AS LEVEL ICT 2 Processing Different Types of

AS LEVEL ICT 2 Processing Different Types of Information

Types of Data n n n Numbers Text Sound MIDI (Musical Instrument Digital Interface) Bit-mapped graphics Vector graphics

Real Numbers n Numbers with a decimal point are known as real numbers n n The system for holding numbers in this way is not part of the course. Be aware that if ‘numbers’ are to be used in calculations, they have to be held as numbers and not as text.

Internal Data Storage n n Computers work in binary Binary digit (1 or 0) n n Known as as BIT (binary digit) Bits generally grouped together as 8 bits (called a byte) n A byte can hold 28 combinations of 0 s and 1 s n n 256 different characters can be represented. When ‘A’ is pressed, 01000001 is sent to the CPU.

Binary Numbers

Binary Numbers n Convert the following decimal numbers to binary n n 15 30 156 Convert the following numbers from binary to decimal n n n 1010101 1101010110

Binary Addition! 01 10 = 11 n + 01 01 + = 10 Try these for yourself n n n 1+1 10 + 101 110 + 110 11 11 + = 110

ASCII Code American Standard Code for Information Interchange. Char ASCII Character ASCII Char ASCII n space ! " £ $ % & ' ( ) * + , . / 0100000 0100001 0100010 0100011 0100100101 0100110 0100111 0101000 0101001 010101011 0101100 0101101 0101110 0101111 8 9 : ; < = > ? @ A B C D E F G 0111000 0111001 0111010 0111011 0111100 0111101 0111110 0111111 1000000 1000001 1000010 1000011 1000100 1000101 1000110 1000111 P Q R S T U V W X Y Z [ ] ^ _ 1010000 1010001 1010010 1010011 1010100 101010110 1010111 1011000 1011001 1011010 1011011100 1011101 1011110 1011111 h i j k l m n o p q r s t u v w 1101000 1101001 1101010 1101011 1101100 1101101110 1101111 1110000 1110001 1110010 1110011 1110100 1110101 1110110 1110111

Digitised Sound n Input via a microphone n n Sampling rate n n n Converted from analogue to digital by taking a samples How often the card takes a digital snapshot. (higher – more accurate) Measured in k. Hz – CD requires 44 k. Hz (samples per second) Higher sampling rate = Better sound quality

Sampling Rates

Digitised Sound n Sound can be input using a number of devices n n n As with basic telephone line, sound is analogue (wave form) Converted to digital form (i. e. a binary pattern) for storage and processing Hardware – sound card does conversion from analogue to digital and vice versa. n n Resolution – accuracy of measurement of amplitude of sound. 8 -bit board gives 256 (28) sound levels. 16 -bit board gives 65, 536 (216) levels of amplitude. Sound card has built-in synthesiser.

Musical Instrument Digital Interface n MIDI is industry standard applied to: n n n Electronic musical instruments Hardware, cables, connectors & data MIDI interface allows computer to communicate: n Keyboards, drum pads, guitars etc.

Musical Instrument Digital Interface n n MIDI data system stores all information necessary to synthesise musical sounds. Digitally stored data is very compact: n n 30 k for (1 minute of music) Compared with 600 k recorded MIDI files on CDs or diskettes can be loaded and re-played through sound card. Music can be altered because it is stored as instructions.

Bit-Mapped Graphics n Screen is divided into a grid n n Data about each pixel (picture element) is stored n n n Each square is called a pixel (picture element) even if the element contains just white space Bigger the picture, the more pixels are stored thus larger file size Do not scale well - gives jagged edges

Bit-Mapped Graphics n Higher Resolution has more squares n n n Standard used to be 800 x 600 but now 1024 x 768 becoming standard Monochrome only requires 1 bit in memory, (if 1, the pixel is on, if 0 the pixel is off). For colour, each pixel requires 1 byte in memory, giving up to 256 colours for each pixel. Memory is on graphics card – so RAM is not used. The higher the resolution, the sharper the image

Bit-Mapped Graphics n n Collections of pixels Images created by setting colour and other attributes for each pixel The amount of memory required is dependent upon the display adapter Problems: n n May not look correct if transferred to another machine with different adapter or resolution Distortion occurs when you try to enlarge the image

Vector-based (or objectoriented) Graphics n n Graphics represented by recording geometric data NOT graphic data A line defined by is endpoints, length, colour, width, etc n n Used by CAD programs (or special graphics software) to create the line on any screen Line-art of this type said to be deviceindependent

Vector Graphics n n n Can be re-sized without any distortion Creates smaller files Allows for much greater accuracy