IB Computer science Flashcards
1
Q
Hardware
A
<ul><li>Physical parts of a computer</li><li>Includes both internal(RAM+motherboard) and external(keyboards+monitors etc.)</li><li>Internal-<span>components</span></li><li><span>External-</span><span>peripherals</span><br></br></li></ul>
2
Q
Peripherals
A
<ul><li>External device providing input/output</li><li>Communicate with system via device drivers</li></ul>
3
Q
Network
A
<ul><li>Multiple devices that can communicate and share resources with one another via a transmission medium</li><li>2 main networks-<span>LANs </span>and <span>WANs</span></li></ul>
4
Q
<span>Software</span>
A
<ul><li>Computer programs or sets of instructions</li><li>Consists of lines of codes that have been compiled into a program</li></ul>
5
Q
<span>Human resources</span>
A
<ul><li>Describes both people who work for a company/organisation+dept that manages resources for employees</li><li>Known as <span>end-users</span><span> and </span><span>stakeholders</span></li></ul>
6
Q
Client(in networks)
A
<ul><li><span>Accesses services+resources provided by a server</span></li></ul>
7
Q
Server
A
<ul><li>Provides data to other computers and fulfils a client's request</li><li>Software is specific to type of server,but hardware is not important</li></ul>
8
Q
Client server model
A
<ul><li>Each client is connected to a single server</li><li>Clients request connections to the servers</li><li>Can be accepted/rejected</li></ul>
9
Q
Client server model <span>+ves</span>
A
<ul><li>Centralised management of resources</li><li>Backups and network security controlled centrally</li></ul>
10
Q
Client server model <span>-ves</span>
A
<ul><li>High set up and maintenance costs</li><li>Single point of failure</li></ul>
11
Q
DNS server
A
<ul><li>Translates domain names into IP addresses, so they can be accessed by the user</li><li>Sends corresponding IP address of the needed web server back to the user's browser</li></ul>
12
Q
Router
A
<ul><li>Routes data from a LAN to another network</li><li>Receives+forwards data packets</li><li>Determines most efficient path for packet</li></ul>
13
Q
Firewall
A
<ul><li>Acts as a filter protecting a network from incoming and outgoing traffic</li><li>Monitors incoming+outgoing traffic,following set rules</li><li>Hardware/software</li></ul>
14
Q
Social issue
A
<ul><li>Problem that influences a considerable number of individuals </li><li>Includes crime, health,education,media+propaganda etc.<br></br></li></ul>
15
Q
Ethical issue
A
<ul><li>Problem or situation that needs person/organization to choose between options which are considered right/wrong</li><li>Examples include:</li></ul>
-Computer crime<br></br> -Privacy<br></br>
16
Q
Social issues in networks
A
<ul><li>Cyberbullying</li><li>Less face-face interaction</li><li>Addiction</li><li>Hacking</li></ul>
17
Q
Ethical issues in networks
A
<ul><li>Cybercrime</li><li>Identity theft</li><li>Data privacy</li><li>Malware attacks</li></ul>
18
Q
Stakeholder
A
<ul><li>Person,group or organisation that has an interest/concern in an organisation</li></ul>
19
Q
Ask yourself… when identifying stakeholders
A
<ul><li>Who will be affected by new system?</li><li>Who will new system affect?</li><li>Who will the end-users be?</li><li>What are their needs?</li></ul>
20
Q
Methods of obtaining a client’s requirements
A
<ul><li>Surveys</li><li>Interviews</li><li>Direct observation</li><li>Collecting documents</li></ul>
21
Q
Observation
A
<ul><li>Walk around organisation-watching how things are done</li></ul>
22
Q
Observation <span>+ves</span>
A
<ul><li>Information gathered is first-hand + unbiased</li></ul>
23
Q
Observation <span>-ves</span>
A
<ul><li><span>People may act differently than normal when being observed</span><br></br></li></ul>
24
Q
Interviews
A
<ul><li>Interview key members within a system-find out how it works</li></ul>
25
Interviews +ves
- Lots of detailed info can be gathered
- Suggestions for improvements to the system can be heard
26
Interviews -ves
- Takes a long time
27
Questionnaires/surveys
- People are given questionnaires to fill out
28
Surveys +ves
- Large amount of data from large group can be gathered
- Simple
- Little time needed to analyse(if done electronically)
29
Surveys -ves
- Bias possible-info is limited by survey qs
- Quality of responses may be poor/not useful
- Hard to ask the 'right question'
30
Collecting documents
- Look at documents currently being used in the system-find how system works
31
Collecting documents +ves
- Detailed info about current system can be gathered
- Can be seen where old system has problems
32
Collecting documents -ves
- Time consuming
- Documents may be hard to understand(forms/outputs etc.)
33
4 methods before making a new system
- Examine current systems
- Look at competing products
- Literature search
- Organisational capabilities
34
Examine current system steps
- Who does what?
- How do they do that?
35
Organisational abilities steps
- Determine what organisation can manage+do
- Can they afford new equipment?
- Can the staff use new system(do they need training?)?
- Can they have any 'downtime' to upgrade?
36
Competing products
- Observe competitors
- See what is being done/is possible
37
Intellectual property
- Something unique that you physically create
38
Literature search
- Consult literature to see other products
39
Types of diagrams to represent system requirements
- System flow chart
- Data flow diagram
- Structure chart
40
Flowcharts
- Represent algorithms,workflow or processes
- Used to show how processes should work+help figure out how to create a system
41
How do flowcharts help developers?
