2.2.2 Positive integers: binary numbers Just as a denary number system uses ten different digits (0, 1, 2, 3, … 9), a binary number system uses two (0, 1). Once again the idea of positional notation is important. You have just seen that the weightings which apply to the digits in a denary number are the exponents of ten. With binary numbers, where only two digits are used, the weightings applied to the digits are exponents of two. The rightmost bit is given the weighting of 2°, which is 1. The ne
2.2.1 Positive integers: denary numbers The number system which we all use in everyday life is called the denary representation, or sometimes the decimal representation, of numbers. In this system, the ten digits 0 to 9 are used, either singly or in ordered groups. The important point for you to grasp is that when the digits are used in ordered groups, each digit is understood to have a weighting. For example, consider the denary number 549. Here 5 has the weighting of hundreds, 4 has the weighting of tens and
2.2 Representing numbers: positive integers A very straightforward way of finding binary codes to represent positive integers is simply to use the binary number that corresponds to each integer. This is because every positive integer in the everyday number system (known as the decimal or denary system because it uses 10 different digits) has a corresponding number in the binary number system. As you will see later, in Section 7 of this unit, just as arithmetic (addition, subtraction, etc.) can be performed on everyday denary numb
16.2.1 Receiving data In a supermarket ICT system, there needs to be some way for the computer to receive information about the items a customer is buying. Think back to a recent visit to your local supermarket and how you ma 4.2.3 Second computer (the FirstClass server) The computer on the right of Figure 11 receives the data, manipulates it and then stores it. The computer then typically sends some kind of response back via the network, which may require the computer to retrieve some stored data. The computer in this example is one of the Ope 14.1 Introduction Now that I have introduced you to the processes carried out by a stand-alone computer, I will move on to discuss what happens when computers are linked. 12.2 Bytes of data You will recall from Section 6.2 that a binary digit, or bit, can have one of two values: either a 0 or a 1. In a computer, bits are assembled into groups of eight, and a group of eight bits is known as a byte. The abbreviation used for a byte is B, so 512 bytes would be written as 512 B. Although this course will use ‘b’ for bit and ‘B’ for byte, you should be aware that not everyone makes this clear distinction. A byte of data can represent many different things in a co 11.2 The processor The processor can be thought of as the ‘brain’ of the computer in that it manages everything the computer does. A processor is contained on a single microchip or ‘chip’. A chip is a small, thin slice of silicon, which might measure only a centimetre across but can contain hundreds of millions of transistors. The transistors are joined together into circuits by tiny wires which can be more than a hundred times thinner than a human hair. These tiny circuits enable t 9 A stand-alone computer The computer you are using for your studies is called a personal computer or PC. Although you have an internet connection for use in this course, your computer can probably also be used as a stand-alone computer. Your PC may be a desktop computer or a notebook computer (sometimes known as a laptop computer). Usually a desktop computer comes with separate devices such as a monitor, a keyboard, a mouse and speakers and it runs on mains electricity. Notebook computers 4.1.3 The receiver The receiver receives data from the network and manipulates it into a message to send to User 2. Sometimes the receiver may also store or retrieve data. In the mobile phone communication system, the data received from the network must be manipulated back into sound before being sent to the user. In addition, some mobile phones can store and retrieve data about the user's contacts, so that when a call is received they can translate the phone number of the caller into a name which is then 3.1 Introduction Generally, when we talk about communication between humans, we mean one person conveying information to another person. Figure 6 shows a basic model, or representation, of a communication system for getting a message from the sender to the recipient. The diagram shows the sender (User 2.2.2 Drawing the boundary Deciding where to place the system boundary is an important consideration in that we have to think about what to include and exclude. This isn't always an easy decision to make and it often depends on the perspective of the person viewing the system. The system maps in Figures 1 2.2.1 Subsystems An important aspect of systems is that each component can be considered as a subsystem. In the health centre appointments system, the ‘computerised booking system’ may be a complex system in its own right involving a number of computers networked together. Figure 2 shows Introduction This unit is from our archive and it is an adapted extract from Networked living: exploring information and communication technologies
(T175) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this curriculum area. This unit will introduce you to some ideas about how information and 3.6 Viewing the data Reverting to the relational database we constructed in Section 3.3, you might wonder what, from the user's point of view, has been gained by creating separate tables for the students and courses. With Table 1 you could see at a glance who was studying what. In the relational database it was har 3.5 Other kinds of data All the data we have had so far in the database has been text or numbers. I have mentioned that another type of data might be dates. Modern databases, however, can store other kinds of data than text, numbers and dates. They can also store graphics, moving pictures and sounds. 1 E-government In many countries, e-government has become part of government policy. The UK government has a large e-government project under way, as do the governments of the USA, Australia and Japan, to name just a few. The ‘e’ at the start of ‘e-government’ stands for ‘electronic’, and e-government usually refers to the use by governments of ICTs. In many ways e-government is not a single activity but many activities. However, in the UK and many other countries, there is a degree of central c Introduction This unit is from our archive and it is an adapted extract from Networked living: exploring information and communication technologies (T175) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this curriculum area. Many governments across the world are moving towards the use of infor 1.6.2 Different types of sound Sounds come in four categories.
Sound effects. Many UIs contain a range of warning beeps and reassuring sounds confirming that operations have been completed. These can include naturalistic sounds, such as the sound of a piece of screwed-up paper dropping into a waste paper basket.
Music. Many composers use computer systems to compose music, and programs such as games make extensive use of music. Short sequences of mus 1.3.4 How to use colour to good effect The effective use of colour is a complex and technical area. In Table 2 we have listed some general guidelines.
Activity 13 (exploratory)
Activity 12 (exploratory)
Table 2: Making e
