List Of Definitions Paper 1

 List Of Definitions Paper 1

Section 1.1:Components of a Computer System and Modes of Use
#	Term	Definition
1.	Applications Packages	If the software contains programs that allow lots of different tasks to be carried out, together with a book of instructions telling the user how the software should be used.
2.	Generic software	Software that can be used in many different situations to accomplish different things.
3.	Hardware	It is the physical part of the computer system
4.	Input device	It is any piece of hardware that allows data to be transmitted to the computer processor.
5.	Integrated package	It consists of several parts, each of which is an application package. Further, the integrated package is designed so that users can easily move data between the different parts of the integrated package.
6.	Operating system	It is a set of programs, known as system programs, which control the operation of the computer system
7.	Output device	It is any piece of hardware that allows the computer processor to convey information, or the results of its processing
8.	Software	It is the various sets of instructions which tell the system how to do things.
9.	Storage	It is any piece of hardware which can store data outside the processor in a form which is suitable for input back into the processor.
10.	User  interface	It is used to provide a method of communication between the person using the system and the system itself
11.	Utility software	They are system programs designed to carry out common tasks, for instance the programs that control output to the printer or the storage of data.
12.	Applications software	It allows the system to do something useful.
13.	On-line	User has direct contact with processor.
14.	Off-line	User cannot communicate directly with processor.
15.	Disk formatting.	To divide up the surface of a disk into more easily manageable sectors
16.	File handling	To manage the files that are stored on a computer system
17.	Hardware drivers	Used to control communication between computer and peripherals
18.	File compression	Reduces size of files without the loss of any detail
19.	Virus checker	Used to check any files on or entering the system for viruses

Section 1.2: System Software
#	Term	Definition
1.	Batch Processing	It is one that does not allow for interaction between the user and the processor during the execution of the work.
2.	Command line	Set of commands recognised by the operating system e.g. technician has access to whole system
3.	Distributed system	It is one that allows software and data files to be distributed around a system.
4.	Form-based	Prompts operator for inputs e.g. - Operator taking information over phone
5.	GUI	Icons used to stand for options e.g. Non-experienced user
6.	Menu-based	Choices offered to the User which are restricted in number and which lead to further menus.
7.	Multi-access	It is one where it is possible for more than one user to access the system apparently at the same time.
8.	Multi-tasking	A multi-tasking operating system is one where the user of the machine is given the impression that they can carry out more than one task at a time.
9.	Multi-user	It is one that services more than one user simultaneously. There are two types of multi-user O.S.: a network system and a time-sharing system.
10.	Real-time	It is one which can react quickly enough to affect the next input, or process to be carried out.
11.	Single user	It is one that is used to control a system which has only one user, and his programs, at any one time.

Section 1.3: Programming Tools and Techniques
#	Term	Definition
1.	Alpha	Testing is done by the programmer or colleagues in the software house.
2.	Arithmetic error	Inappropriate arithmetic is used, e.g. division by 0 is attempted
3.	Beta	Testing is done by the user/public.
4.	Black-box	Different values (valid, invalid and extreme) can be input for variables to determine whether the program can cope with them.
5.	Logic error	A mistake in the structure of the solution, e.g. a jump goes to the wrong line
6.	Object code	It is the executable form of the program created by the translator
7.	Source code	It is the version of the program written by the programmer in high level language.
8.	Syntax errors	Incorrect use of language, e.g. PLINT instead of PRINT
9.	Top-down	It is an approach to problem in that we started with an original problem (the top) and split the problem into smaller and smaller parts until they became manageable
10.	White box	It is testing the program to determine whether all the possible paths through the program produce the desired results.

Section 1.4: Data: Its Representation, Structure and Management
#	Term	Definition
1.	Archiving	It is taking a copy of little used data for long term storage in case something needed again
2.	ASCII character	A member of the character set that a computer recognizes. It is character on a standard keyboard. It is standard to many machines. It is stored in binary as 7 bit per character.
3.	Backup	It is making a copy of the entire data file in case of corruption of working file.
4.	Boolean data	It is data that can exist in two states, e.g. true or false
5.	character	It can be anything, which is represented in the character set of the computer by a character code in a single byte.
6.	Character set	All the characters that a system can recognize.
7.	Field	Storage space for one data item/one student's name
8.	File	All the data about all the students in the college
9.	fixed length records	The records are of a predetermined size because each field is of a fixed size.
10.	Hashing algorithm	It is pseudo arithmetic that is carried out on the data.
11.	Index Sequential	This method of access involves looking up the first piece of information in an index which narrows the search to a smaller area, having done this, the data is then searched alphabetically in sequence.
12.	Integers	These are whole numbers with which arithmetic can be done.
13.	LIFO	Data enters at one end (of a stack) and leaves at the same end. Hence, 'last in, first out'
14.	Numeric	There are different types of numbers that the computer must be able to recognise.
15.	Random access	It uses the key field as input to a hash algorithm to give a storage location.
16.	Record	All the data about a single student
17.	Sequential	It is a file that holds the data according to some order defined on the data
18.	Serial access	Data is stored in the computer in the order in which it arrives.

