CG1

Operating System Tasks (Managing Peripherals)

- Communicates with and sends data output to a printer/monitor/other valid output device - Communicates with and receives data input to a keyboard/mouse/other valid input device

Operating System Tasks (Spooling)

- Data is stored on hard disc/in memory/stored in a queue - Document is printed when printer is free/in correct order - Benefit of spooling - User can carry on working/log off when waiting for job to print

Operating System Tasks (Manages Memory)

- Ensures programs/data do not corrupt each other - Ensures all programs and data including itself is stored in correct memory locations

Operating System Tasks (Manage Processes)

-Ensures different processes can utilise the CPU and do not interfere with each other or crash -On a multi-tasking O/S ensure that all tasks appear to run simultaneously

Binary Search

A binary search is a much quicker algorithm which only works if data is sorted. Rather than starting the search at one end of the data structure, a binary search begins in the middle.

Bus

A bus is a number of wires used to connect computer components together to enable communication.

Serial Bus

A bus that consists of one wire

Byte

A collection of eight consecutive bits such as 01101110.

Record

A collection of items all relating to an object and is treated as a unit for processing

Intranet

A collection of web pages held locally on the server of an organisation such as a company or a college. These typically contain information that should not be made publicly accessible, as intranets are only available to members of an organisation (employees, students, etc.) who have authorisation to access them and login details.

Lossless Compression

A compression method in which no data is lost. With this type of compression, a large file can be compressed to take up less space and then uncompressed without any loss of information.

Entity Diagram

A data modelling technique that can help define business processes and can be used as the foundation for a relational database.

Secondary Storage

A device that can store data, in addition to main memory. Secondary storage devices are non-volatile and are typically high capacity, portable or both.

Check Digit

A digit in a numerical field, such as an account number, that is generated by performing a calculation of the other digits. The operator does not need to know which digit is the check digit; an error would appear on screen if the check digit was inconsistent, because this would mean the operator has entered an invalid account number.

Fixed Length Record

A fixed length record has same number of bytes in each record (and same number of fields).

Word

A group of bits that can be addressed as a single unit by the CPU. A computer using a larger word size would generally operate faster.

Pipelining

A hardware feature that speeds up the execution of instructions

Lookup Tables

A limited set of values from which a particular field should be chosen, doesn't allow database users to make up their own entries

Linear Search

A linear search starts at one end of a data structure, working its way to the other, examining each element in the structure in order.

Extranet

A network configuration that allows selected outside organizations to access internal information systems

Deleting (Sequential)

A new copy is made of the file. Records are copied across to this new copy one at a time. When the turn comes of the record to be deleted, it is simply not copied over.

Deleting (Serial)

A new copy is made of the file. Records are copied across to this new copy one at a time. When the turn comes of the record to be deleted, it is simply not copied over.

Adding (Serial)

A new record is simply appended to the file (append means added to the end of).

Parallel Bus

A number of wires travelling in the same direction

Optical Mark Reader

A piece of paper to look for marks in pre-determined places, usually indicated to the user by way of pre-printed boxes to fill in. For example multiple choice questions, and the lottery.

Database Management System (DBMS)

A piece of software that sits between the application (the program the user works with) and this file system.

Driver

A piece of software whose job it is to ensure the device and the computer can be understood by one another.

Pivot Tables

A pivot table is a table that produces a user friendly summary of a large amount of data.

Mouse

A pointing device central to WIMP interfaces

Handshaking

A pre-planned system of signals designed to check that each device is ready to send/receive signals.

Processor's Components

A processor contains: - Arithmetic Logic Unit (ALU) - Control Unit (CU) - Registers

Records

A record is a data structure that contains a number of variables that hold related data. These variables do not all need to possess the same data type as each other

Scanner

A scanner shines beams of light at a document and measures the colour and intensity of the light that bounces back. Scanners are often used in conjunction with optical character reader technology.

Disc cache

A section of main memory between the CPU and disc where data recently read from disc or about to be written to disc is (temporarily) stored (before being transferred RAM).

Program

A sequence of instructions that a computer can interpret and execute. It is made up of modules

Protocols

A set of rules that computers must follow in order for the communication to be successful.

Bit

A single digit (in a binary number) for example 0 or 1

Variable

A space reserved in memory for storage of a single piece of data of a particular data type. The key feature of a variable is that it can be changed during program execution.

