Comp sci unit 3

Is used to transfer actual data

Is used to transfer information about where the data should reside in memory

Is used by the CPU to communicate with devices that are contained within the computer. This occurs through physical connections such as cables or printed circuits.

The number of bits the computer can transmit at one time.

An alternate name for the Fetch-Execute Cycle

Obtaining the program instruction or data item from memory.

The process of translating the instruction into signals the computer can execute.

The process of carrying out the command. The ALU executes the instruction.

The process of writing the results of an instruction into memory.

When a processor can retrieve the next instruction before it completes the machine cycle for the previous instruction.

Software system located on networked computers coordinate and communicate their actions by passing messages.

Running a single task on a single processor.

Involves the concurrent computation or simultaneous execution of processes or threads at the same time.

The use of multiple cores inside a processor to increase the performance of the CPU.

A documented process or procedure to recover and protect a business' IT infrastructure in the event of a disaster.

A set of tests run in a controlled environment to measure the performance of a specified computer component.

Performs arithmetic, comparison, and other operations through the use of logic gates.

The CU directs and coordinates most of the operations of the computer. It also Interprets each instruction issued by a program and initiates the appropriate action to carry out the instruction.

Small, high speed storage locations that temporarily hold data and instructions that are currently being used.

A low capacity, high speed storage location.

A register that contains the address of the instruction being executed at the time.

A small quartz crystal circuit that controls the timing of all computer operations.

OS designed to operate on small machines, such as PDAs or autonomous electronics with reduced autonomy.

An OS that runs on personal computers and mobile devices.

An OS specifically designed for use on a server.

A Software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions.

The method and structure of which data is stored on a storage device.

A specified collection of software and hardware to applied across and office or organisation.

A copy of the entire state of a computer system.

Waterfall/Cascade - A system development methodology that approaches the process of system development in a very structured manner.

RAD - A system development methodology that uses minimal planning in favour of rapid prototyping.

A linear system of defined stages each of which requires completion before commencement of the following stage.

The planning phase for a project during which the decision-making body for the organisation, called the steering committee, receives a project request.

Occurs during the Preliminary Analysis phase of the SDLC and involves reviewing and approving the project requests and prioritizes the project requests.

A Measure of how sustainable the development of a system will be to the organisation

Whether the organisation has or can obtain the hardware, software, and people to deliver and then support the system.

Also referred to as costenefit feasibility. which measures whether the lifetime benefits of the proposed system will be greater than its lifetime costs.

Measures how well the proposed system will work.

Measures whether established project deadlines are reasonable.

Considering legislation.

The second stage of the SDLC during which the current system is modelled to identify weaknesses and possible improvements. It also defines the requirements of the new system.

The third stage of the SDLC during which the logical and physical elements of the system are designed. This stage is where DFDs, ERDs, Pseudocode and CASE tools are used.

The fourth stage of the SDLC during which the actual development of the system including hardware acquisition, construction and testing and the creation of system documentation.

The fifth stage of the SDLC when the new system is implemented into the organisation and documentation is finalised.

Suddenly switch everyone over to the new system. The cheapest option if it works however is also carries a high risk.

Gradually introduce discrete aspects of the new system over time. Users learn the new system, can cope with changes, problems can be managed.

Run new and old systems simultaneously until you are sure the new system works. Requires a lot of extra work from the users (as everything must be done twice). Has the potential to require the employment of temporary hires to handle double workload.

A small number of competent users try the system first, everyone else stays on the old system until all bugs have been fixed.

A tightly isolated software container that can run its own operating systems and applications as if it were a physical computer.

The centralisation of applications at a data centre.

Where a single physical computer simultaneously runs multiple virtual PCs, each with its own operating system and suite of applications.

Where multiple logical servers are hosted on the one physical computer.

Where many physical storage devices appear to the user as a single logical storage device.

The on-demand availability of computer system resources over the internet instead of using them locally.

The combination of multiple uses into one product e.g. a smart phone can act as a GPS, Music Player and telecommunications device.