Section 1.5: Hardware
#	Term	Definition
1.	ALU	Part of processor where data is processed or manipulated. All I/O must pass through here
2.	Barcode reader	It is a laser scanner that reads the reflected laser light from a series of dark and light coloured lines of varying thickness.
3.	Buffer	It is a small amount of fast memory outside the processor that allows the processor to get on with other work instead of being held up by the secondary device.
4.	Control Unit	To manage the execution of instructions, by running a clock. To decode instructions
5.	Graphics tablet	It is a flat surface on which a piece of paper is placed. The user can then draw on the paper and the tablet will sense where the pencil is pointing and transfer the line to the screen.
6.	Input device	Piece of hardware that allows data to be input to the processor
7.	Interrupt	It is the message which the secondary device can send to the processor which tells the processor that all the data in the buffer has been used up and that it wants some more.
8.	Memory Unit	To store operating system, those parts of applications programs currently running and data currently in use
9.	MICR	This is a device that reads characters that are printed on an original document at the time of it being created. The characters are printed using magnetic ink
10.	OCR	This is a device that reads characters and can distinguish between the different characters in a given character set.
11.	OMR	This device can recognise the presence of a mark on a sheet of paper. The position of the mark conveys information to the machine.
12.	Output device	Piece of hardware that allows the processor to convey the results of its processing.
13.	RAM	It stores the programs that are being used by the computer (including the operating system) and the data that is being used with those programs
14.	ROM	It is memory that cannot be altered. This means that even switching the computer off will not affect the contents of the ROM.
15.	Scanner	It is a device that converts a document into a series of pixels (picture elements – these are small squares that, when put together, form a picture).

Section 1.6: Data Transmission and Networking
#	Term	Definition
1.	Bit rate	It is the number of bits that can be sent in one second.
2.	Bus	In a bus network the hardware items all use the same, central, communication line, known as a bus.
3.	Check sum	Data will normally be sent from one place to another as a block of bytes rather than as individual bytes.
4.	Circuit switching	It involves setting up the route before the message is sent.
5.	Duplex	It is transmission of data over the same link, in both directions, at the same time. E.g. is the use of a telephone.
6.	Echoing Back	The simplest way of checking the transfer of the data is to send it back again.
7.	Half duplex	It is a means of transmitting data in both directions, but only in one direction at a time.  E.g.  a walkie talkie where the handset needs to be set to either send or receive.
8.	LAN	These are networks over small distances.
9.	Network	It is when computers are connected together to share files.
10.	Packet switching	It involves sending the message in segments of equal size, each of which finds its route to the destination.
11.	Parallel	It is the transmission of data more than one bit at a time via many wires.
12.	Parity bit	All data is transmitted as bits (0s and 1s). The Number of 1s in a byte must always be either an odd number or an even number.
13.	Procedure	A small program/subprogram to do a defined task. It is called by a name/identifier.
14.	Protocol	A set of rules to allow communication between devices.
15.	Ring	The workstations are attached to a cable arranged in a ring.
16.	Serial	It is the transmission of data one bit at a time, through one wire
17.	Simplex	It is the transmission of data in only one direction. E.g.is the transmission of a television picture from the transmitter to the receiving aerial, there is no signal sent back.
18.	Star	In a star network the individual pieces of hardware are connected to some central point, usually the network server.
19.	WAN	These are networks over great distances.