Macros

A stored set of instructions, accessed via hot key/tool bar/button/shortcut, may be built-in or created by user. For example may be built in, such as print button

Templates

A template is essentially an empty document. It will typically be a document that would be used lots of times.

Disadvantages of Paper Based

A. Difficult and/or time consuming to find customer details NOT just 'difficult to search' alone B. Paper based systems are difficult and/or time consuming to back up as each piece of paper will have to be copied NOT just 'difficult to back up' alone C. Time consuming to amend or create customer and/or car details D. Difficult to sort customer and/or car details (into a useable order) NOT just 'difficult to sort alone E. Writing can be illegible

Bus Topology

All devices are attached to a common connection medium, known as the backbone. Any communication must travel through this shared medium.

Star Topology

All devices are connected to a single central device, such as a hub or switch. Communication must go via this central device.

Searching Algorithm

An algorith that looks at the contents of a data structure (such as an array) to see if a specified piece of data is contained within it. The output of a searching algorithm should either be the location of the item being searched for (such as an array index) or a message stating that the item could not be found.

Random File

An algorithm is applied to the record key to produce a disc location (random files cannot be stored on tape). Random files are much faster to access than indexed sequential files, but they are not ideal to be applied to files that need to be regularly updated, as the structure of the disc can become disorganised.

One-Dimensional Array

An array in which each data item is accessed by specifying a single index.

Array

An array is a collection of items, each item being of the same data type. The size of an array is decided, in advance, as the array is created.

Two-Dimensional Array

An array made up of rows and columns; each element has the same data type and is identified by a unique combination of two subscripts: a row subscript and a column subscript

Three-Dimensional Array

An array that contain rows, columns and multiple tables with the same row and column headings. Must contain the same data type and has three subscripts.

Analogue Signal

Are continuously variable, meaning they can take a range of values and any value in between. Although they take up more bandwidth and are not high tolerance (0.00564 could more easily be mistook for 0.00563), they were made use of earlier in technological history

Keyboard

Are used in a large number of data-entry applications. Skilled users can enter data at a high speed, but errors can be quite common.

Adding (Sequential)

As files must be in key order, a new copy is made of the file. Records are copied across from the old to the new. When the point is reached for the new record, it is added to the copy. Then the remainder of the records on the old copy are copied to the new copy.

Analysis Of A System

As part of analysis, the following steps may be taken: •Using the current system as a current user might use it •Studying system documentation, including instructions and technical specifications •Interviews/questionnaires of customers/staff to seek their opinion and input •Observing the current system in use •Exploring data requirements •Producing diagrams showing processing and entities •Producing data flow diagrams

Adding (Random)

As the records do not need to be stored physically in sequence, a new record can be added anywhere on the disc where there is room.

Deleting (Random)

As the records do not need to be stored physically in sequence, a record can be deleted without the need to move or disrupt anything else on the disc.

Changeover

At which the user transitions from the old system to the new system.

Cache Memory

Cache memory is extremely fast and is used for regularly used program instructions or data, or pipelining

Boolean

Can be either true or false - requires only one bit of storage

Beta Testing

Carried out by prospective purchasers of the finished product. Beta testing is when a version is released to a number of prospective customers or general public in exchange for their constructive comments.

Acceptance Testing

Carried out by the customer to ensure that the system works correctly. This type of testing is intended to answer the question 'does this program do what I wanted it to do' rather than 'does this program work'.

Alpha Testing

Carried out by the developer (or a tester working for the same employer). Alpha testing is the issue of the software to a restricted audience of testers within the developer's own company. Individual algorithms are tested, with the values of variables being traced through the program, often line-by-line. This type of testing makes use of trace tables, where expected variable values are compared with the actual outcome.

Presence Check

Checks that something (anything) has been input.

Type Check

Checks that the appropriate data type (number, date, etc.) was adhered to.

Magnetic ink character recognition

Cheques have numbers printed at the bottom in magnetic ink, which is an encoded means of identifying who wrote the cheque. This speeds up processing, as these numbers do not need to be manually input, and the magnetic ink makes cheques hard to forge, thus increasing security.