- Inform decisions that need to be made+ the necessary steps that must be taken
- Estimate development time frames
- Identify who should be involved at each step
- Identify bottlenecks+other problems
42
Input/Output
43
Processing
44
Disk storage (symbol)
45
Online storage (symbol)
46
Document
47
Communication link
48
Data flow
49
Tape
50
Data flow diagram
- Shows flow of data in an information system
51
Entity symbol(data flow)
52
Process symbol(data flow)
53
Data store symbol(data flow)
54
Data flow symbol
55
Entity definition
source and destination of information data.
56
Process(data flow)
Activities and action taken on the data.
57
Data storage(data flow)
When, but not how, data is stored.
58
Structure chart
- Represent organisation of a system,showing different parts in a hierachy
59
Prototype
- Abstract representations of a system,only focusing on one/two aspects
- Important in testing-each component can be tested+idea of system can be illustrated to client
60
Purposes of a prototype
- Fail early and inexpensively
- Gather more accurate requirements-demonstrate functionality of product+help end-users decide what they want in the product
- Technically understand the problem-can see any possible challenges of the design
- File patent
61
Iteration(in design process)
- procedure in which repetition of a sequence of operations yields results successively closer to a desired result
62
Importance of iteration in design process
- Helps you be sure on what needs to be improved
- Improvements in one iteration only possible due to improvements in last iteration
- New technology/techniques can be used
- User's needs can change
- Stability and reliability improves
63
Consequences of not involving end user for the user
- Software is not suitable for intended use-decrease user productivity
- User may be unsatisfied
- Unhappy customers-reduced user productivity
64
Consequences for developer of not consulting end user
- Legal action could be taken against developers
- Decreased reputation
- Loss of market share/breakdown of company
- Harder to get feedback+help from users
65
Why should we listen to the end-user in the design process?
- Understand own needs+situation far better
- Software developer has limited domain knowledge-can't appreciate end users' needs
66
Topics concerning the introduction of new IT systems
- Robots replacing humans
- AI algorithms replacing humans
- New systems are addictive/less efficient
- New systems lead to new markets
67
Usability
- How simple and self-explanatory the use of a system is for inexperienced end-users
68
Ergonomics
- How well the form fits the function
- Discipline concerned with optimising human well being and system performance through the application of theory,principles,data and methods
69
Accessibility
- Ability of the device to meet the needs of as many people as possible
70
Problems with devices
- Difficult to handle hardware
- Complex user interface
- Specialist support needed to use device
- Short battery life
- Small screen size
- Limited storage/portability
- Small text
71
Types of disabilities
- Visual
- Auditory
- Mobility and dexterity
- Cognitive
72
Methods of improving accessibility
- Touch screens
- Voice recognition
- Text-speech
- Braille keyboard
73
Usability issues within a system
- What happens if they can't access system/only certain parts?
- Can't access output?
- Glitches+crashes
- Incompatibility-time formats,currencies
- Interface language problems
74
Moral issue
- Issue with potential to help or harm anyone
75
Economic issue
- Issue concerned with organisation of money,industry and trade etc.
76
Environmental issue
- Problem concerned with protection of the natural world
77
Context definition
- the background, environment, framework, setting or situation surrounding a system
78
What are 2 considerations when considering a new system's context
- The extent of the new system
- The limitations of the new system
79
What are some organisational issues when installing a new system? (1.1.1)
- Software/hardware incompatibility
- User roles / the organisation restructure their workflow
80
Problems with changing a system (1.1.2)
- Users may not like change
- New systems may omit old features
- Expensive
- Old systems may be faster in certain situations
- Data loss during migration
81
Change management steps (1.1.2)
- Plan
- Communicate
- Integrate
- Evaluate
82
Plan (1.1.2)
- Business must first need a clear and valid reason for the change process
83
Communicate (1.1.2)
- Communicating the change to the key stakeholders
84
Integrate (1.1.2)
- Consult the stakeholders before enacting the change process
85
Evaluate (1.1.2)
- Examining the stakeholders' and end-users' response to the change
86
Legacy system definition (1.1.3)
- An old method, technology, computer system or app that is no longer supported or available for purchase anymore
87
Risks with legacy systems (1.1.3)
- More susceptible to security vulnerabilities and malware
- Increased maintenance costs-less hardware and software for the system, lack of IT staff with the skills for that specific system
- Integrating with other systems can be difficult
- Compliance risks-data protection and privacy laws etc.