Section 1.7: Systems Development Life Cycle
#	Term	Definition
1.	Big bang, or direct change	The old system is removed and the new system replaces it completely and immediately.
2.	Data flow diagram	It shows the way that data enters and leave the system, the storage locations of different data and how the data relates to each other during processing.
3.	Group meeting	This allows a number of people to discuss points and make their views known and yet cuts down on the amount of time spent in interviews getting the same answers over and over again.
4.	Interview	It is particularly important because it allows the interviewee to talk at length, and also to leave a prepared script.
5.	Iterative	The reliance of each stage being on the following stages as well as the previous ones.
6.	Jackson diagram	It shows how the solution can be split into modules using the top down approach and showing the links between modules.
7.	Observation	This is to obtain an exact view of what goes on in present solution.
8.	Parallel running	Until the system can be considered fault free, the old and new systems are run side by side, both doing the same processing.
9.	Phasing	Parts of a system are replaced while the remaining parts are covered by the old system.
10.	Pilot running	Key parts of the new system are run alongside the old system until it is considered that they have been fully tested.
11.	Questionnaire	It makes it possible to find out the views of a large number of people very quickly.
12.	Source documents	This is to collect printed documentation and study it in order to find out what data is required by the system and in what form information is output.
13.	Technical documentation	Used by computer literate person to maintain the system.
14.	User documentation	Explanation of software aimed at person who uses the system.

Section 1.8: Choosing Applications Software
#	Term	Definition
1.	CAD	This is simply the use of a computer system to design a commodity.
2.	CAM	CAM is the use of a computer to help with the manufacturing process.
3.	Custom	It is one that has been specially written to solve a specific problem.
4.	Off-the-shelf	These are pieces of software that have already been written and are immediately available to buy.

#	Term	Definition
Section 1.9: Handling of Data in Information Systems
1.	Automatic data collection	It can be considered to be any data collection that does the two stages of data collection and data input to the system without going through the intermediate phase of data preparation to make it suitable for computer use
2.	Check digit	Extra digit added for example in digits in account number in order to check entry.
3.	Relevance of data	It means that data has a bearing, or use, in that particular application
4.	Timeliness of data	It is the concept that data changes over time and that data is only part of a sensible solution for a short period before it becomes outdated.
5.	Validation	It is a check on data input to the system by comparing the data input with a set of rules that the computer has been told the data must follow.
6.	Verification	It means checking the input data with the original data to make sure that there have been no transcription errors. The standard way to do this is to input the data twice to the computer system.
7.	Video capture card	It is an interface board which fits into one of the expansion slots in a processor that allows the processor to store the values of the screen pixels for a specific picture. In other words it allows the action to be frozen.

Section 1.10: Designing the User Interface
#	Term	Definition
1.	HCI	HCI is the means by which the human and the computer communicate
2.	Speed mismatch	It is the name given to the difference in reaction time of the operator and the computer. The computer is able to take decisions very quickly, while the operator works very slowly

Section 1.11: Characteristics of Information Systems
#	Term	Definition
1.	condition driven	Decisions triggered by meeting some parameter. e.g. Number of a component falls below minimum level
2.	Interactive system	It is one in which data can be entered for processing, which may alter the contents of the database. An example would be the school secretary updating the attendance record of a pupil in the pupil file.
3.	knowledge based system	Expert knowledge covering a small area is brought together in a computer system. It comprises a knowledge base, rule base, inference engine and a HCI
4.	MIS	A management information system is software that allows the managers within a company to access and analyse data.
5.	Passive information systems	These are systems that will answer queries based on the data that is held within them, but the data is not altered. E.g. an electronic encyclopedia
6.	strategic level	Provides information upon which decisions may be based. E.g. One type of product takes longer to produce than another/...

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Answers 1.2

1.      Define what is meant by the term operating system.                             (2)

   A.  -A (suite of) programs…

         -which run the basic functions of the computer/controls the hardware…

         -giving an environment in which to run application software.

         A question which begins with the word define, leaves very little room for manoeuvre because it is asking for a standard answer. This is not an opportunity to show your prowess by making up an answer that is original - there aren’t any. Note, also, the fact that three answers have been given. Always try to give one more answer than seems to be required by the question.

       

  If you look at a mark scheme for an examination paper, the mark points are listed as a set of bullet points so there is no reason why you should not do the same. This style of answer helps you to write down your thoughts easily without getting confused by the language. The purpose of this examination is not to test your ability with English, rather to test your knowledge of computing.

2.      Give two reasons why an operating system is likely to be stored on backing storage rather than in the memory of the computer.                                     (2)

   A.  - A full operating system requires a large amount of storage space that is better utilised in the computer memory for applications

         - Storage of the operating system on backing storage allows for easy upgrading or changing from one system to a different one.

        

Note that the temptation to call the operating system the O.S. has been resisted in the answer. In general, do not use abbreviations in your answers. There are exceptions, where the abbreviation is the accepted form, but your own versions may be ambiguous or, even, not understood by the examiner. If you do need to use an abbreviation, because the term is to be used a number of times, give the term in full with the abbreviation that you want to use in brackets after it. For example, the first time that you use the term operating system write   “…operating system (OS)…” you can then use OS as often as you like in the rest of your answer.