Command Line Interface (CLI)

Command line interfaces typically require only typed input from the user, who must learn a set of commands before they are able to use the operating system. One such interface is MS-DOS 6.0, which is operated by typing in commands

Zipping

Compressing individual files is useful, but it is a process that can also be applied to groups of files, entire folders, or even groups of folders. Programs such as WinZip or WinRar look for patterns in the storage of the files and attempt to reduce file sizes losslessly. The result is a single file which can be easily transmitted, and is normally smaller than the original files that make it up.

Compression

Compression is a tool designed to minimize the amount of disc space taken up by a file by changing the way data is stored. Virtually any type of file can be compressed, although most compression techniques apply to either images or sound recordings. Ideally, compression will shrink the size of the file on the disc, without losing any of the data.

Serial File

Data is stored in the order in which it is received. This is useful if the data would be needed in this order (such as in a file to keep track of credit card transactions in date order), but less useful if a user needs to locate a particular record, as each record would need to be examined in turn. This type of structure is ideal for storage on tape, but can also be stored on disc.

Magnetic Strip Reader

Data is stored magnetically on an area of a flat surface. When the flat surface is read by a specific reader, the data is retrieved. This technology is widely used in credit/debit cards and tickets for trains

Data Validation

Data validation is carried out automatically to ensure that data is sensible though not necessarily correct Data is valid if it obeys all the rules set for that particular piece of data.

Real

Decimal numbers - more storage space would be required for either larger numbers or numbers stored to a higher degree of precision

Disc Defragmentation

Defragmentation moves file segments, physically, from one disc location to another, in an attempt to minimise these gaps and to ensure that files are stored, as much as possible, in a single location. This reduces disc access time, making disc access speed faster.

Rogue Value

Deliberately invalid result of a function, used to indicate some kind of exception.

Design Of A System

Designing a new system is typically split into a number of sections: •Designing algorithms - algorithms must be well designed, as this can affect the speed of a process such as searching or sorting •Designing HCI (human-computer interface) - this involves the design of how the computer and human will interact with each other, involving hardware (mouse or keyboard input; screen or printed output) and software (form design and layout, mapping keys on the keyboard to their functions). •Designing data structures - files and records must be designed (including serial vs sequential organisation, fixed vs variable record/field length) •Producing design documents

Data Store

Disc or tape. If a process requires data, other than the data provided by any external entity, it will come from a data store. Open ended rectangle

Dot-matrix printers

Dot-matrix printers have print heads that impact upon the paper, transferring a small amount of ink with each impact. As these printers generally have a very low resolution, they are usually used only for printing characters rather than images.

Ring Topology

Each device is connected to two other devices, so that the devices and connection media make up the shape of a ring (in practice, it is rarely round - it may pass from desk to desk in an office). To communicate with a particular device, a signal often has to pass through several other devices en route.

Transmitting with Buses

Each wire can transmit one bit at a time, so the more wires in a bus, the more data it can transmit at any one time. Buses need to transmit signals at the same time as one another to perform any but the simplest operations

Phased Changeover

Elements of the new system are introduced one-at-a-time

Lookup Check

Ensure data is valid, the user might select a value from a list, rather than typing.

Maintenance

Ensuring the product continues to be of optimal benefit to the customer

Feasibility Study

Examines the viability and probability of success for a considered product or project; might also look at the technical issues related to the project and determine if the technology proposed is feasible, reliable, and easily assimilated into the organization's existing technology structure.

Selection

Executing selected code if a condition is met

FTP

File Transfer Protocol. This is how files are moved from one computer to another across the Internet.

Installation guide

How to install the system and configure it for initial use.

HTTP

Hypertext Transfer Protocol. This is the set of rules governing how hypertext (the language of the worldwide web) is moved around the Internet, from device to device.

Data bus

If a piece of data is being transferred from memory to the processor to form part of a calculation

Mail-Merge

If an identical letter needs to be sent to many recipients with different names and addresses, the mail-merge feature of a word processing package • inserts item from separate Database • into the appropriate point in a standard document

File Hierarchy

If files are stored in a hierarchical structure, they are quicker to be searched through and can be found easier if the user is looking through each subdirectory manually. The top level of the hierarchy is called the root directory, beneath which are subdirectories.

Lossy Compression

In contrast to lossless compression, lossy compression refers to a technique of shrinking file sizes by giving away some precision of detail. JPEG images are an example of a file that is compressed this way. By reducing the quality of a picture when you save it, you can make the file size smaller.

