Cg3 - Computing

A web log is a set of entries / diary on the world wide web (which is accessible to any web user.)

A data structure is a group of related data items

A data structure which is a set of data elements of the same type

A Record is a set of data items all related to a single entity

A router is a device in a network which holds information about the addresses of computers in the network

A Sequential file is a where records are stored in key sequence order

An indexed sequential file allows serial access to the records but also access directly via the index, (which will be much quicker).

Files are often encrypted to safeguard the data

The person’s voice needs to have been recorded previously and it needs to be compare with the original

An area of memory used to store data that is in transit between two locations, e.g. moving data between a digital camera and a printer

Whilst one buffer is being emptied, another can be filled

Quicker, avoids waiting for the data transfer

In a printer queue/ video stream

Multitasking occurs when more than one task or application is available to the user at the same time

- Run time error

- Input/Output request

- Software fault

- Keyboard button clicked

- Printer run out of paper

- Hardware fault

- Check correspondence between the actual design and its specification

- Confirm the most appropriate techniques have been carried out

- Confirm HCI is appropriate

A primary key (is a field which) uniquely identifies a record in a database.

A foreign key is a primary key from one table, included in another table to form a link

• improve (read) access times for records

• sort the records (for viewing/output)

Databases often contain huge amounts of data, It is often more efficient to store data on a number of different computers in different locations to maximize performance.

Both processing and data

- Structured English

- Flowcharts

- Pseudo code

A parameter is a variable that can be passed to / from the procedure

ByVal (By Value)

ByRef (By Reference)

BNF is used to describe (unambiguously) the syntax of a computer language

Relocatable code is program code which can be moved by the operating system from one area of computer memory to another.

Subprogram libraries contain (well-tested) common tasks, etc and can be used by any user, avoiding re-writing.

A link loader is a software tool which combines already compiled modules into the executable program.

link editor cannot find a compiled module

- A printer queue

- A keyboard buffer

- A download buffer

- A processor scheduling queue

Occurs when the number is too close to zero to bestored by the computer

Occurs when the number is too large to be stored by thecomputer

Archiving is the process of storing data which is no longer in current use. For example data stored for legal reasons

The process is not running because it is waiting for some event(such as an input/output operation)

The process is not running because another process is currentlybeing run / waiting for processor time

Any partial dependencies must be removed

A pass is made through the data, comparing each value with the following one and swapping them if necessary. A number of passes is made until the data is in order / no swaps

A recursive algorithm is one which calls itself

It must also have a terminating condition

A scripting language ( is often embedded in other languages and) can addfunctionality to web pages

Used in a relational database system as a query / manipulation language

because it is relatively close to natural language so requires less programming skill

Used for production of GUI

because it may be more intuitive because visual tools are available

Used for simulation/control applications

because it may have special features relevant to the application e.g. time analysis elements

Subprogram return addresses e.g. undo / back

Protocols are necessary to specify data formats, etc, to enable devices to communicate with each other

Data sent bit-by-bit along the same data line

All bits in a byte are sent simultaneously along separate data lines

Because many input devices (eg microphone, sensor producing continuously varying voltage etc) produce an analogue signal

faster to search/add a value

more complex to program / process

Computer prompts for input into specific fields on a screen dialogue form

A method of benefitting from the speed of a CPU compared with slower peripherals

Any transitive dependencies need to be removed to convert from 2NF to 3NF

It needs to be ensured that each attribute depends only on the primary key

Converts a low level program to machine code

An interpreter translates each line of the source program then executes it

A compiler translates the whole source code / program prior to execution

Allows very fast access irrespective of position in file – very suitable for large files which need this sort of access

Easier to program

Allows faster access than sequential because can move directly to individual records

The internet is a publicly accessible, international collection of interconnected networks

Collection of webpages held locally on the server of a organisation such as a company or a college

Like internet, except it is accessible to certain individuals who are not member of the organisation, such as customers

All digits are moved to the left. The left-most digit is discarded and the new right-most digit becomes a zero.

All digits are moved to the right. The right-most digit is discarded and the new left-most digit becomes a zero.

All digits are moved to the left. The right-most digit becomes a zero and the left-most bit is discarded. This operation can result in overflow, if the left-most bit has changed from a 1 to a 0 or vice-versa. This operation can be used for dividing by two.

All digits are moved to the right except for the left-most bit. The right-most bit is discarded, while the left-most bit remains as it was. This has the effect of making sure that negative numbers remain negative numbers. This operation can be used for multiplying by two.

Source code generation, Data modelling, Refactoring, UML generation

The main aim of CASE tools is the elimination of the need for a programmer to create and fine-tune every individual line of code

To aid in the development of the way in which data moves around the system and is stored

Refactoring is changing the code of a program without changing its function. This might be to make code more readable, more maintainable or quicker in execution.