- Inefficient operations-decreased productivity
88
Merger definition (1.1.3)
A combination of 2 entities or more, into one
89
Issues with mergers (1.1.3)
- Software incompatibility
- Language differences
- Time zone differences
- Workforce cultural differences
90
Local software definition (1.1.4)
- Where the software is installed on a particular computer or set of computers
91
Remote software (1.1.4)
Software that is installed on a server or computer somewhere on the internet to be used via a browser or specific local application
92
SaaS (1.1.4)
- Software distribution model where a third-party provider hosts applications and makes them available to clients over the internet
93
Benefits of SaaS (1.1.4)
- Minimises IT responsibilities and costs
- Useful for small businesses- subscription can be adjusted easily for their specific needs
- Reduction in staff workload-IT workers don't need to perform tasks associated with onsite hardware+software
94
Drawbacks of SaaS
- Companies using multiple SaaS applications or trying to connect them with on site software may experience some integration issues
- Relying on a third party to store your data and business processes
- Businesses must be mindful of compliance regulations regarding storing data in a remote data centre
95
4 methods of implementing/installing a new system (1.1.5)
- Direct changeover
- Parallel running
- Pilot running
- Phased conversion
96
Direct changeover (1.1.5)
- Old system is stopped and new one is started
97
+ves of direct changeover (1.1.5)
- Minimal time and effort
- New system is available immediately
98
-ves of direct changeover (1.1.5)
- No backup if new system fails
99
Parallel running (1.1.5)
- New system is initialised but old system is kept running alongside it
100
+ves of parallel running (1.1.5)
- Backup if new system fails
- Outputs from both can be compared-ensure new one is functioning properly
101
-ves of parallel running (1.1.5)
- Expensive to run 2 systems
102
Pilot running (1.1.5)
- New system is tested using a small part of the organisation
- Once it is running properly and all bugs have been fixed, it is implemented everywhere
103
+ves of pilot running (1.1.5)
- All features are fully tested-any bugs can be found
- If the new system fails only a small part of the organisation suffers
- Staff part of the pilot can train others
104
-ves of pilot running (1.1.5)
- No backup for subset of the organisation in the pilot group if new system fails
105
Phased conversion (1.1.5)
- New system is introduced in phases
106
+ves of phased conversion (1.1.5)
- People can get used to new system
- Staff training can be split into stages
107
-ves of phased conversion (1.1.5)
- No backup for new system
108
Problems arising from data migration (1.1.6)
- Incompatible file formats
- Data structure differences
- Validation rules
- Incomplete data transfers
- International conventions on dates, currencies & character sets
109
Incompatible file formats (1.1.6)
- Same piece of software may have different versions-data from one version may not be compatible with another
110
Data structure differences (1.1.6)
- Data being moved from an array to a linked list etc. can cause problems
111
Validation rules (1.1.6)
- Rules applied to inputs
- If different at destination than at source-data can be rejected and lost
112
Incomplete data transfers (1.1.6)
- Only part of data will be at destination-data loss
113
Differences in data/currency/character set (1.1.6)
- In the UK, 3/5/18 means 3 May 2018, but it means 5 March in the USA
- The $ might mean US dollars, but could be taken to mean Zimbabwe dollars which use the same symbol but is worth significantly less.
- A set of character used in one country, e.g. ﷼ in Saudi-Arabia, might be copied as ?? on Russian computer.
114
Consequences of not running tests (1.1.7)
- System that doesn't work as expected-reduces productivity and end-user satisfaction
- Software may not be appropiate for intended purpose
- Undiscovered bugs in system
- Decrease in organisation's reliability and reputation
115
Static testing (1.1.7)
- Involves verification
- Can include reviews, walkthroughs or inspections
- No execution of code
116
Dynamic testing (1.1.7)
- Involves validation
- Program is executed
- Can be done to test specific parts of the code
117
Alpha testing (1.1.7)
- Performed by internal employees of the organisation
- Done on the developer's site
118
Beta testing (1.1.7)
- Performed by clients/end-users not part of the organisation
- Done at client location
119
Black-box testing (1.1.7)
- Testing software without knowing its internals
- Uses software interfaces
120
White-box testing (1.1.7)
- Looks inside the software
- Uses that knowledge to help with the testing process
121
User acceptance testing (1.1.7)
- Testing any new/updated system with its end users
- Checks if it meets their expectations
122
Automated testing (1.1.7)
- Method in software testing using machines to automatically execute tests and compare the results with the expected ones
- Usually done on large amounts of code
123
User documentation definition (1.1.8)
- Any document that explains how to use the features and functions of a system to its end-users
124
Importance of user documentation (1.1.8)
- Makes users aware of particular features that may not be obvious
- If the documentation is simple-less training needed for users so system implementation is faster
125
Types of user documentation (1.1.9)
- Help files
- Online support
- Printed manuals
126
Help files (1.1.9)
- Files supplied together with the system
127
+ves of help files (1.1.9)
- Accessible any time when using program
- Provide general instructions on how to use system
- General instructions on solving common errors
128
-ves of help files (1.1.9)
- Only can be used after system installation
- Only deal with general errors
- Lack a search capability-have to look through the file for your specific solution
129
Online support (1.1.9)
- Web service hosted by the system's developer to provide user documentation
130
+ves of online support (1.1.9)
- More extensive than help files
- Constantly updated by developers with FAQs
- Often have live support-can talk to a real human operator
- Search capabilities
131
-ves of online support (1.1.9)
- Reliant on internet connection
- Live support can be ineffective with users unfamiliar with computers
132
Printed manuals (1.1.9)
- Manuals printed on paper and supplied with the system
133
+ves of printed manuals (1.1.9)
- Always available
- Help with system installation
- Can be read by users before they work with the system
134
-ves of printed manuals (1.1.9)
- Can be lost/destroyed
- Usually only provides help on system installation
- Rarely updated
135
Importance of user training (1.1.10)
- Productivity is dependent on familiarity with the system
136
Methods of delivering user training (1.1.10)
- Self-instruction
- Formal classes
- Remote training
137
Self instruction (1.1.10)
- Users learn how to use the system on their own
- Usually use a manual or watch a tutorial etc.
138
+ves of self instruction (1.1.10)
- Lowest cost
- Flexible timeline
- Training is specific to exactly what the user wants to learn
139
-ves of self instruction (1.1.10)
- Certain key features may be missed-learning is unstructured
- User may feel overwhelmed without guidance
140
Formal classes (1.1.10)
- Users sit in a classroom listening to an instructor
141
+ves of formal classes (1.1.10)
- Structured learning environment
- Expert on hand to answer questions
- Curriculum covers all aspects
142
-ves of formal classes (1.1.10)
- Expensive
- Rigid schedule+curriculum
- Hardly any personalisation
143
Remote training (1.1.10)
- Instructor training a user or a group of users via a form of remote connection
144
+ves of remote training (1.1.10)
- Structured learning environment
- Expert on hand for questions
- Curriculum covers all aspects
- Flexible locations
145
-ves of remote training (1.1.10)
- Expensive
- Computer based-need basic knowledge to be able to join the meetings etc.