Program documentation

Including annotated code and design of data structures, must be available to the developer during testing and maintenance

Systems Specification (Documentation)

Including data flow diagrams, entity diagrams and hierarchy charts are developed during the design stage to allow both the developer and the customer to have a handle on the intended finished product as early in the process as possible

Inkjet printers

Inkjet printers work by squirting ink (with great precision) directly onto the page from close range. Used in the home

Subroutines

Instructions for implementing a subtask within a larger task governed by a routine

Formulae

Instructions for the computer to carry out a calculation. Normally used in excel or other spreadsheet software

Telecommuting

Involves performing some or all of the job away from the business through technological communication devices.

Primary Key

Is a key in a relational database that is unique for each record. It is a unique identifier.

Digital Signal

Is discrete - it can contain 1s and 0s - nothing more, less or in between. Digital signals are high tolerance (it is not easy to mistake a 1 for a 0 or vice-versa) and occupy very small bandwidth

File

Is made up of records and fields.

Modem

Is needed to translate analogue to digital and vice-versa. This is a necessary piece of equipment when a digital computer needs to make use of an analogue telephone network to access the Internet.

Adaptive maintenance

Is usually carried out to reflect external changes or operate with new hardware / Operating System

Laser Printer

Laser printers use a laser to fuse a powder known as toner to the page. Colour laser printers are becoming continually more affordable, and high-end commercial printers can print thousands of pages per minute.

Perfective maintenance

Making the system easier to use or adding new features; in short, making the system as good as it can be for its particular purpose

RAM cache

Memory between the CPU and main memory (sometimes referred to as L2 or L3 cache) where sections of (recently or frequently used) data and/or programs are stored

Read Only Memory (ROM)

Memory cannot be changed or deleted. The contents of ROM are safe when a computer loses power (making ROM non-volatile). ROM is used to store the bootstrap program, which is needed to start up the computer, as well as any system data that does not change.

User manuals

Must be available to the customer by the implementation stage to provide details on how to operate the system, including instructions, screenshots, descriptions of the interface and meanings of error messages. Contents of user documentation include: Detailed instructions on how to navigate (find features), input data, produce reports, save, delete and edit files, and what actions to take when error messages are produced.

Operating System

Operating systems are a vital layer of software, acting as a buffer between the user and the physical components of the computer. Without an operating system, the user of a computer would need to perform a multitude of extra tasks.

Random Access Memory (RAM)

Otherwise known as main memory, this is the component of a computer that stores programs that are currently being executed or data that will be needed for immediate use. RAM is volatile, and contents are lost if the computer loses power.

VoIP

Over Internet Protocol. This protocol allows the Internet to be used as a phone network; users with microphones and headphones can talk to one another this way.

Plotters

Plotters use pens and mechanical hands to draw an image onto the page one line at a time. As these devices are not restricted by resolution, they are favoured by designers and engineers.

POP3

Post Office Protocol Version 3. This is a protocol for accessing e-mails and is commonly used in Microsoft Outlook to take the e-mails from an online location, opening them in the Outlook environment.

Corrective maintenance

Problems that occurred during the creation of the new system that were not discovered at the time; ironing out bugs

Log of results

Produced in an ongoing cycle, until the system is deemed to be working correctly

Sequential File

Records are organised in order of their key field, which makes searching for a particular record much faster using a binary search (see the 'Algorithms and Programming' section). Again, this type of file can be stored on tape or disc.

Indexed Sequential File

Records are split into two parts. The first part contains the record key and a link to the disc location of the rest of the record. The second part, stored elsewhere on the disc, contains the rest of the record. This type of structure is ideal for regularly updating records, as they can be easily located without examining the whole of each record. This type of file cannot be stored on tape.

Repetition/Iteration

Repeating the execution of code until a condition is met

Control Unit (CU)

Sends control signals both within and beyond the CPU to control the behaviour of other components

Control Bus

Sends signals to devices, such as memory, to control the actions that they carry out

SMTP

Simple Mail Transfer Protocol. While POP3 might be used to retrieve e-mails, SMTP is used to send them from one server to another.

Subtask

Smaller tasks that are completed by a subroutine.

SSD Defragmentation

Solid State Drives do not suffer from fragmentation problems. They can access data more quickly because there are no moving parts.

Adding (Indexed Sequential)

The key part of the record must be added in the same way as in a sequential file. The rest of the record can be stored anywhere on the disc, as it will be pointed to by the key part.