Breaking down a project into manageable tasks.

Allocating certain amounts of resources to certain timeframes or stages of development

Allocating time to certain stages of development.

Making sure the project is on track to reach its time goal.

A set of processes that guide you throughout a project.

Consists of cost, time and quality. It refers to the 'size' of the project.

- It is easy to understand, use and manage as each phase has specific deliverables- A review process of each stage occurs before progressing to the next phase- Phases are completed one at a time and each phase does not overlap- Waterfall model works well for projects where requirements are very well understood

- Requires a reduced development timeEnables the reuse of program components- Permits the quick review, analysis, and rework of each stage- Encourages client feedback and engagement from the start, ensuring ease of system integration- Works well with projects with short implementation times and high staff availability- Suitable for systems that are modularised

A set of software application programs, which are used to automate SDLC activities.

- A reduction in the cost and time taken to deploy, configure, maintain, support, and manage computers.- By standardising the hardware and software platforms used within an organisation, an IT department or service provider can deploy new computers and correct problems with existing computers quickly.- A standardised, repeatable, and automated solution creates a known, expected, and supportable environment.- A standardised solution ensures maintaining known outcomes, with automation fostering speed, repeatability, and standardisation. Fixes can be deployed easily as a standard environment ensures compatibility.

- Users may be forced to use software or operating systems they are not familiar with.- Users may not be able to use specialised software they need.- A network administrator may need to be hired.- Does not encourage innovation.

- Scheduling- Managing Concurrency- Managing Memory- Managing Devices

- Cost savings due to fewer physical machines and the maintenance of these- Energy savings as fewer physical machines mean less power and air-conditioning needed- Faster application and service delivery- Higher levels of business continuity as a virtual machine can be moved to another physical machine to provide additional capacity or overcome hardware issues.- Disaster recovery is quicker. You can move the virtual machines to another environment and access them as normal.

- It is usually a pay as you go model - few have upfront commitments to bulk space- It is very cheap - no need for a large hardware investment- No operational or maintenance costs- Easy transfer - if you have good internet connection- Easy access - from anywhere at any time on any platform- Data can be encrypted during transition- A huge choice of more than 2000 providers- Trained professionals looking after your data which may not be realistic on site due to cost

- The risks of cloud can be significant
- so selection of the provider is important.
- Confidentiality: There is simply some data that should not be on the internet.
- Security: some vendors do not offer encryption
-SLA (Service level agreements) can be patchy
- Data ownership: DropBox's conditions are that they own your data
- Slow Internet connection: especially for the first entire backup
- Provider going broke*: Generally, you are alerted and there is usually an automatic migration to a competitor
- If the internet connection goes down, you lose the services.

Platform as a service (PaaS) is a complete development and deployment environment in the cloud.

Infrastructure as a service (IaaS) is an instant computing infrastructure, provisioned and managed over the internet.

- Online Storage
- Incremental Backup
- Full Backup
- RAID (0,1,10)
- Uninterruptable Power Supply (UPS)

- Cost Savings
- Energy Savings
- Faster Application & Service Delivery
- Higher levels of Business Continuity
- Faster Disaster Recovery

- Pollution
- Consuming Resources
- Waste
- Disrupting Ecology
- Health Hazards

A Unit of digital information that consists of 8 bits

The singular term for data

Describes and defines the property of an object, entity or table.

A combination of one or more related characters or bytes and is the smallest unit of data a user can access.

Letters, numbers or special characters

Numbers only

Unique number assigned by the DBMS to each record added

Dollar or cents amount or numbers containing decimal values

Month, Day, Year and sometimes Time

Lengthy text entries

Only yes/true or no/false

Email or Web Address that links to a web page

Photo, Audio, Video, or a large document created in other programs

A record is a group of related fields or attributes.

A thing capable of an independent existence that can be uniquely identified. Can exist physically or logically.

How entities are related to one another

A group of programs that manipulate the database and provide an interface between the database and the user.

