computer science (mock) terms

What is a computer

A machine that takes data, processes it and then outputs it.

What is hardware?

The physical components that make up the computer system

What is software?

The programs that a computer system runs

What is an embedded system?

Computers built into other devices. They are usually dedicated systems.

Why are embedded systems also known as control systems?

They monitor and control machinery in order to achieve a desired result.

What are the qualities of embedded systems?

Cheaper to design, cheaper to produce, more efficient at doing their task (than general purpose)

What does the Von Neumann architecture describe?

A system where the CPU runs programs stored in memory. Programs consist of instructions and data which are stored in memory addresses.

In a FDE cycle, what occurs at the fetch instruction?

1)The control unit reads memory address of next CPU instruction.
2) The instruction stored in address copied from memory to one if the registers.
3) The memory address in control unit is incremented to point to address of next
instruction, ready for next cycle.

In a FDE cycle, what occurs at the decode instruction?

1) The instruction copied from
memory is decoded by control unit.
2) The control unit prepares for next
step, e.g. by loading other values into
registers.

In a FDE cycle, what occurs at the decode instruction?

The instruction is performed.

What three main factors does CPU speed depend on?

Cache, Cores, Clock speed

What does clock speed determine?

The number of instructions a single processor core can out per second.

What is the clock used for in the CPU?

Co-ordinates all of the components by sending out a regular electrical pulse to synchronise all the components

What is overclocking?

Increasing a clock rate to make them run at a higher clock speed than the factory set rate.

What are the risks of overclocking?

CPU can overheat, causing crashes or permanent damage to the system.

What is the Cache?

A small amount of high speed RAM built in the processor, much faster than RAM

What does a larger Cache size do?

Gives the CPU faster access to more data it needs to process.

What is Cache speed based on?

How far it is from the CPU - some stored on the CPU itself (fast), others stored on motherboard
(slower)

What is a core?

Processing unit(s) within the CPU, each core in a CPU can process data independently of the rest.

The more cores a CPU has...

The more instructions it can carry out at once, so the faster it can process a batch of data.

What are the downsides of multi-core processing?

Software needs to be designed to use multicore processing. Some processing tasks cannot be split between cores, some steps will depend on others, increasing communication needed between cores.

Other means of increased CPU performance are...

RAM, GPUS, and SSDs

How does RAM impact computer performance?

If too little RAM, may not be able to keep all application data loaded at once (slower). More RAM, more applications / more memory-intensive applications can smoothly run (faster)

How do GPUs impact computer performance?

handle graphics and image processing. Relieve processing load on the CPU, freeing it to do other tasks.

What does the CPU do?

Processes data and instructions, controls rest of computer system

What are registers?

Small amounts of high speed memory (fastest)

When are registers most commonly used?

The FDE cycle: processing address of next instruction to be executed, current instruction being decoded, and results of calculations

What does the ALU do?

Performs Arithmetic and Logical operations (decisions). Calculations and decisions are made here.

What is the ALUs secondary function?

Acts as a gateway between primary memory and secondary storage. Data transfer passes ALU.

What are buses and what are they used for?

High speed internal connections, used to send control signals and data between processor and other components

What does the control unit do?

The FDE cycle, issues control signals that control hardware, moves data around the system

What does a device driver do?

Acts as a translator for signals between the operating system and device

How do operating systems communicate with input and output devices?

When computer is booted up, OS chooses correct device driver for detected device. If new device connected, OS installs new, matching device driver

How are updates installed onto device drivers?

Manually by the user or Automically by the OS

How does the operating system manage applications?

Provides a platform for applications to run on, allows multitasking, allows application to access hardware and other peripheral devices as needed, provides a user interface that applications are accessed through.

What is multitasking?

Computer running multiple applications at once

What interfaces do most desktop computer use?

Commonly use GUIs (Graphical User Interfaces) that are WIMP Based

What does the acronym WIMP stand for?

Window, Icons, Menus, Pointers

What are GUIs most ideal for?

Use with mouse and keyboard, devices with different input methods, may have very different interfaces.

How does an operating system manage memory?

When application opened, OS copies necessary parts of an application to memory, followed by additional parts when required.

If application / feature used recently, kept in memory (else removed).

Manages how much RAM has access to (depends on program)

Makes sure applications do not overwrite or interfere with each other by allocating certain applications specific memory addresses - processes kept in separate processes

What are utility programs used for?

Maintain or configure a computer

How does the OS tell the CPU what to process?

Processes created once application launched. CPU carries out instructions one process at a time.

OS uses scheduling to determine most efficient order for CPU to execute instructions/ Each process allocated a 'priority', highest priority processes carried out first

How does the operating system manage system security?

User account control, granted or denied access to specific data/resources. Anti-theft measures, password/ pin protected, patterns, fingerprint/retina scanners

How does the operating system handle hard disks?

Splits the physical disk into storage sectors, decides which sectors to write data to, keeps track of free space on the disk. Also uses defragmentation software.

What is the DPA?

Data Protection Act of 1998, designed to control data handling, give legal rights to people with stored data, replaced with GDPR in 2018

What is the GDPR?

General Data Protection Regulation, tightened data protection laws, internationally followed

What is a data controller?

Ensures the organisation abides with data protection laws

What is the ICO?

