cs paper 1 Flashcards
(342 cards)
1
Q
What type of data type should be used to store a phone number like 07886756443 and why?
A
string - numeric types would remove the the leading 0
2
Q
Perform an AND mask on the binary numbers: 1010 1101 0101 1011
A
1001
3
Q
What data type stores a collection of characters?
A
string
4
Q
Add the two binary number: 0101 1011 0011 1010 Give answer in decimel
A
149
5
Q
What is the decimal 45 in binary? Give answer as a byte
A
0010 1101
6
Q
What is the hexadecimal number 2E in decimal?
A
46
7
Q
What is the hexadecimal 45 in binary? Give answer as a byte
A
0100 0101
8
Q
Which data type stores True and False?
A
boolean
9
Q
What is -5 in sign and magnitude binary? Give answer as a nybble
A
1101
10
Q
What does the binary 0110 1100 represent in hexadecimal?
A
6C
11
Q
What is the effect of a logical shift left by one place on a binary number?
A
the value doubles
12
Q
What is the two’s compliment binary 1010 1101 in decimal?
A
-83
13
Q
The binary 001101000 0110 is a floating point number with a single-bit sign, 8-bit mantissa and 4-bit exponent. What is the number in decimal?
A
26
14
Q
Perform a logical shift right by two places on the binary number 0110 1010 and convert result to decimal.
A
26.5
15
Q
Perform an XOR mask on the binary numbers: 0101 0101 1011 1011
A
11101110
16
Q
Which of the following is not a character? a. ‘8’ b. R c. % d. 43
A
43
17
Q
The binary 110011000 0011 is a floating point numer with a single-sign, 8-bit mantissa and 4-bit exponent. What is the number in decimal?
A
-3.25
18
Q
What is an array?
A
an ordered, finite set of elements of the same type
19
Q
What type of array is a linear array?
A
a one-dimensional array
20
Q
How can you visualise a two-dimensional array?
A
as a spreadsheet or table
21
Q
How can you visualise a three dimensional array?
A
as a multi-page spreadsheet
22
Q
What is a record also known as?
A
a row in a file
23
Q
What is a record made up of?
A
fields
24
Q
How can you select a field from a record using pseudocode?
A
recordName.FieldName
25
What is the defenition of a list?
a data structure, consisting of a number of items, where the items can occur more than once
26
What are 2 differences between arrays and lists?
1. lists can store data non-coniguously whereas arrays store data in order 2. lists can store multiple data types
27
What is a tuple?
an immutable, ordered set of values of any type
28
What is the difference between a tuple and an array?
tuples are initialised using regular brackets instead of square brackets
29
What is a linked list?
a dynamic data structure, used to store an ordered set of items, in non-contiguous locations
30
What is the name given to the items in a linked list?
nodes
31
What does each item in a linked list contain?
a data field, and an address field called a pointer
32
What is a data field in a linked list?
a field that stores the actual data
33
What is a pointer field in a linked list?
a field that contains the address of the next item in the list
34
What is a graph?
a data structure consisting of a set of nodes connected by edges
35
What is a directed graph?
a graph where the edges can only be traversed in one direction
36
What is an undirected graph?
a graph where the edges can be traversed in both directions
37
What is a weighted graph?
a graph where the edges have a cost to traverse
38
Give 2 ways of representing graphs so that they can be understood by computers.
1. adjacency matrix 2. adjacency list
39
What is an advantage of using an adjacency matrix?
easy to add new nodes
40
What is an advantage of using an adjacency list compared to an adjecency matrix?
space efficient for large sparse networks
41
What is a stack?
a LIFO data structure, where items can only be removed and added to the top of the stack
42
Give 2 examples of where stacks may be used.
1. back buttons on a web page 2. undo buttons
43
What is a queue?
a FIFO data structure, where items are added to the end of the queue and removed from the front of the queue
44
What is a tree?
a data structure which has a root node, and child nodes connected with branches
45
What is a node?
any item in a tree
46
What is an edge?
the connection between two nodes
47
What is the root node?
the node which does not have any incoming edges, at the top of the tree
48
What is a child?
any node which has an incoming edge
49
What is a parent?
any node which has outcoming edges
50
What is a subtree?
a section of a tree which contains a parent and all of the children of the parent
51
What is a leaf?
a node which has no children
52
What is a binary tree?
a type of tree where each node can have a maximum of two children
53
What is a binary tree used for?
to search for values quickly
54
What is a hash table?
an array which is coupled with a hash function
55
What is a collision? (hashing)
where two inputs result in the same hashed value
56
What 2 properties does a good hashing algorithm have?
