The OR operation (occasionally called the inclusive-OR operation to distinguish it more clearly from the exclusive-OR operation which I shall be introducing shortly) combines binary words bit by bit according to the rules:

• 0 OR 0 = 0

• 0 OR 1 = 1

• 1 OR 0 = 1

• 1 OR 1 = 1

In other words, the result is 1 when either bit is 1 or when both bits are 1; alternativel
Author(s): The Open University

My final point in the preceding section brings home the fact that integer arithmetic is not really suitable when divisions are to be performed. It is also not suitable where some or all of the values involved in the arithmetic are not â€“ or are not necessarily â€“ integers, and this is often the case. In such cases, arithmetic has to be performed on non-integers.

The most common representation for non-integers is the floating-point representation that I mentioned briefly in Box 3. You
Author(s): The Open University

Multiplication can be thought of as repeated addition. For instance, in denary arithmetic

7 Ã— 5

can be thought of as

7 + 7 + 7 + 7 + 7

There is therefore no need for a new process for the multiplication of binary integers; multiplication can be transformed into repeated addition.

In multiplication the result is very often much larger than either of the two integers being multiplied, and so a multiple-length representation may be needed to hold the result of a mu
Author(s): The Open University

Personal computers, or PCs, are very versatile computers and can perform a huge range of tasks. So whereas the uses of the kitchen scales and the digital camera indicate clearly what types of data are to be represented, the PC leaves the field very broad indeed. I have therefore chosen to consider some of the data representations used when families and friends use emails to keep in touch. Very conveniently, these lead to some different data representations.

At their simplest, emails are
Author(s): The Open University

CCDs are not inherently able to detect colour, only brightness. So it is necessary to rely on the fact that any colour of light can be made up from the three primary colours of light: red, blue and green. (Note that the three primary colours of light are different from the three primary colours of pigments.) Each CCD in the array is therefore overlaid with a red, blue or green filter and so detects the brightness of, respectively, the red light, the blue light or the green light falling on it
Author(s): The Open University

Just as a denary number system uses ten different digits (0, 1, 2, 3, â€¦ 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 2Â°, which is 1. The ne
Author(s): The Open University

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 course, just as arithmetic (addition, subtraction, etc.) can be performed on everyday denary nu
Author(s): The Open University

A computer is designed to do the following things:

• receive data from the outside world;

• store that data;

• manipulate that data, probably creating and storing more data while doing so;

• present data back to the outside world.

In the next few sections I am going to examine in more detail the data that a computer receives, stores, manipulates and presents. I
Author(s): The Open University

A CD-ROM (Compact Disk Read Only Memory) uses a laser-based optical form of storage. This type of disk has been used for many years to distribute music and computer software. A CD-ROM drive is needed to read the disks. Data is locked into the disk during manufacture, and cannot afterwards be changed.

There are two other types of CD device for computers: CD-R (CD-recordable) and CD-RW (CD-rewritable). With the right sort of CD drive in your computer, you can 'burn' data (that is,
Author(s): The Open University

A stand-alone computer needs two main components to manipulate data: a processor and a working memory.

Author(s): The Open University

A stand-alone computer receives data from a user by means of input devices. The two most commonly used input devices are the keyboard and the mouse. A computer sends data to a user by means of output devices. Data may be output via devices such as a screen or a printer.

There are many different ways of getting data into a computer. For example, a scanner converts images and texts into a format that can be processed by the computer and displayed on screen. Devices such as t
Author(s): The Open University

The network is a communication channel in that it conveys data from the transmitter to the receiver. The network may also manipulate data in some way, and it may also store or retrieve data.

In a mobile phone system, the network conveys the message from User l's handset to User 2's. It will also store the identity of User 1 and the duration of the call. This data is used to work out the amount to charge User 1, which is a form of manipulation of data. A network can be very comple
Author(s): The Open University

The diagram in Figure 6 shows that, for communication to take place, there needs to be some means of conveying the message between the sender and the recipient. I am now going to look at the essential components of 'means of conveying a message'. In other words, I shall treat 'means of conveying a message' as a system and look at
Author(s): The Open University

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## Study another free course

There are more thanÂ 800 coursesÂ on OpenLearnÂ for you to
Author(s): The Open University

Music in UIs is relatively undeveloped, except in games and specialist packages designed for composers and musicians.

Some operating systems have a signature tune that is played automatically when they are loaded. This informs the user that the operating system has loaded correctly and creates a sense of identity, but can be annoying for the user if they have to listen to it repeatedly. A development on this use might be to signpost different parts of the program using musical clips.
Author(s): The Open University

The use of sound is becoming increasingly common, particularly for the following types of application.

• Applications where the eyes and attention are required away from the screen. Relevant examples include flight decks, medical applications, industrial machinery and transport. If you are a runner, you may have a heart rate monitor that allows you to monitor how fast your heart is beating. This is often indicated by an auditory beep, which speeds
Author(s): The Open University

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## Study another free course

There are more thanÂ 800 coursesÂ on OpenLearnÂ for you t
Author(s): The Open University

Liz Bennett and Jon Rosewell

Author(s): The Open University

After studying this course, you should be able to:

• use search engines confidently to locate information and images on the web

• address critically resources that have been located on the web

• describe some of the processes underlying search engines.

Author(s): The Open University

The versatile tiny transistor is now at the heart of the electronics industry. In the video clips you have seen the history of the incredible shrinking chip, its Scottish connections, and an explanation of the physics that make chips work as well as a reconstruction of making a transistor using the crude techniques of yesteryear.

Author(s): The Open University