146
Causes of data loss (1.1.11)
- Hardware/system malfunctions
- Human error
- Software corruption
- Malware
- Natural disasters
- Malicious activity of employees or intruders
147
Things to think about when discussing consequences of data loss (1.1.12)
- Can the data be replaced?
- How easy is the data to replace?
- Who will be affected by the data loss?
- Are there financial implications to the data loss?
- Are there ‘life-and-death’ consequences to the loss?
- Who is responsible for data recovery?
148
Methods for data loss prevention (1.1.13)
- Failover system
- Redundancy
- Removable media
- Offsite/online storage
149
Failover system (1.1.13)
- Failover-constant capability to automatically and effortlessly switch to a backup system
150
Redundancy (1.1.13)
- Condition in a database or another data storage technology where data is stored in 2 separate places at once
151
Removable media (1.1.13)
- Use of any storage device that can be removed from a computer while the system is still running
152
Offsite storage (1.1.13)
- Where data or applications are stored in a facility offsite to the organisation or core IT environment
153
Online storage (1.1.13)
- Where cloud storage is used to store data from backups
- Cloud resources and infrastructure can be used to create, edit, manage and restore data along with perform backups
154
Release (1.1.14)
- Process of launching a new product for a specific market or user base
155
Update (1.1.14)
- Software file that contains fixes for problems found by users or developers
- Almost always free
156
Patches (1.1.14)
- Software update where code is inserted into the code of the program
- May:
-Fix a software bug
-Install new drivers
-Address security vulnerabilities
157
How to get updates: (1.1.14)
- Manually
- Automatically
158
+ves and -ves of manual updates (1.1.14)
- Full control
- Time consuming
159
+ves and -ves of auto updates (1.1.14)
- No need to worry about updates
- No control
160
Types of release management (1.1.14)
- Continuous delivery
- Agile software development
- DevOps
161
Continuous delivery (1.1.14)
- Teams produce software in short cycles
- Allows more incremental updates to the application
162
Agile development (1.1.14)
- Requirements of the software evolve through collaboration between end users and cross functional teams within the organisation
- Done in iterations (sprints)
163
DevOps (1.1.14)
- Aims to unify software development and operation
- Utilises lots of automation
- Monitors each step of the software construction
164
Network definition
- Group of computer systems and nodes linked together via transmission media to allow for communication and resource sharing
165
LAN characteristics
- Local Area Network
- Uses MAC addresses and switches
- Private infrastructure
- Usually almost always use Ethernet protocol
166
WAN characteristics
- Wide Area Network
- IP addresses and routers
- Public infrastructure
- Collection of other networks
167
VLAN characteristics
- Virtual Local Area Network
- Group of nodes that appear to be on the same LAN despite not being geographically in the same area
- Software implemented
- Able to quickly adapt to changes in the network requirements
168
SAN
- Storage Area Network
- Secure high speed data transfer network
- Allows access to a centralised storage system
- Allows multiple servers to access a network of storage devices
169
WLAN
- Wireless Local Area Network
- Network that uses radio-waves and usually an access point to the internet
- Allows the users to have mobility
170
Internet
- Uses TCP/IP protocols for data transmission
- network of networks
- Global communication system
- Both hardware and infrastructure
171
Intranet
- Private LAN that cannot be accessed remotely(only can be accessed via VPN or on the organisation's premises)
172
Extranet
- Intranet that can only be accessed remotely via authentication
- Utilised to allow 3rd parties to gain information without granting access to the entire network
173
VPN
- Virtual Private Network
- Uses the internet
- Allows people to access a network remotely but encrypts the connection
- Data is transmitted through a secure pathway known as a tunnel-tunnelling
174
PAN
- Personal Area Network
- A network covering a very small area
- Bluetooth etc.
175
P2P
- Peer to Peer network
- Network model where nodes are connected directly to one another
- Directly exchange files and resources etc.
176
Network standards definition
- Rules followed by manufacturers of network hardware to ensure interoperability between devices
177
Importance of standards
- Allows devices to be compatible and communicate with each other
- Helps ensure data transmission is secure-minimum latency and good integrity of data
- Allows manufacturers to have a framework on which to build their system
178
2 types of network layer models
- OSI Network layer-7 layers
- TCP/IP Network layer-4 layers
179
+ves of layers
- New protocols can be added to each layer easily
- Change to one layer doesn't affect functionality of another layer
- Similar protocols can be grouped into layers with a specific function in data transmission
180
OSI Model layers
- 7 -Application
- 6-Presentation
- 5-Session
- 4-Transport
- 3-Network
- 2-Data link
- 1-Physical
181
TCP/IP model layers
- Application
- Transport
- Network
- Link
182
Function of application layer in TCP/IP model
- Collects data to be transmitted
183
Function of transport layer in TCP/IP model
- Breaks up data into packets
- Adds packet sequence number
- Adds checksum
184
Function of network layer in TCP/IP model
- Adds IP addresses of the sender and receiver node
185
Function of the link layer in TCP/IP model
- Adds MAC addresses of sender+receiver node
- Physically transmits data as bits
186
Comparison of TCP/IP and OSI model layers
187
What 2 main technologies does a VPN use?
