Data-representation-计算机系统概论(双语)专业英语课件.ppt

Data representationInformation theoryThe study of the most efficient way to represent or encode information is called information theoryThe way in which information is encoded and stored in a computer is referred to as.Representing informationA computer uses a bit as the building block for more complex messages,which are constructed with a series of bits.With one bit we can convey two unit of informationWith two bit you can convey four unit of informationRepresenting numbersWe can represent numbers in the following two ways.Binary system decimal systemThe binary equivalent of the no 5 is 101ASCII(American Standard Code for information interchange)EBCDIC Representing graphics and videoPg No:451.There are two different approaches to encoding graphics for computer system.BitmapVectorBitmap graphicsComputers store bitmap images,such as digital photos using a code that indicates the state of each individual dot,or pixel displayed on the screen.The simplest bitmap image is a Monochrome which contains only the colors white and black.Vector graphicsA Vector graphic consists of a set of instructions that recreates a picture.When you create vector graphic you draw line and shape in various colors.The computer then translates these lines and shapes into a set of instructions that can recreate your graphic.Vector graphic files typically have extensions such as.wmf,.dxf,.mgx,.eps and.cgmRepresenting sound Sound or audio data can be represented in two different ways.As a waveformAs a MIDI musicMIDI files have the following extensions.mid,.cmf,.rol