Deleting (Indexed Sequential)

The key part of the record must be deleted in the same way as in serial or sequential files. The rest of the record can be deleted without the need to move or disrupt the rest of the contents of the disc.

Word Length

The larger a computer's word length, the more complex a calculation it can carry out in one go. A computer's word length is also usually the size of any one of its CPU registers.

Local Scope

These variables are declared within a function or module and their values can only be accessed by code within the same function. When a function finishes running, any local variables within cease to exist.

Cell Referencing

This is used in creating formulas. This allows you to link your formula to a specific cell instead of a number. It usually made up of a letter then a number. ($G10) stops up and down replications, (G$10) stops right and left replications, ($G$10) stops replications altogether.

Range Check

This would apply to numerical fields, allowing them maximum and minimum values. Fields containing prices or quantities might have this type of check.

Technical manuals

To detail such things as security procedures, backup procedures and system recovery procedures, these describe how and when data is (or should) be backed up and how to recover the data in event of loss. -Contents of backup and recovery procedures documentation include: -When data is backed up -Where data is backed up -Clerical procedures to follow after back up, for example how to securely store backed up data -Instructions or steps to recover data after loss

String

To store any number of characters - variable length

Touchscreen

Touch screens are designed to be a means of two-way communication between a computer and a human user. Data can be output to the touch screen in the same way it would be output to a standard VDU, but the user inputs by touching parts of the screen instead of clicking on them with a pointing device.

Sorting

Unlike searching, which examines a data structure, leaving it unchanged, a sorting algorithm changes a data structure by arranging its contents into order.

Speakers

Used for the output of sound, speakers form an integral part of a number of systems. In music production, they are vital for obvious reasons; in computer gaming, music and sound effects can add to the experience

Light Pen

Used to interact directly with a screen. Can be used for drawing designs straight onto a screen or for quickly navigating through a menu structure. The pen recognises which pixel of the screen it is pointing at and sends a corresponding signal to the computer to change the display in some way.

Monitor

VDUs (visual display units) are cheap and are familiar to most users. The majority of computer systems have a VDU attached at some point.

Format Check

Validation that requires a certain and unique combination of letters and numbers e.g Postcode

Global Scope

Variables are declared outside of any functions. Global variables are normally declared early in the code, typically all together. The value of a global variable can be accessed or changed from anywhere within the program code.

Data Verification

Verification checks exist to make sure data is consistent or not corrupt

Writing to a Disc

When a disc has been written to and re-written to several times, files may not be stored as efficiently as they might be, and files can be split and spread across the disc, increasing disc access time. If a disc is nearly full it may not have enough space together to store the file (there are not enough consecutive blocks available on the disc).

Query

When data in the database is manipulated and presented in such a way that it answers a question asking to present data under conditions.

File Attribute

When files are created, they are given two components to be used to identify them. The first is the file name (such as 'Letters') and the second is the extension. File extensions are usually two to four characters in length and describe the type of data contained within the file.

WAP

Wireless Application Protocol. This is not a formalised standard yet, but this protocol allows users to access information using portable handheld devices such as PDAs and mobile phones.

Operating System Tasks (Manage Backing Store)

o Ensures that data is stored and can be retrieved correctly from any disc drive o Creates and maintains Filing system such as FAT or NTFS (accepted but not expected) o Organise files in a hierarchical directory structure. o File compression: - The amount of data is reduced and the file is made smaller - Compression is used to save disc space o Disc de-fragmentation : - Fragmented files are split up and stored on different parts of the disc - Disc fragmentation will slow down disc access speed - Disc de-fragmentation is when file parts are physically re-arranged (re-organised, moved, re-ordered) on disc (into the order required for access)

Features of a DBMS

• An ability to check the data for inconsistencies • An ability to minimise duplicated data (a major purpose of a database is to ensure each piece of data is stored only once, thereby reducing potential errors) • An ability to obtain related data from different tables in the file system by linking these tables to one another

CLI Advantages

• Can be installed on less advanced machines, as there is less need for an interface requiring advanced graphics or an abundance of memory and backup storage • Run very quickly, particularly when used by an expert user

Voice Recognition Advantages

• Car driver can operate audio device without hands or eyes leaving the steering wheel / touching device • System would have a limited set of commands so easy for car driver to learn • System would allow car driver to create their own distinct commands and contact names for the mobile phone so driver can use system all the time not just for some functions • Allows mobile phone to used legally while driving / not have to stop car to make a call