- Encryption
- Tunnelling
188
VPN encryption
- Converting plaintext to ciphertext via a private key
- Need a decryption key to understand the data
- Computers at each end of the tunnel encrypt incoming data and decrypt it at the other end
189
VPN tunnelling
- Tunnel-secure pathway through the public network
- On this connection packets are constructed via the specific VPN protocol format and sent privately over public networks via encapsulation
190
VPN components
- Client VPN software
- VPN infrastructure
- VPN server
191
VPN infrastructure characteristics
- Need to use specific VPN-routers and firewalls which allow legitimate VPN traffic to pass through
192
VPN server characteristics
- Handles and manages incoming VPN traffic
- Establishes and manages VPN sessions and their access to network resources
193
+ves of telecommuting
- Improved productivity
- Reduced costs for businesses and employees
- Flexibility for the employees
- No need to commute to work
- Less environmental impact
194
-ves of telecommuting
- Social isolation
- Lack of expertise or support on certain issues
- Need specific hardware and a network connection etc.
- May be more distractions in a home environment
195
+ves of VPN
- Allow for telecommuting
- Improves data security-encryption and tunnelling
- Bypass geo restricted content via masking IP addresses
196
-ves of VPN
- Reliability of VPN is controlled by ISP
- Not all VPNs are compatible with products
- May lead to increased latency on the user's connection if the nearest VPN server is very far
197
Protocol definition
- Set of rules for data communication over a network
198
Data packet definition
- Small unit of data that is used in network communication
199
3 components of a data packet?
- Header
- Payload
- Trailer
200
What is contained in the packet header?
- IP address of sender and receiver
- MAC address of sender and receiver
- Sequence number
201
What is contained in the packet payload?
- Actual data block
202
What is contained in the packet trailer?
- Check Sum
- Parity Bit
203
Key functions of protocols
- Maintain data integrity
- Manage flow control
- Prevent deadlock
- Manage congestion
- Error checking
204
Data integrity definition
- The overall completeness,accuracy and consistency of the data
205
Flow control
- Mechanism which ensures the rate at which data is being transmitted is in proportion with the receiver's receiving capabilities
- Ensures receiving node is not overwhelmed with data
206
Congestion control
- Congestion-where a node or link carries so much data network service quality deteriorates
- This leads to queuing delay,frame or data packet loss and new connections unable to be made
207
Error checking
- Techniques used to detect noise or other impairments introduced to data during transmission
- Utilises parity bits and checksums
208
Deadlock
- Where 2 nodes/processes are trying to access the same node at once-neither is able to proceed
- Relevant protocol needs to stop and re-queue them
209
Primary factors affecting speed of data transmission
- Traffic
- Number of users
210
Secondary causes affecting speed of data transmission
- Time of day
- Distance
- Infrastructure
- Type of cabling
211
Tertiary factors affecting speed of data transmission
- Environmental issues(temperature etc.)
- Infrastructure limitations due to financial reasons
- Type of data being transmitted
212
Compression definition
- Encoding data to use fewer bits than the original version
213
Lossless v lossy compression
214
Uses of compression
- Backups/archiving
- File transfer
- Media file transfer over the web
- Encryption/protection
215
Backups/archiving (compression)
- Compressed data is smaller in size than original file-saves storage space
216
File transfering (compression)
- Fewer bits transferred per second-faster transmission rates
- Lower bandwidth needed for uploads and downloads
217
Encryption/protection (compression)
- Compressing files scrambles their data adding an extra layer of protection against any hackers etc
- Reduces amount of data needing to be encrypted
218
4 characteristics of transmission media
- Security
- Reliability
- Cost
- Speed
219
UTP-Unshielded Twisted Pair cables characteristics
- Security-moderate if encrypted
- Susceptible to EMI
- Relatively cheap
- Relatively fast(faster than radiowaves)
220
Fibre optic cables
- Security-very secure
- Generally quite fragile(glass)
- Very expensive
- Fastest transmission media
221
Radio waves
- Security-insecure unless encryption is used
- Susceptible to interference
- Technically free
- Quite slow speeds
222
Packet switching definition
- Routing data packets through a network depending on the destination address contained in each packet
223
Packet switching steps
- Data is broken up into packets
- Routed from source to destination using switches and routers
- The most efficient routes for the packets are found via the MAC and IP addresses in the header
- Reassembled at destination using sequence number
- Checked for errors using checksum
- If any packets are missing data is retransmitted
224
+ves of wireless networks
- Radiowaves are technically free
- No need for cabling
- Global standards
- Minimal set up costs
- Allows for user mobility
225
-ves of wireless networks
- Interference
- Limited range
- WAPs can be used to steal data
- Transfer speeds are slower than wired networks
- Each WAP only has a finite amount of bandwidth
226
Hardware components in a wireless network
- Nodes
- Wireless NIC
- Radio waves
- Connection point(WAP etc)
227
Software components of a wireless network
- Network Operating System (with drivers)
- Protocol stack
- Applications
228
Types of wireless networks
- WiFi
- Wimax
- 3G
- LTE
229
Wi-Fi (Wireless Fidelity)
- Also known as WLAN
- Most commonly used for home networks
- Backwards compatible with most older Wi-Fi standards
- Relatively slow to quick data transmission
230
WiMAX
- Worldwide Interoperability for Microwave Access
- Large distance internet connections
- Relatively cheap
231
3G (Third Generation)
- Primary way mobile phones access the internet today
- Allows tunnelling of phone lines
- Relatively fast
232
Key factors concerning security
- Confidentiality
- Integrity
- Availability
233
Why is system security difficult ?