3.      Distinguish between a multi-tasking and a multi-access operating system.       (2)

   A.  - A multi-tasking operating system is one where the user of the machine is given the impression that they can carry out more than one task at a time.

         - A multi-access operating system is one where it is possible for more than one user to access the system apparently at the same time.

         

 Note that there are a large number of points that could have been made about both of these operating systems, but most of them would not answer the question. It is important when answering a question starting with ‘distinguish’ to choose facts that show a comparison.

4.      State what is meant by a distributed system, and give an advantage of this type of multi-access system over a simple network of machines.(2)

   A.  - A distributed system is one which uses many storage locations on different machines to store software and files.

         - Access to files can be speeded up because more than one file command can be carried out at a time.

         When an advantage is asked for it is normal to state in the question, either explicitly or implicitly, with what the comparison should be made. Be careful to give an advantage using this comparison and not a more generalised one.

5.      A computer operator takes phone calls from the public who ring up asking whether a particular item in a catalogue is available. The operator needs to type in a series of responses to questions put to the caller, so that the computer can check the file and determine whether there are any of that item available. Design a screen interface that would be suitable for the operator to use.                                               (4)

   A.  - Form type interface

         -  Catalogue number

         - Space for the description of goods which will be filled in by the computer itself

         - Spaces for computer to produce availability and price

         - Laid out with spaces for input.

        

What is just as important here are the things that would not be on the screen. The question makes it quite clear that there is no ordering going on, so spaces for name and address, or method of payment, are not only going to score no marks, but will probably be penalised because they demonstrate that the candidate has not understood the question. In this type of question it is important to demonstrate that you have taken the situation into account.

6.      The technician responsible for maintaining the system in question 5, uses a command line interface.

         a) Explain what is meant by a command line interface.             (2)

         b) Give two advantages and one disadvantage to the technician of using a command line interface rather than a menu based interface.                         (3)

   A.  a)-Series of commands typed at a screen prompt…

         -which give specific instructions to the computer.

         b)Advantages:

         -Entire system is available to the technician

         -Access to the particular part of the system required is gained more quickly than using other types of interface.

         Disadvantage:

         -The technician needs to know the commands that are available

         -The technician needs to understand the way the system is designed so that it can be navigated efficiently.

        

Note. The language used in this answer is not the sort of language that a candidate will use in an examination. Don’t worry about this. Answers like “so that you can get around the system” are perfectly acceptable.

7.      State three different types of utility software and explain why they are necessary in a computer system.   (6)

    A. - Disk Formatter

         - to divide up the surface of a disk so that the computer can use it.

         - File handling

         - to allow the computer to manage files e.g. storing, and finding them.

         - Hardware driver

         - to give the instructions necessary for using a piece of hardware.

         - File compressor

         - to reduce the size of files so that transmission can be done faster.

         - Virus checker

         - to find and delete viruses on a system before they can damage files.

          

Note. Lots of answers here, but they are all from the syllabus, none are made up because there is no doubt about these whereas there may be doubts if you do not stick to the accepted ones.

         No proprietary brand names are used. Scandisk and Winzip are brand names and will not get the marks.

         Be careful about giving different types – file storage, file sorting and file deletion are all utility programs but they are all file handlers, so would only get one pair of marks.

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Chapter 1.2 System Software

Chapter 1.2 System Software

1.2.(a)         Operating Systems

An operating system is a set of programs designed to run in the background on a computer system, giving an environment in which application software can be executed.

Most operating systems comprise a large set of programs, only some of which are stored in the processor memory all of the time. Many of the routines available in the O.S. are stored on the hard drive so that they can be accessed when required. This not only saves space in the processor memory but also means that the O.S. can be easily changed to a different one.

When you are using an applications package you are not communicating with the computer hardware, you are communicating with the operating system. Without an operating system, no matter how many programs you have, the computer is useless. The operating system sits between the hardware and the application program or user.

1.2.b Types of Operating System

Batch Processing:

When computing was still a new science, there were not enough machines to satisfy the demand for processor time from students in universities who wanted great calculations done, firms who wanted their payroll worked out, and many others. The big problem was the ‘speed mismatch’ between the user sitting at the keyboard who was very slow, and the machine which was very fast. This meant that the expensive part, the computer, was sitting there doing nothing while the human being decided what to do. There are two simple solutions to this problem, one is to buy more machines and the other is to make the machines work more effectively by taking away the slowest part of the system – the human being. Nowadays we might well opt to buy more machines, but this used not to be an option. This problem gave rise to the development of batch processing.

