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
Author(s): The Open University

I'm going to pause here to try to put together some of the ideas we have encountered so far. I deliberately chose the example of a supermarket to illustrate some of the key processes involved in an ICT system. Figure 15 is a modified version of the block diagram for computers in a ne
Author(s): The Open University

In a supermarket ICT system, there needs to be some way for the computer to receive information about the items a customer is buying.

## Activity 13 (exploratory)

Think back to a recent visit to your local supermarket and how you ma
Author(s): The Open University

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
Author(s): The Open University

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.

Author(s): The Open University

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 â€˜bâ€™ for bit and â€˜Bâ€™ 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
Author(s): The Open University

The processor can be thought of as the â€˜brainâ€™ of the computer in that it manages everything the computer does. A processor is contained on a single microchip or â€˜chipâ€™. 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
Author(s): The Open University

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
Author(s): The Open University

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
Author(s): The Open University

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
Author(s): The Open University

An important aspect of systems is that each component can be considered as a subsystem. In the health centre appointments system, the â€˜computerised booking systemâ€™ may be a complex system in its own right involving a number of computers networked together. Figure 2 shows
Author(s): The Open University

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
Author(s): The Open University

A hacker who threatens your organisation's information assets is taking advantage of vulnerabilities in the media and systems which handle them. Vulnerabilities and threats clearly go hand-in-hand: each threat is directed at a vulnerability.

The relationship between information assets, threats, vulnerabilities and existing defences is illustrated in Author(s): The Open University

Section 5 discussed the ISMS planning and documentation process in general and also went into the details of Stages 1, 2 and 8 of the ISMS documentation task. In this section, we shall discuss Stage 3 of the ISMS documentation task and see how to define a systematic approach to risk assessment. We shall also look at the asset identification task. The remaining two tasks, risk assessment and risk treatment, are outside the scope of this unit.

Author(s): The Open University

Start Internet Explorer.

Choose Tools > Windows update from the drop-down menu at the top of the browser screen.

(Note: if you are using a computer at work that is controlled by an IT group this option may be missing, as it can be disabled in a corporate environment.)

If you are unable to find the â€˜updateâ€™ option, you could try the Microsoft update site.

Follow the on-screen option to scan your computer and see the number of updates that are available to you.

Author(s): The Open University

Microsoft Windows is an example of an operating system (OS). These operating systems contain millions of lines of code, and inevitably there will be some errors in that code. Some malware writers set out to find these errors, or holes, in the code and exploit them to their own benefit. Whenever holes are found (by IT security people or groups, malware writers or the software developer) the operating system manufacturer will issue a fix for the particular problem. These fixes are referred to a
Author(s): The Open University

The figures below show how the problem of malware has increased over the last 30 years.

1974First self-replicating code (Xerox)
1982First virus on the Apple platform
1984First conference papers on viruses presented
1986First recorded virus infection on the PC
19
Author(s): The Open University

An alternative to using general purpose search engines is to make use of focused search engines that only index known genealogical sites. For example, the Genealogical Society of the UK and Ireland (GenUKI) provides a search engine.

## Activity 24

Author(s): The Open University

In this section we consider searching for information about your ancestors. We cannot hope to cover all the techniques and information required to research genealogy, family history and local history; there is only time in this unit to scratch the surface. Some of the activities here are open-ended; please do not spend too long on them. If the subject interests you, you can revisit it after the course finishes, making use of the genealogical resources in the Appendix.

Author(s): The Open University

## Activity 30: exploratory

Read the extracts below. Using the information they contain, make notes about the main differences between active and passive RFID tags. You will get more out of this exercise if you make a serious attempt to d
Author(s): The Open University