Benefits of a DBMS

• Data can be accessed speedily and manipulated to form new data • A single database can be shared, internationally if need be • Data validation can help to ensure good quality data • Data duplication can be avoided • Security of data can be centralised

Bus Topology Disadvantages

• Failure in the main cable will cause failure of the network • The network can be significantly slowed by high network traffic

Ring Topology Disadvantages

• Failure of a single cable can bring down the entire network • Failure of a single device can bring down the entire network • Security is not ensured, as data passes through other devices en route to its final destination

Fixed Length Factors

• Fixed length record is easier to program as it can be calculated to know how much storage space will be required • Fixed length records are quicker to process (read/write) by computer as start and end locations are known • Fixed length record wastes storage space as fields have blank space • Fixed length record will truncate long fields

Star Topology Advantages

• If one cable fails, only the device attached to it is isolated from the network • Faults are easy to find • It is easy to add extra devices • The system is secure, as data is only sent to devices that need that data

GUI Advantages

• Instinctive to use - most users could ascertain the purpose of the recycle bin without reading any instructions • A beginner does not need to learn a set of commands, as in command line interfaces

Star Topology Disadvantages

• Lots of cable, which means more expensive to install than other topologies • Expense of buying switch • Switch has to be configured and/or managed • If switch / hub goes down network will fail

Ring Topology Advantages

• No collisions, as there is typically only one batch of data allowed on the network at any one time • Very high rates of transmission are possible

Pivot Table Uses

• Querying large amounts of data in user-friendly ways • Subtotalling and aggregating numeric data, summarising data by categories and subcategories, and creating custom calculations and formulas • Moving rows to column or columns to rows (or 'pivoting') to see different summaries of the source data • Filtering, sorting, grouping, and conditionally formatting the most useful and interesting subset of data to enable you to focus on the information that you want • Presenting concise, attractive, and annotated online or printed reports

Voice Recognition Disadvantages

• The driver will have to learn the pre-existing commands which will take time • Some drivers have used poor systems or are scared of new technology and feel that it is not worth the effort • The software may not recognise commands as background noise is more likely to interfere with words in a car • The driver might have a cold or sore throat or a speech impediment and the system will not recognise the commands

CLI Disadvantages

• Users are required to learn an instruction set before they can use the interface

Variable Length Factors

• Variable length record makes it difficult to calculate how much storage space will be required • Variable length records are slower to process (read/write) by computer as start and end locations have to be calculated at read/write time • Variable length record saves storage space as no blank space • Variable length record avoids truncation as each field can extend to accommodate any number of characters

Bus Topology Advantages

• Very cheap, as it requires a minimal amount of cabling • Easy to add or remove computers

Malicious Damage

•A hacker gaining access to a system and changing/deleting information •A virus, Trojan horse or worm being introduced to a system •An employee of an organisation damaging or destroying data for their own gains

Backup Recovery

•A medium to contain the copy of the data. This is typically a removable hard disc, a tape cartridge or an online location. •A routine for backing up data. It might be monthly, weekly or daily, depending on the importance of the information and the possible disruption by losing it. •A safe location to store the data. If it is backed up online, this is not an issue. If you have a tape or a hard disc, it should be stored off-site in a fireproof safe. •A means of returning the data from the backup location to the main server/computer, should it become necessary. This may be as simple as copying from the backup medium to a new server/computer, should data become corrupted.

Accidental Damage

•A person accidentally deleting a record •A computer or server crash •A loss of power before a file was saved •Destruction of equipment due to fire or flood

Protection against Data Loss

•Backup procedures. Regular backups should be taken and stored off site or in the cloud •Passwords - More complicated combinations are harder to guess •Levels of permission. a low ranking employee's password would not grant them the permission to delete files •Write-protect mechanisms - storage devices can be physically set to not allow data to be deleted or altered in any way

Direct Advantages and Disadvantages

•Could be used where a failure would not be catastrophic •Can be cheaper to implement •New system is available immediately if required •Can be the least disruptive if implemented well •New system may not work as well until staff are fully used to using it •If new system fails organisation have no system which could be costly or dangerous

The Data Protection Act (1998)