A batch processing operating system is one that does not allow for interaction between the user and the processor during the execution of the work. Lots of programs or data that need to be run are collected together (to form a batch) and they are sent to the computer. The batch operating system then controls their passage through the computer.

Nowadays, batch processing tends to be used where

·         there are large amounts of data to be processed,

·         the data is very similar in nature and…

·         it requires similar processing,

·         the computer system has identifiable times when it is not being used, and so has available processor time

·         the application does not require human intervention.

                                                                                                                                         

 Typical examples of applications which would be done using batch processing include production of bank statements from customer files, production of gas (electricity, telephone) bills from customer records, the compilation of high level language programs where a number of users want programs compiled.

Real-time:

A real-time O.S. is one which can react quickly enough to affect the next input, or process to be carried out. Most real-time systems are based on control of some process in the real world or on information handling. A chemical plant has a reaction vessel where the temperature is critical to the result of the process. The temperature is monitored by a computer which accepts input from a sensor and then makes a decision whether to adjust the heating elements in the vessel. In this example, it would not be sensible for the computer to be running any O.S. that is not real-time because if there was a delay in the decision making process, it might mean that the reaction is corrupted in some way. A robot trolley is controlled by a processor which takes input from a sensor following a black line on the floor, and makes decisions concerning steering to keep the trolley on the black line. If the processor was not controlled by a real-time O.S., the trolley would very soon leave the black line because it would not be steering quickly enough. A catalogue shop processes orders by the  code for a product being input and the system then comparing the code with information in its files. When it finds the correct code it can report to the user the number of that item that there are in the store. If there was only one left of a certain item, it would be necessary to record the fact that a shopper had bought it before the next shopper has their request dealt with otherwise the second person might be sold the same item. Because the information on the system must be processed immediately the O.S. needs to be ready to handle input as soon as it comes in. This means that it cannot be using up some of its slack time doing other tasks while it is waiting to be asked to do something. This implies that the computer will not be using its full potential as far as processing is concerned. When this happens it is said to display a high rate of redundancy. Real-time systems tend to display a high rate of redundancy.

Single User:

As the term implies, a single user O.S. is specifically one that is used to control a system which has only one user, and their programs, at any one time. A perfect example of a single user system is the one that you may have at home. Only one person uses it at a time. Most single user systems are also multi-tasking.

Multi-tasking:

This is a type of O.S. that allows several applications to be available simultaneously. On a simple single user system you will probably be used to having a number of things running at the same time. Perhaps one window shows a spreadsheet while another shows a word processing application. You may decide to copy the sheet from the spreadsheet software to the word-processed document. It appears that more than one task is running simultaneously. They aren’t, they just appear to be. The O.S. that most of us use on our own computer systems, Windows, is a multi-tasking O.S.

Multi-user:

Again, as the name implies, this type of O.S. services more than one user simultaneously. There are two types of multi-user O.S.:

1. A network system comprises a number of computers linked together for the purposes of communication and sharing of resources. Normally one of the machines is used to control the rest of the system, this machine is called the server. Networks are important because they allow hardware and software to be shared and also mean that a single copy of the information on a system is needed, and so can be kept up to date relatively easily.

2. A time-sharing system has a single (normally powerful) computer which is connected up to a number of terminals. These terminals are not computers as in the case of the network system, but have a very limited amount of processing power. Again, such a system allows communication between users on the system and also allows sharing of hardware and software across the system

.

At the moment it is difficult to tell the difference between the two types of multi-user system, but be careful because a network system is not really a multi user system as each computer is only being used by one person at a time. We shall return to this in chapter 3.1

Distributed:

A distributed system is one that allows software and data files to be distributed around a system. An ordinary network will have a server controlling it and the access to the hard drive, which is connected to the server. A distributed system might store the word processing software on one computer’s hard drive, while the files of work are stored somewhere else, and the spreadsheet software is stored on a third disk drive. This can speed access to files because there is no single bottle neck which all the information must pass through, however the security and maintenance of the system are more complicated. Another type of distributed system is to distribute the entire programs and data to more than one place on the network. This speeds up access to the data but means that if data is updated on one part of the system it may not be on others, which means that the different versions of the data need to be compared and amended on a regular basis.

1.2.c  Types of User Interface

A computer is used by a person who needs to communicate with the machine in order to instruct it as to their wishes. The person also receives outputs from the computer. The means of communication between the user and the machine is known as the user interface and consists of both hardware and software. There are different types of interface, which are useful in different situations and for different types of user.