- Users
- 'Arms race'-constantly evolving malware etc.
- Systems may have a weak point which can cause it to collapse
234
One factor authentication
- Something you know-password etc.
235
2 factor authentication
- Something you have
- OTP etc.
236
3 factor authentication
- Something you are
- Biometrics etc.
237
Firewalls
- Hardware or software or combo of both
- Analyses data packets based on predetermined rules
- Acts as a filter monitoring incoming and outgoing network traffic
238
MAC Address filtering
- Hard-coded into devices by manufacturers
- Can be used to identify specific pieces of hardware
- Routers can keep track of allowed and banned MAC addresses
239
Physical security examples
- Locks on doors
- Security personnel
- Reinforced rooms
- Barbed wire fences
240
Encryption in wireless networks
- Using algorithms to convert plaintext into ciphertext, so that it cannot be understood by any hackers
- 3 main standards-WEP,WPA,WPA2
241
WEP
- Wireless Equivalent Privacy
- Very quickly broken and replaced by WPA
242
WPA and WPA2
- WPA-intrusions could still occur from outside the network
- WPA2-intrusion can only occur by those who have accessed the network previously
243
+ves of userID
- Access rights can be set for each user
- User groups can be created-manage access rights in batches
244
-ves of userID
- userIDs can be stolen
- System can be bypassed
- No protection against interception
245
+ves of encryption
- Strong encryption is very difficult to break
- Maintains confidentiality of data
- Data is encrypted so even if transmission media is insecure, data is still secure
246
-ves of encryption
- Hard to encode-need specialists
- Computationally expensive
- Some encryption methods may have built in backdoors
247
+ves of MAC filtering
- Another layer of security
248
-ves of MAC filtering
- Danger of whitelist being discovered, so MAC addresses can then be spoofed
- Difficult to manage whitelist
- Doesn't help against data interception
249
+ves of firewalls
- Effectively prevents unauthorised access to a network
250
-ves of firewalls
- May slow the network
- Issues with censorship on a software firewall
251
What does RAM do? (6.1.1)
- Memory which stores currently running programs and data being used.
252
Effect on system if RAM is too limited (6.1.1)
- Part of secondary storage needs to be used as virtual memory (much slower than RAM)
- Less processes can be executed simultaneously
- If virtual memory is not available, programs or data won't load
253
What does secondary storage do (6.1.1.)
- Permanent storage of data and programs including vital programs such as OS
- Non-volatile
254
Effect on system if secondary storage is too limited (6.1.1)
- May not be enough space to permanently store programs and data-data loss occurs
- Not enough space available to use virtual memory
- Less data can be stored on the system in general
255
What does the processor speed do (6.1.1)
- Processor performs all calculations and instructions in a system
- Speed - measurement of how many instructions executed per second
256
Effect on system if processor speed is too limited (6.1.1)
- Processor takes longer to perform tasks
257
What cores do (6.1.1)
- Each processor has at least one core (ALU) which performs arithmetic and logic operations
258
Effect on system if cores are limited (6.1.1)
- Without multiple cores, tasks cannot be executed simultaneously
- More cores=more tasks executed simultaneously
259
What is screen resolution (6.1.1)
- Measurement of the number of pixels in the height x width of a display
260
Effect on system if resolution is too limited (6.1.1)
- Number of pixels displayed is lower-pixelated display
- Poorer quality images but also smaller file size
261
What does a sound processor do? (6.1.1)
- Helps the system with sound reproduction and processing-frees up CPU
- Also may contain bank of sampled sounds-helps to produce better quality audio
262
Effect on system if sound processor is too limited (6.1.1)
- CPU has to help with processing sounds-reduces system performance
- Overall quality of audio is not as high without use of sound processor
263
What does a graphics processor do (6.1.1)
- Complex graphics processing-3D rendering etc.
264
Effect on system if graphics processor is too limited (6.1.1)
- CPU is less efficient at graphics processing-lower quality or slower
265
What does cache do ? (6.1.1)
- Stores instructions and data most likely to be requested next by the CPU from the RAM
- CPU doesn't need to wait for instruction or data to arrive all the way from RAM
266
Effect on system is cache is too limited (6.1.1)
- CPU will have to wait longer for instructions/data to be fetched from RAM, decreasing performance
- Less cache hits
- Slower processing of common tasks on the system
267
What is bandwidth (6.1.1)
- Measurement of the amount of data able to be sent at the same time in a certain time frame
268
Effect on system if bandwidth is too limited (6.1.1)
- Lower data transmission speeds from one point to another-slower network performance
- Takes longer to process data in its entirety
269
What is network connectivity (6.1.1)
- The type of network connection being used within a network
270
Effect on system if network connectivity is limited (6.1.1)
- Reduced data transmission speeds, and higher latency
- Possibly more interference and transmission errors depending on the type of connection
- Lower download and upload speeds
271
Mainframes:Processor, primary and second memory
- Contains thousands of cores
- Vast amounts of primary and secondary memory
272
Common uses of mainframes
- Virtualise smaller computers
- Weather/financial models and predictions
273
Servers and server farms:Processor,primary and secondary memory
- Many high spec PCs running in parallel
- Vast amounts of primary memory (less than mainframes, more than PCs) along with secondary memory
274
Common uses of servers and server farms
- Serve networks
- Data centres for cloud storage
- Online data backups
275
Desktop PCs: Processor,memory
- Single processor, but multiple cores
- Quite a lot of primary ( less than servers) and secondary memory (much less than servers)
- Upgradeable
276
Common uses of desktop PCs
- Companies and schools with no need for portability
- Gaming
277
Sub-laptop (netbooks): processor and memory
- Single or low multi-core
- Limited RAM
- Quite little secondary storage,usually a SSD
278
Common uses of sub-laptops
- Personal computing devices
279
Cell phones/mobiles: processor, memory
- Single or multi-core
- Moderate RAM
- Quite limited secondary storage
- Constrained by screen size along with input options
280
Common uses of cell phones
- Personal computing devices
281
Tablets: processor,memory
- Single or multi-core
- Not much RAM
- Moderate secondary storage(less than PC)
- Very portable
282
Common uses of tablets
- Media consumption
- Personal computing device
283
PDAs:processor,memory
- Single core
- Very limited RAM and secondary storage
284
Common uses of PDAs
- Not used that much anymore
- Calendars/emails
- Delivery drivers
285
Digital camera:processor,memory
- Single core
- Limited secondary and primary memory,however secondary storage is expandable
286
Common uses of digital camera
- Higher end photography
287
Think about consequences on a system of limiting which 5 things ?