Information Commisioner's Office, ensures comanies keep to rules and fine those that do not.

What are the six DPA policies?

1. Personal data must be fairly and lawfully processed
2. Personal data must be obtained for specified, explicit and legitimate purposes
3. Personal data must be adequate, relevant and not excessive
4. Personal data must be accurate and up-to-date
5. Personal data must not be kept for longer than is necessary
6. Personal data must be handled in a way that ensures security

What is the right to be forgotten?

An individual can request to remove personal data under certain circumstances (eg. the data is no longer necessary)

What does the IPA do?

Investigatory Powers Act, 2016 - sets rules on use of investigatory powers by the police and security, and intelligence agencies.

What is a computer network?

A group of computers that connect to share information and resources

What are advantages of networks?

File sharing, Hardware sharing, Communication, Roaming access

What are additional advantages of larger networks?

Centralised maintenance and updates, centralised security, user monitoring, levels of access

What are the disadvantages of networks?

Cost (addition equipment needed), management requires technical staff, spread of malware between connected computers, hacking - compromised security

What is a LAN?

Local Area Network, network that is geographically confined to one site.

What is a WAN?

Wide Area Network, network that is spread over a wide geographical area. Communication is done through national telephone infrastructures or via wireless transmission.

What is a client-server network?

Separated computers into status - client or server.

What is a server in the client-server model?

a computer that manages and stores files, provides services to other computers on the network. Control the network, allows other computers to share and communicate.

What is a quality of severs in client-server models?

They need the higher processing power because many other computers connect to them.

What is a client in the client-server model?

a computer that relies on other computers (servers) to provide and manage data. The computer a person uses on a network is a client.

What is a P2P network?

Peer-to-peer, all computers have equal status. All computers are peers, and can access one another's files.

What are P2P networks best suited to?

Best suited to smaller organisations which few computers, where fewer computers require access to files.

What is the NIC?

Network Interface Card, enables a wired network connection between a computer and another networked device

What is the WAP?

Wireless Access Point, connects to a wired network and provides wireless network radio signal for wireless devices to connect to

What does the Switch do?

Enables multiple wired devices to connect, uses packet switching to direct data to the correct device

What is transmission Media?

Carry data signals from one computer to another. Media either wired or wireless.

What are the qualities of fibre optic cable?

Expensive, transmission speed; over 40 tearbits per sec, maximum distance; over 2 km

What are the qualities of twisted copper wire?

Cheap, speed; 1 gigabit per sec, maximum distance; 100 meters

What are Hubs?

a small device that allows wired devices to connect to a network.

What are Routers?

used to send data signals across the internet.

How do routers work?

collect knowledge of available routes to transmit data. They then determine the most suitable route for sending data.

What is the internet?

A worldwide collection of computer networks.

What is the purpose of the internet?

To enable communication on an international scale

Which model is the internet mostly made of?

Client-server

What do web-servers do?

Store and maintain web content, which is downloaded upon request to client computers

What do mail servers do?

Handle web-based email

What do media servers do?

Allow clients to stream music and videos

What is hosting?

The storage of files and data on a web server

What is DNS?

Domain Name Servers, network address of 4 sets of 3 digits is translated to a domain name so the user can remember better

What does the DNS do?

takes the domain name and looks up its equivalent network address. user’s request forwarded to the server that resides at that network address.

What is the cloud?

remotely-accessed storage

What are advantages of cloud storage?

easy access of files, reduced need for backups

What are disadvantages of cloud storage?

no security guarantees, no data back up guarantee, data access limited by access to internet

What is a virtual network?

Network that can securely connect geographically unrelated computers via the internet.

What factors impact network performance?

number of devices in a network, bandwidth of transmission medium, type of network traffic, network latency, number of transmission errors

What does bandwidth mean?

a measure of the amount of data that the medium can transfer over a given period of time

What does latency mean?

a measure of how long it takes a message to travel from one device to another across a network.

What impacts latency?

Latency is affected by the number of devices on the network and the type of connection device.

What are advantages of a star topology?

Each node is separated, a failure in one does not affect other nodes. New nodes can be added to the network, higher performance as message is passed on to its intended recipient only

What are disadvantages of a star topology?

whole network fails if switch fails as no node can communicate, wired star topology requires plenty of cable - in a large network this can be expensive

Where are star toplogies mostly used?

Found in large organisations and home networks

What are the two types of mesh topology?

full mesh, partial mesh

What's the difference between partial and full mesh
networks?

Partial mesh are not connected to all computers, whilst mesh are all connected, partial mesh therefore has fewer routes for a message to travel along

Why are wired mesh networks uncommon?

Connecting all nodes to all other nodes is expensive and impractical.

What are advantages of mesh topologies?

Messages can be received more quickly if the route to the intended recipient is short. Messages should always get through as they have many possible routes on which to travel multiple connections mean (in theory) that no node should be isolated
multiple connections mean each node can transmit to, receive from more than one node at the same time new nodes can be added without interruption or interfering with other nodes

What are disadvantages of mesh topology?

impractical to set up because of the high number of connections needed, many connections require a lot of maintenance

What are protocols?

Rules that govern communication.

What is an IP address?

A unique address for each computer device on a network

What is a MAC address?

Media Access Control, each unique piece of hardware has a MAC address