Form based

If the majority of the input to a system is of a standard type, in other words the computer knows what sort of input to expect, then a typical interface will produce a form on the screen to be filled in. This sort of interface would be used where an operator is inputting information while asking a customer questions over the telephone. The interface

·         prompts the operator to ask all the questions

·         makes the operator input the information in the correct order

·         ensures that the information is input in the correct format by having specific areas to input the data

·         makes the checking of the information easier.

The characteristics of a form based interface are that

·         it has specified areas for the data. For example, boxes for input of coded material like the date or the sex of the customer, and areas to be filled in with textual information

·         it has a cursor which moves to the next box to be filled in, sometimes the box is highlighted to make it clear to the operator where the data is to be inserted

·         some of the boxes are more important than others and the cursor will not move on until some data has been supplied

·         it checks that what has been input is sensible for that box before moving on to the next.

Menu based

Menu based interfaces are used in situations where the operator tends not to know what the options are that are available. Examples of this would be information systems for tourists or users of a particular service. A list of choices is made available followed by a further set of choices based on the first choice, and so on until the result is obtained. Imagine a system at a train station in a popular holiday location. The first screen may ask for the general area of interest (accommodation, trips, shopping, entertainment..), once the choice of accommodation has been made the next screen may offer different standards of hotels. The next screen may offer different price bands, and finally a list of all the available properties that match the previous choices.

Input is often done using a touch screen because of the location of such systems and because the people who use them are often in no way computer literate, meaning that simple systems are essential.

Graphical

Graphical interfaces are called GUI (graphical user interface) or WIMP (windows, icons, menus, pointer). The terms describe what the user sees on the screen. There are many different types, but the user would expect to be able to view different applications or files on the screen, this is done by putting each into its own boarded area known as a window. The user will expect to be able to select options by use of menus of choices and by using small pictures which represent the different options available. Choices are selected by the user by using some sort of pointing device to indicate choice, typically this would be a mouse.

Natural language

Sometimes referred to as a conversational interface, the computer will ask questions which elicit a response which gives the user the impression that they are talking to the computer. The trick is that the system restricts itself to questions to which the only sensible answers are the ones that it knows. If the user leaves the expected responses, a message is produced which makes clear that a further attempt is required.

Command line

Or command based interface is one where the user types a series of commands at the keyboard which tell the computer what their intentions are. The user needs to know what the possible commands are, and also needs to understand the way files are stored on the system. The characteristics of a command based interface are

·         the user needs to know what commands are available

·         the user needs to understand the commands

·         the user needs to understand the way that material is stored in the computer system

Because of the above points there are two very important characteristics about a command based interface. First, the system is very much more open than in the other types of interface. Other interfaces restrict the options that the user has available to them. This can be particularly important for the system manager because different users can only be allowed to have access to specific parts of the system. The second characteristic is that command based interfaces can only be used by computer literate people because you not only have to understand the commands and their uses but you also need to understand something about how the computer operates, particular how information is stored.

1.2. (d)        Utility software

Utility programs are part of the operating system of a computer and are routines which carry out important tasks which are necessary from time to time on the system. They do not produce a pretty picture, or a letter which can be sent to someone so they are not application programs, but the types of job that they do are so important that the system could not run without them. There are many examples of utility software but we shall limit ourselves to just a few:

1. The surface of a disk can store so much data that the computer cannot handle it all at once so it needs to be split up so that data stored on it can be found again. When it is new a disk surface is blank so the computer “draws lines” on the surface to split it into small areas. The process is called formatting and it is carried out by a utility program called a disk formatter.

2. When files are to be stored on a disk they need to be managed. This includes arranging for them to be stored in a certain place, finding files again after they have been stored, moving them around to get them in a sensible order and deleting them when they are not needed any more. All of these actions are carried out by utility programs called file handlers.

3. A computer system is made up of lots of different sorts of hardware, each piece of which needs instructions about how to work. These programs are called hardware drivers.

4. Some files are very large. In most files it is possible to find simple ways of reducing the size of the file while keeping all its meaning. This can be very important when files are being sent from one computer to another as the communication is speeded up. The programs that reduce the size of files are called file compressors.

5. When files are being sent from one computer to another it is possible that they may contain a virus which will infect the receiving computer. A virus checker (scanner, killer,..) is a utility program which keeps a constant check on files searching for viruses which it will delete if it finds any.

Example Questions.