- Primary memory
- Secondary storage
- CPU speed
- CPU cores
- Connectivity
288
Questions to think about and their consequence to the user (6.1.4)
If the processor is too slow?
If the processor has only one core?
If the amount of primary memory is limited?
If the amount of cache is limited?
If network connectivity is limited?
If user access is limited to a single user per device?
If the processor has only one core?
If the amount of primary memory is limited?
If the amount of cache is limited?
If network connectivity is limited?
If user access is limited to a single user per device?
289
Multi-user system definition
- Many users on the same machine or many users connected to the same network
290
Multi-programming system definition
- System that can have different programs installed
291
Single programming system
- Can only run one program/set of programs
292
4 main functions of the OS (6.1.5)
- Device configuration
- File management
- Memory management
- Interface platform
293
How does device configuration work with the OS? (6.1.5)
- OS uses device drivers (software program that acts as a translator) to allow the system to communicate with peripherals
294
How does managing primary memory work with the OS (6.1.5)
- OS ensures each process runs in its own allocated memory space
- Therefore OS allocates and deallocates memory
- Prevents overwriting
- Ensures a program has sufficient memory to run
295
Virtual memory management with the OS (6.1.5)
- Virtual memory is part of the secondary storage that is used as RAM when RAM is full
- Virtual memory is transferred in the form of pages
- Data from RAM is temporarily transferred to secondary storage
296
Managing secondary storage with the OS (6.1.5)
- Provides structure and access methods for the storage
- Known as folder-structure
- OS manages security access of these folders and files also
297
Providing an interface with the OS (6.1.5)
- User gives commands to computer and enters data
- OS translates I/O and sends it to correct memory or folder address to be processed
- Provides link between user and computer hardware
298
Time slicing
- Multi-user system-time slice is set amount of processing time each user gets
- Single user system-time slice is set amount of processing time each program gets
- Allocating a fixed period of time to each process for which they are allowed to run
- CPU time is allocated dependent on time and priority
299
Interrupt handling (6.1.5)
- Function of the OS which is executed when an interrupt is detected
- Interrupt-signal to processor emitted by hardware/software indicated an event needs immediate attention
300
Security management with the OS
- Utilises authentication and access rights
- In multi user systems OS also isolates each users tasks, data and programs along with controlling access rights to specific parts of memory and secondary storage
301
Parallel processing with the OS (6.1.5)
- Multi-core systems
- Utilises prioritising where highest priority tasks are executed until a higher priority task appears
- Scheduler sorts tasks into order of priority
302
Main resource management techniques (6.1.7)
- Scheduling
- Policies and mechanisms
- Multitasking
- Virtual memory
- Interrupt
- Polling
303
Scheduling (6.1.7)
- Action of deciding which processes can occur when and for how long
- Allocating CPU time amongst running programs and tasks
304
Policies (6.1.7)
- Policies-what is to be done
- Mechanism-how it is to be done
- Policies are rules followed by the system in order for it to run as effectively and safely as possible
305
Multi-tasking (6.1.7)
- The OS allows more than one program or task to be executed simultaneously on a system
- OS keeps track of the progress of each of these tasks and allows you to move from one to another without any loss of information
306
Virtual memory + paging (6.1.7)
- Feature of the OS where secondary storage is used as an extension to RAM
- Involves transferring pages from RAM to VM when you are running many programs or large ones
- OS is constantly swapping data between the 2 locations
- OS will transfer back pages they need from VM and then send other pages to the VM so there is space for these needed pages
- Memory manager determines this by sending the least-used page usually to VM
307
Interrupt (6.1.7)
- Signal emitted by hardware or software indicating an event needs immediate attention
- OS responds first suspending its current activities,saving these tasks then execute an interrupt handler
- After interrupt handler is finished the system resumes its previous activities
308
Polling (6.1.7)
- Process of where OS regularly checks another device or peripheral in order to see its status(ready or not)
- Often done with low-level hardware
309
Dedicated OS definition (6.1.8)
- OS designed for a specific device or purpose
310
+ves of a dedicated OS (6.1.8)
- Higher level of security-developers can restrict possible entry methods for malware etc.
