AS LEVEL ICT2 Processing Different Types of Information

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

Real Numbers Numbers with a decimal point are known as real numbers 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 Computers work in binary Binary digit (1 or 0) Known as as BIT (binary digit) Bits generally grouped together as 8 bits (called a byte) A byte can hold 2 8 combinations of 0s and 1s 256 different characters can be represented. When ‘A’ is pressed, is sent to the CPU.

Binary Numbers

Convert the following decimal numbers to binary Convert the following numbers from binary to decimal

Binary Addition! = 11 = 10 = 110 Try these for yourself

ASCII Code American Standard Code for Information Interchange Character ASCII Char ASCII Char ASCII Char ASCII space P h ! Q i " : R j £ ; S k $ < T l % = U m & > V n ' ? W o ) A Y q * B Z r C [ s , D \ t E ] u F ^ v / G _ w

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

Sampling Rates

Digitised Sound Sound can be input using a number of devices 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. Resolution – accuracy of measurement of amplitude of sound. 8-bit board gives 256 (2 8 ) sound levels. 16-bit board gives 65,536 (2 16 ) levels of amplitude. Sound card has built-in synthesiser.

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

Musical Instrument Digital Interface MIDI data system stores all information necessary to synthesise musical sounds. Digitally stored data is very compact: 30k for (1 minute of music) Compared with 600k 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 Screen is divided into a grid Each square is called a pixel (picture element) Data about each pixel (picture element) is stored 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 Higher Resolution has more squares Standard used to be 800x600 but now 1024x768 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 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: 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 object- oriented) Graphics Graphics represented by recording geometric data NOT graphic data A line defined by is endpoints, length, colour, width, etc Used by CAD programs (or special graphics software) to create the line on any screen Line-art of this type said to be device- independent

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