1.      Define what is meant by the term operating system.                             (2)

2.      Give two reasons why an operating system is likely to be stored on backing storage rather than in the memory of the computer.                                     (2)

3.      Distinguish between a multi-tasking and a multi-access operating system.       (2)

4.      State what is meant by a distributed system, and give an advantage of this type of multi-access system over a simple network of machines.(2)

5.      A computer operator takes phone calls from the public who ring up asking whether a particular item in a catalogue is available. The operator needs to type in a series of responses to questions put to the caller, so that the computer can check the file and determine whether there are any of that item available. Design a screen interface that would be suitable for the operator to use.                                               (4)

6.      The technician responsible for maintaining the system in question 5, uses a command line interface.

         a) Explain what is meant by a command line interface.             (2)

         b) Give two advantages and one disadvantage to the technician of using a command line interface rather than a menu based interface.           

              (3)

7.      State three different types of utility software and explain why they are necessary in a computer system.                                                                    (6)

ANSWERS

   

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Chapter 1.1 Components of a Computer System and Modes of Use

Chapter 1.1 Components of a Computer System and Modes of Use

1.1 (a and b)                   Hardware and Software Definitions

A computer system consists of hardware and software.

·         An input device is any piece of hardware that allows data to be transmitted to the computer processor. No computer, however powerful, is of value unless it is possible to give it instructions and also data to be used when those instructions are carried out.

·         An output device is any piece of hardware that allows the computer processor to convey information, or the results of its processing. There is no point in having a computer system carrying out processing of any sort unless the results of that processing can be either reported, or used to effect future input to the system.

·         Storage is any piece of hardware which can store data outside the processor in a form which is suitable for input back into the processor. This is necessary because data must be saved for future use if the processor is switched off and for transfer from one machine to another.

The software of a computer system is the various sets of instructions which tell the system how to do things. These sets of instructions are collected together in workable groups known as programs. Without programs of instructions computers would not be able to function because they would not know what to do.

1.1. (c)        Different Software Types

Sets of instructions to make a computer do something are grouped together as programs. These programs make up the software of a computer system.

Depending on the sort of task that a program is expected to accomplish they are grouped into different types of software.

·         Operating system software is a set of programs, known as system programs, which control the operation of the computer system. They are responsible for the way that the pieces of hardware communicate with each other and for monitoring the way that the hardware of the system is used.

·         User interface software is used to provide a method of communication between the person using the system and the system itself. Put very simply it is what you see on the screen when you are using the computer.

·         Translator software is necessary because the computer uses a language that is difficult for human beings to understand and a computer is not capable of understanding human language. The translator software provides the computer with the equivalent of a Chinese-English dictionary so that it can look up what things mean.

·         Utilities, or utility programs, are system programs designed to carry out common tasks, for instance the programs that control output to the printer or the storage of data.

·         Programming languages are used to write sets of instructions that the processor can understand because it has a translator for that language. There are many different programming languages, each of which has been designed to solve a particular type of problem by having commands that are useful for solving the problem.

·         Common applications software includes word processors, graphics, spreadsheets, and many others. These are the programs that you use to produce something worthwhile on the computer. They will be looked at in more detail in chapter 1.8.

Systems Software and Applications Packages

Systems Software

Computers are machines that can carry out operations very quickly. This does not mean that they are in any way intelligent. However fast the machine can work, it is useless if it does not know what to do. Computers need specific instructions for even the most trivial of tasks. If a computer user had to supply these instructions there would be very few people able to use one. Consequently, the manufacturer of the machine will provide programs that are accessible to the user by using very simple commands, these programs are the system software.

·         The operating system is the set of programs that control how the computer responds to user requests. Examples that you may have used include DOS and Windows.

·         Utility programs are additional routines that can be added to an operating system or that are available to the user within an operating system. An example that you may have on your computer system would be a piece of back-up software that can be used to make sure that you do not lose all your work when the computer fails.

·         Some frequently used routines are stored in such a way that they are accessible to users. These routines are stored together in a system library, and form part of the system software. This is something of a grey area between system software and application software because application software also gives access to library areas.

·         Program translators are needed in order to allow users to produce programs in a simple format which can then be translated into something which the computer will understand.

Applications Packages.

A piece of applications software is a program, or set of instructions, designed to make the computer carry out some task. It differs from system software in that it makes the computer do something that is useful for the user. Word word-processing software, or Paintbrush graphics software are both examples of applications software because they both allow the user to produce something that is of general use.

If the software can be used in many different situations to accomplish different things then it is said to be generic software. For example a word processor can be used to write a letter, or to produce a report, or type an essay,… A word processor is a piece of generic software.

If the software contains programs that allow lots of different tasks to be carried out, together with a book of instructions telling the user how the software should be used, then it is called an Applications Package.

An integrated package consists of several parts, each of which is an application package. Further, the integrated package is designed so that users can easily move data between the different parts of the integrated package. For example, if two of the parts are a word-processor and a drawing package, users can move a drawing, created using the drawing package, into the word processing package.