•Data must be adequate, relevant and not excessive •Data must be accurate and up to date •Personal data stored for no longer than necessary •Processed in line with your rights - individual can check and amend data •Held securely •Data can only be transferred outside EC to countries with adequate DPA •Data is fairly and lawfully processed •Data is processed for limited purposes

Email Disadvantages

•E-mails can spread viruses; forwarded e-mails pose this problem in particular •E-mails can often be ignored by their intended recipients if they are perceived as spam (junk mail) •E-mails take up bandwidth to be sent and inbox space, which the recipient might not be happy with •E-mails are often seen as contributing to a decline in the quality of written language, as people often abbreviate words (such as L8R) •E-mails have social implications if used in a situation where e-mailing has replaced speaking to colleagues in a busy office

Study Activities and Outcomes (Company)

•Hardware requirements will be considered •Legal, social and environmental issues are considered •Whether the project is technically feasible - does the technology/skills exist to complete •Whether the project can be completed in the time scale - acceptable or projected time scale for the solution produced •Whether the project can be completed on budget - the projected cost of the solution •Involves a cost-benefit analysis to decide if a solution is affordable •Training requirements for staff on the new system are considered

Forums and Chat-rooms Disadvatages

•Information on the Internet is not necessarily there courtesy of a reliable source. •People in chat rooms and forums are not necessarily who they claim to be. •There is less emphasis on social skills in a chat room or a forum. •Instead of providing a means of working, online features such as these are often a distraction from working •As in e-mails, viruses can be transmitted, although this is much more likely of the Internet than an intranet or extranet

Replacing A System Costs

•Money for software developers, hardware, etc. •Time - designing and installing a new system is very time consuming •Human resources - specialist staff are needed to design and install the system; existing staff would need to be re-trained to operate it

Study Activities and Outcomes (Preparation)

•Observing/using the current system in operation •Consulting current documentation •Carry out a questionnaire of staff/customers •Interview staff/customers/employees •A description of the problem/detailed system requirements •Different possible methods of solution identified •Storage requirements are considered •Different types of HCI considered

Health & Safety

•Repetitive Strain Injury (RSI) from performing the same physical act many times •Back trouble can result from sitting for extended periods at a badly organised •Eyestrain can result from spending too much time looking at a monitor, particularly in poor lighting. •Epileptic fits can be triggered by the flickering appearance of certain screens

Parallel Advantages and Disadvatages

•Safest option as if new system fails they still have existing system •Expensive as require temporary staff or overtime for current staff to operate both systems •Could cause confusion for staff and customers having two systems •New system is available immediately if required

Phased Advantages and Disadvantages

•Suitable for different departments •All staff can focus on one area to resolve any problems •Problems can be fixed quicker as more experts to resolve problem •Difficulties identified in one area can be resolved and managed in next area •Might cause problems in the changeover period when they need to communicate with each other and have different systems •Slower to get new system up and running compared to some other methods

Pilot Advantages and Disadvantages

•Suitable for different offices •All staff can focus on one area to resolve any problems •Problems can be fixed quicker as more experts to resolve problem •Difficulties identified in one area can be resolved and managed in next area •Might cause problems in the changeover period when they need to communicate with each other and have different systems •Slower to get new system up and running compared to some other methods

Variable Length Record

A variable length record has different number of bytes in each record (or different number of fields).

Direct Changeover

Also known as 'big bang', when the changeover is sudden and complete

Games controller

Although primarily an input device, modern games controllers provide feedback to the user by vibrating.

Optical Character Reader

An OCR device can recognise and interpret characters on the page. This technology is most reliable when dealing with printed characters, but handwritten characters can also be recognised. This is highly useful in scanning postcodes at mail sorting offices.

Parallel Changeover

Both systems run at the same time for a while; this is beneficial because, in the event of a problem with the new system, the old system is still available for use

Modules

Breaking the programming into logical, manageable portions. Made up of subroutines

Registers

Contains, at any one time, a single piece of data, such as the memory address of the next location to be executed.

External Entity

Typically a human user. One rectangle overlapping another

Secondary Storage Factors

Factors are: -Speed (How fast data can be accessed) -Cost Per Storage Unit (How much per MB or GB) -Durability (How strong or tough is it) -Portability (How easy it to move it from one computer to another

Internal Hard Disks Factors

Fast & cheap, but not portable

Length Check

Fields have a maximum length and some have a minimum. Telephone numbers, for example, would be subject to both.