When there is more than one entry for a single piece of data

Inability to enter data without adding other information, which may not be directly related.

Inability to delete an information record without inadvertently deleting other indirectly related data.

Possibility of missing one of the copies of a record when updating data, causing inconsistent values for the same piece of information.

A database model concept used to design and describe a database.

Ensures relationships between entities are enforced. Ensures that data is of high quality, correct, consistent and accessible.

Every table must have a Primary Key that is unique and not null.

Ensures that for each foreign key there is a corresponding primary key or other unique field.

Ensures data values inside a database follow defined rules for values, range and format.

Protecting a database from destructive forces and the unwanted actions of unauthorised users.

- Has a distinct name
- There are no repeating groups
- Each cell contains exactly one atomic value
- Each attribute has a name
- The values of an attribute are all the same data type

A table has no repeating groups, that is, no single row has a column containing more than one value or more than one column with the same kind of value, for example phone1 and phone 2, car1 and car2

A table is in 1NF and any column that is not part of the primary key is dependent on the whole primary key.

A table is in 2NF and any column that is not part of the primary key is dependent only on the primary key and no other column.

Another name for a Foreign Key

The expression of the dependency of A on C when A depends on B whilst B depends of C

Not a Primary Key or a Foreign Key

An attribute chosen to represent all the data in the record. Must be unique for each record.

A Primary Key from another table used in a table to link data.

An API (Application Program Interface) is created which allows any user on any device to interact with a database.

The User Interface: A way for user to interact with the database.

A conditional search and retrieval or change in the data executed by a user.

Stating the columns from the table you want to return.

Stating what table you want the columns to return from.

Stating what condition the records must meet to be returned.

A command used to sort the data in ascending (ASC) or descending (DESC)

A command used to update data that already exists within a field.

A command used to delete data from a table.

A command used to insert new data into the database.

The Database has multiple copies of itself in multiple locations.

The Database has a single copy of itself in one, centralised location.

A collection of all data in an organisation located in a single source, used for analysis of trends.

Data marts are smaller, more specialised areas of a data warehouse.

Analysing large pools of data with the goal of discovering previously unknown patterns.

The process of duplicating data, be it inside or outside a database. Can be both good and bad dependant on the scenario.

All non-key fields must be functionally dependant on the whole key.

- Reflects organisational structure. Many organisations are spread over many locations
- Improved share ability and local autonomy. Users have local control of their data meaning they can establish and enforce local policies.
- Improved availability. One failure will not make the entire system inoperable and they can still function while a centralised database may shut down.
- Improved Reliability. In the event of the failure, data is also stored in other locations.
- Improved performance. Data is located near the site of greatest demand
- Economics: It is cheaper to set up many small devices rather than a single supercomputer
- Modular growth. Expansion is easy as each location can be fitted out with small devices rather than one large database.

- Complexity. Replication of data adds a level of complexity
- Cost. Ongoing communication and maintenance costs over many locations.
- Security. Communication makes data more vulnerable.
- There are many locations so data is not as secure.
- Integrity control is more difficult.
- Lack of standards. Effective communication standards are still emerging.
- Lack of experience. Industry inexperience with distributed databases.
- If two people are working on the same file at once, it may cause issues as to which instance is saved.

- Easier data administration. Data is all stored in one location
- Less data duplication. Data does not need to be copied across multiple locations. Only a few copies are needed including backups.
- Higher data integrity. There is only one collection of data that needs to be updated with the latest information.
- Greater data security. Data does not need to be communicated across a network which makes data vulnerable in the transfer.

- Bottlenecks may occur as a result of high traffic
- A hardware failure will result in data loss if there is no disaster recovery plan
- Less data redundancy than a distributed database so if data is loss, it is more difficult to recover

- Readability
- Navigation
- Logical Order
- Inclusivity

A communication solution for the large number of Operating Systems, Database Systems and applications written in different programming languages. There are three major components:
- Client
- Database Server
- ODBC Driver