1.1. (d)        Communications Hardware

Computing becomes really powerful when it is possible for different computers to communicate with each other. In order to do this the two computers that are ‘talking’ to each other will need to have a set of rules to keep to otherwise they will not understand each other, there is more about these rules in chapter 1.6. But there is no point in having rules if they are not connected together in some way. The hardware that is used to connect them is known as communications hardware.

Communications hardware can be as simple as a wire going from one computer to another, along which electronic signals can be sent. There are two problems with ‘hardwiring’, the first is that the computers are fixed according to where the wire is and the second is that there is a limit to how far the signal will travel down a wire before degrading and becoming useless.

The first problem can be solved by using radio communication or infra red or any means that does not need a wire.

The second problem can be solved by using a better quality wire to increase the range or by using the telephone lines that are already there. The problem with a telephone line is that it cannot take computer signals, so a special box is needed to change the computer signal to one that can go down the phone line, this box is a piece of communication hardware called a modem.

Whatever the means used to send the signals, the computer has to be able to get the signals ready for sending in the first place, it does this by using a special piece of communications hardware called a network card. The job of the network card is to connect the processor to the wire (or whatever is being used) so that information can be sent and received.

Example Questions.

1.      Explain the difference between hardware and software.                      (2)

2.      Give two reasons why a computer system would need to have some type of external storage device.                                                                                      (2)

3.       Describe the difference between system software and application software.  (2)

4.      An integrated applications package contains a number of different pieces of generic software.

         State what is meant by an integrated applications package and generic software. (3)

one part. In this type of question, some of the marks are always reserved for the last part of the question.

5.      The computers used by two examiners, who live in different cities, need to communicate with each other. State two pieces of hardware that would be necessary to allow the computers to communicate and explain why each is necessary.       (4)

Answers

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Answers 1.1

1.      Explain the difference between hardware and software.                      (2) 

   A.  -Hardware comprises the physical parts of the computer system, while..

         -software are the programs that make the machine produce useful results.

Notice that the answer suggested provides a link between the two terms. This was expected because of the use of the words explain the difference in the question. There are two marks available for the question so make sure that you have said two distinct things. Make sure that the second point is not just the opposite of the first. In this example there would be no mark for saying that software are the other parts that are not physical.

2.      Give two reasons why a computer system would need to have some type of external storage device. 
                                                                                      (2)

   A.  -In order to store files when the power to the processor is switched off.

         -In order to store files which are too large to be stored in the processor itself, until they are needed.

         -To allow for the transfer of data from one machine to another.

         

 Notice that the question asks for reasons why the system needs to have storage, NOT for what is stored. Be careful to answer the question asked. Note that there are two indicators in the question that you should give two answers, the word in bold and the number of marks. This question does not ask for a comparison or an explanation, so don’t give them. Notice that there are more than two acceptable answers. If you can think of three then give them, the examiner will choose the two best, but never give more than one extra answer because you then demonstrate that you are not sure and the examiner will choose your first two answers, right or wrong.

3.       Describe the difference between system software and application software.  (2)

   A.  -System software controls how the computer system works while…

         -application software allows the user to make the computer do something useful.

         Again, this is a comparison type of question so the two parts of the answer should be related.

4.      An integrated applications package contains a number of different pieces of generic software.

         State what is meant by an integrated applications package and generic software. (3)

   A.  An integrated applications package contains

         -a number of different pieces of software which…

         -can communicate with each other in order to…

         -allow the user to produce valuable work.

         -A ‘package’ implies that there will be a user’s guide included.

         Generic software is

         -software that can be used in many areas for different end products.

        

Notice the fact that there are more than three mark points for the first part of the answer, this does not mean that all three marks can be gained by only answering one part. In this type of question, some of the marks are always reserved for the last part of the question.

5.      The computers used by two examiners, who live in different cities, need to communicate with each other. State two pieces of hardware that would be necessary to allow the computers to communicate and explain why each is necessary.       (4)

   A.  -Network card

         -to allow the computer to communicate externally

         -Modem

         -to allow the computers to use the telephone lines for communication/because the computers are a long distance apart.

          

Notice that the question makes it clear that the computers are a long way apart which implies that communication by a hardwire is inappropriate. Realistically, this question would be set after the student has completed the whole of module 1 and will consequently have far more options open to them for the communication medium which will be credited in the exam, but the above answer is all that is expected here. Notice also that any question about communications hardware will automatically give credit for the network card so students should get used to always using it as an example of the hardware.

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