Tape Drives

High capacity but slow, as the data required may be at the other end of the tape

Touchscreen Advantages

-Touch screen is intuitive and easy to use and users may be familiar with concept -Whole screen on the device can be used for input such as a large keyboard -Touch screen is very versatile and it can be used for interactive multimedia applications such as playing games -Users can easily zoom in on small text or to see more detail -No need for a method for input and one for output therefore device can be kept small / less weight

Mod 11 Check Digit

1. Each digit of the code number is assigned a 'weight'. The right hand digit is given a weight of 2, the next digit to the left 3 and so on 2. Each digit is multiplied by its weight and the products added together 3. The sum of the products is divided by 11 and the remainder obtained 4. The remainder is subtracted from 11. If the remainder is 10 use the Roman numeral 'X' 5. The answer is the check digit, add it onto the end of the original code

Fields

A single item of data.

Character

A single letter, number, punctuation mark, space, etc. - requires one byte

USB Pen Factors

Portable & durable, but a high cost for such a small memory capacity

Process

Such as a calculation, sort or filter. A rounded rectangle

Bubbles Sort

The bubble sort is one type of sorting algorithm. It works by taking each item in a data structure in turn, and moving it as far along the data structure as it should go.

Barcode Reader

The image of a barcode translates into numbers which are read into a system and searched for in a database to find data on the object displaying the barcode. Barcodes do not require high-quality printing techniques and can be put onto surfaces that are not flat. If the barcode is damaged, a human user can simply input the number itself into the system manually.

Arithmetic Logic Unit (ALU)

The part of the CPU that performs arithmetic computations and logical operations.

Updating Sequential Files

The process requires the original file (known as the old master) and a file containing updates to be made to the old master (known as the transaction file). As long as records are stored in the same order on the old master and the transaction file, the process of updating the old master (to produce the new master) should require only one pass through the files.

Processor

The processor is an essential part of any computer. It has two main purposes: • To perform arithmetic calculations (+ - * /) and logic calculations (AND, OR, NOT) • To follow program instructions, thereby executing programs

Double-entry verification

The same data is entered twice, often by two different operators. One is then checked against the other. If the two entries don't match, they must be re-entered, twice. Example of this is password setting.

Pilot Changeover

The user may be a large company with many departments. In this type of changeover, a single department would change directly to the new system, and then the rest of the organisation would follow later.

Graphical User Interface (GUI)

These interfaces communicate with the user by way of images. The most common type of GUI is a WIMP (Windows, Icons, Mouse, Pointer) interface. A user interface based on graphics (icons and pictures and menus) instead of text

Constants

They can store a single piece of data of a particular data type. They do not change during program execution; they remain the same.

Address Bus

When the processor wants a piece of data from a particular location in memory, it transmits this location along the address bus. Unlike data and control buses, address buses transmit signals only in one direction (unidirectional).

Interfacing

Where devices need to communicate with one another (such as a PC sending a job to a printer), it is necessary for those devices to interface with one another

Integer

Whole numbers - the more storage space is available, the higher the largest number that can be stored

Internet or web cache

stores previously viewed pages on disc storing 'pre-fetched' pages (from information provided with page being viewed other pages are downloaded and cached in anticipation that the user might view them) and storing pages in anticipation of not having internet access in future so pages can still be viewed.

GUI Disadvantages

• A lot of processing power is used on displaying icons rather than text • High RAM and backup store capacities are required • A good graphical display is essential • Typically, GUIs run slower than command line interfaces

Drawbacks of a DBMS

• Centralised data can be easier to steal than decentralised data • If data is not correct, it filters through to all users of the data

Email Advantages

•Senders can save paper, time and money by not using a postal service instead •It is more environmentally sound, as no paper is used, and no fuel is expended to physically move a letter from one place to another •E-mail addresses can be arranged into groups and the same message can be sent instantly to an entire group (these are also known as a distribution lists) •People can reply quickly and easily to an e-mail with very little hassle •Attachments can be sent, including image, video and sound •Links can be sent, allowing a reader quick access to a particular web page

Forums and Chat-rooms Advatages

•Students can find answers to questions •Like-minded people relate to peers better than parents, bosses, teachers, etc. •Collectively, a group of people will possess far more information than any one individual •It can be a cheaper form of communication than telephoning •It is also beneficial to talk to many people at once; it can be used for brainstorming a new idea in a way that a telephone cannot