound • The amplitude of sound is determined at set time intervals • Approximate sound wave is represented • Each sample of sound is then encoded in binary values Note High Sample rate or larger resolution = high quality sound and greater file size Images Representation • Bitmap Images are made up of Pixels (Picture Elements) • Each Pixel can be represented as a binary number • Black and white image requires 1 Bit per pixel • 2 bit colors means 22 = 4 colors • 32 bit colors means 2 32 = 4294967296 colors • The number of bits used to represent each color is called Color Depth • Increasing color depth ,increases file size • Image resolution refers to as number of pixels that make up an image • HD image may have 4096 by 3072 pixels • Increase in resolution means increase in file size Calculation of file size Images Image Resolution (In Pixels) X Color Depth (in bits) Or Height (In Pixels) X Width (In Pixels) X Color Depth (in bits) Calculation of file size Sound Sample Rate (in Hz) X Sample Resolution (in bits) X Length (in Seconds) X Channels (either 2 or 1) Note : Channels Stereo : Means Audio channels having 2 audio signals Mono:Means Audio channel having 1 audio signal Compression Why Compression is required ? To save storage space To reduce time taken to stream a music or video file To reduce time taken to upload ,download or transfer a file thus making less use of network bandwidth. To reduce costs.(ISP costs , Cloud Storage Costs) Compression Lossy Eliminates unnecessary /unwanted data from file permanently In case of sound Reduce sampling rate Reduce in bit depth In case of image Reduce in resolution Reduce in color depth MP3 MP4 JPEG Compression 1 1 1 1 1 Lossless 3z 2 o Compressed data can be reconstructed Designed so that no data is lost RLE Lossless Compression • • • • Run-Length Encoding Lossless compression for text and image files Reduces size of string of adjacent , identical data Repeating string is encoded into Two values • • • First value represents number of identical data items Second value represents the code of data item RLE is only effective when there is long run of repeated units 0 0 Compression RLE on TEXT Compression RLE on B/W image RLE on Color Image b) An encryption key was calculated by performing right logical shift 0 0 1 0 What will be the new number. c) After logical shift new value of this number into hexa decimal number. is transmitted along with encryption key. Convert 0 0 1 0