- Can be customised for maximum speed and efficiency for whatever specific device or purpose it is being used for
- Since you know the purpose and hardware for the OS, developers can eliminate elements of a typical OS which may not be needed in this scenario(less resource usage)
311
Abstraction (6.1.9)
- In general, it is omitting the unnecessary and complex info in a system
- In OSs certain hardware details may be hidden and higher-level functions may be provided
312
Drive letters (6.1.9)
- Single A-Z letter assigned to a physical drive or drive partition in a system
- Example of abstraction
313
Virtual memory (example of abstraction) (6.1.9)
- OS handles paging in the optimal manner to maximise performance, we can just alter settings of virtual memory
314
Java virtual machine (6.1.9)
- Interprets compiled Java binary code for a computer's processor
- Each platform has its own JVM
315
Control system definition
- Device/set of devices that manages,commands or regulates the behaviour of other devices or systems
316
2 main types of control systems
- Open-loop control systems
- Closed-loop control systems
317
Key features of an open-loop control system
- Non-feedback system(output has no impact on control action of input)
- No self correction of errors
318
Examples of open loop control systems
- Toaster
- Electric hand dryer
- Automatic washing machine
319
Key features of a closed loop system
- Utilises feedback-output can influence control action of input
- Output is measured to be compared with input
- Self correction can then occur based on the output
320
Examples of closed loop systems
- Air conditioner
- Centralised heating system
321
Main steps in control systems operation cycle
1. Analogue inputs taken from the sensors
2.Analogue data converted to digital using ADC
3.Digital data is processed by the microprocessor and digital output generated
4.Digital data converted to analogue using DAC
5.Output executed using actuators
2.Analogue data converted to digital using ADC
3.Digital data is processed by the microprocessor and digital output generated
4.Digital data converted to analogue using DAC
5.Output executed using actuators
322
Automated doors features (example of control system)
323
Heating system (example of control system)
324
Microprocessor definition
- Computer system that contains all the functions of a CPU
325
Sensor definition
- A device that converts a physical stimulus into a readable output
326
Actuators function
- Part of a device or machine that helps it with physical movement
- Converts energy into mechanical force
327
Accessibility input devices examples
- Adapted keyboard
- Bigger keys
- Ergonomic(help with Carpal Tunnel Syndrome)
- Adapted mouse,trackball and joystick
- Ergonomic mouse
- Xbox Adaptive Controller(large buttons+is affordable)
- USB mouse with a large trackball
328
Assistive technology examples
- Screen readers
- Screen magnification software
- Alternative input devices
- Motion/eye tracking
- Head pointers
- Speech input software
329
Medical sensors examples
- Airflow sensor
- Body temp sensor
- Accelerometer
- Electrocardiogram sensor
330
Transducers definition
- A device which converts signals from analogue to digital and vice versa
331
+ves of transducers
- Compatible with microprocessors and computers
- Ease of convertibility between analogue and digital
- Remote controllability
332
What is feedback?
- Modification or control of a process or system by its results or effects
333
Examples of processes that use feedback
- Missile tracking moving target
- A heating system in a house
- Auto-pilot
334
Embedded system definition
- A computer system within another mechanical or electrical device with a specific purpose
335
Tagging prisoners-arguments for:
- Allows non-dangerous criminals to move
- Reduces number of people needed to be in prison
- Allows for tracking at all times
336
Tagging prisoners-against
- Could be hacked to track innocent people
- Tracking data could be sold to make money
- Loss of freedom of movement
337
Surveillance
- Monitoring/observation from a distance using electrical equipment
338
Arguments for surveillance
- Greater security
- Can be used as evidence in court cases
- Fewer people need to monitor others-physical security replaced by cameras etc.
339
Arguments against surveillance
- Loss of privacy
- Could be hacked and used for malicious purposes
- Utilised to spy on people
340
CCTV-how it works
- Video surveillance technique
- Works independently to monitor a certain area
341
Arguments for CCTV
- Reduces crime-deterrent
- Cost effective solution to criminal damage
- People may feel safer
342
Arguments against CCTV
- Doesn't stop crime
- Expensive to install and maintain
- May be used for illegal spying
343
What is a centralised control system?
- Control system where all processing occurs at a single, central location such as a microprocessor
- Microprocessor controls numerous terminals (sensors/actuators)
344
What is a distributed control system?
- Control system where multiple decentralised microprocessors control multiple sensors and actuators
- These terminals all communicate with one another via a network
345
+ves of centrally controlled systems
- Easier to maintain-everything is managed centrally
- More control
- Cheaper-just need one microprocessor
346
+ves of distributed systems
- Quicker access
- Sharing of tasks and resources
- No single point of failure
- Response will be more specific to environment
347
-ves of centrally controlled systems
- Single point of failure
- Slower processing-single processor has to manage all terminals and respond to all sensors etc
- Actuators will be less responsive to their environments
348
-ves of distributed systems
- Much more expensive-multiple microprocessors and sensors
- Much more complex-harder to maintain
- Harder to fix any potential errors
349
What is an autonomous agent?
- Software entity that carries out a set of operations on behalf of a user or another program with some degree of independence
350
4 key features of an autonomous agent
- A-autonomy
- B-reactive behaviour
- C-concurrency/sociality
- D-persistence
351
Autonomy key features
- Self activation-agents don't need to be triggered to perform a task
- No human intervention-agents can select task themselves without human intervention
352
Reactive behaviour key features
- Agent senses environment it is in (use of sensors) and decides what to do
353
Concurrency/sociality key features
- Agents able to interact with other agents through communication in various modes
- Include coordination,cooperation and competition
354
Persistence key features
- Code describing an agent runs continuously like a process
- Not executed on demand
