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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