1. must have a low chance of collision 2. must be fast
57
What is a pre-order traversal?
a traversal algorithm where you traverse the root node, followed by the left subtree then the right subtree
58
What is in-order traversal?
a traversal algorithm where you traverse the left subtree, the root node, then the right subtree
59
What is post-order traversal?
a traversal algorithm where you traverse the left subtree, the right subtree then the root node
60
What does the operation isEmpty() do? (lists)
checks if the list is empty
61
What does the operation append(value) do? (lists)
adds the given value to the end of a list
62
What does the operation remove(value) do? (lists)
it finds the first instance of the given value and removes it from the list
63
What does the operation search(value) do? (lists)
searches for the given value in a list
64
What does the operation length() do? (lists)
returns the length of the list
65
What does the operation index(value) do? (lists)
returns the index of a given value in the list
66
What does the operation insert(position, value) do? (lists)
adds the given value to the given position in the list
67
What does the operation pop() do? (lists)
returns and removes the last value in a list
68
What does pop(position) do? (lists)
returns and removes the value at the given position in the list
69
What does the operation isEmpty() do? (stacks)
checks if a stack is empty
70
What does the operation push(value) do? (stacks)
adds the given value to the top of a stack
71
What does the operation peek() do? (stacks)
returns the value at the top of a stack
72
What does the operation pop() do? (stacks)
returns and removes the value at the top of the stack
73
What does the operation size() do? (stacks)
returns the size of the stack
74
What does the operation isFull() do? (stacks)
checks to see if the stack is full
75
What does the operation enQueue(value) do? (queue)
adds the given value to the end of a queue
76
What does the operation deQueue() do? (queue)
returns and removes the item at the front of a queue
77
What does the operation isEmpty() do? (queue)
checks if a queue is empty
78
What does the operation isFull() do? (queue)
checks if a queue is full
79
What are the 2 De Morgan's laws?
-(A and O) = Ā or Ō
-(A or O) = Ā and Ō
80
What is the purpose of a D-type flip flop?
to store the value of a single bit
81
When is the stored value in a D-type flip flop updated?
on the rising edge of the clock signal
82
What is meant by personal data?
data which can be used to identify a living person
83
Which act concerns the malicious use of computers?
The computer misuse act 1990
84
Which act protects peoples property online?
The copyright, designs and patents act 1988
85
Which act covers the use of personal data?
The data protection act 1998
86
Name the 3 primary offences under the computer misuse act 1990.
1. unauthorised access to computer materials 2. unauthorised modification of computer material 3. unauthorised access with intent to commit further offences
87
Which act covers investigation and surveillance by public bodies?
The regulation of investigatory powers act 2000
88
Which act prevents computer programs from being copied?
The copyright, designs and patents act 1988
89
What name is given to an individual who can be identified with personal data?
data subject
90
What are 3 effects on businesses of computers becoming part of the workforce?
1. higher productivity 2. lower costs of renting 3. lower labour costs
91
What are 3 uses of automated decision-making?
1. driverless cars 2. targeted feed 3. application processes
92
What is the defenition of artificial intelligence?
the ability of a computer to replicate human intelligence, cognitive ability and grasp abstract concepts
93
How do expert systems work? (2 things)
- expert systems consist of a knowledge base made up of facts and rules - this is used to build an inference engine which is interrogated to find diagnosis
94
What are 3 applications of AI?
1. nueral networks 2. driverless cars 3. voice recognition
95
What are 3 negatives of environmental effects of computers?
1. reduced biodiversity 2. greenhouse gases from greater electricity consumption 3. toxic e-waste contaminating water
96
What are 3 ways technology can be used to protect the environment?
1. smart engine designs 2. smart home systems 3.standby features on devices
97
What is the defenition of censorship?
the act of restricting the content that people are able to veiw, publish and access
98
What is the Free Internet?
the idea of an internet where nothing is filtered, in line with the principle of freedom of speech
99
What are 2 ways censorship used within schools?
1. pupils may be prevented from accessing unsuitable material 2. may be used to prevent distractions and maintain high productivity
100
What are 2 arguments in favour of surveillance systems?
Detecting crime
Prevention of crime
101
What is datamining?
the process of analysing large data sets to uncover hidden trends
102
What are 3 things web designers must take into account when designing a website?
1. colour paradigms 2. layout 3. character set
103
What is the ciruit diagram for a full adder?
104
What does the arithmetic and logic unit do?
completes all arithmetic and logic operations
105
What is the control unit?
a part of the processor which directs operations inside the CPU
106
What are registers?
small memory cells that operate at high speeds
107
Where do all the arithmetic, logic or shift operations occur?
in registers
108
What does the program counter (PC) do?
holds the address of the next instruction
109
In which part of the CPU do all calculations take place?
the arithmetic logic unit (ALU)
110
Where are intermediate arithemtic and logic results stored?
accumulator
111
What does the memory address register do?
holds the address of a location that is to be read from or written to
112
What does the memory data register do?
temporarily stores data that has just been read from or data that needs to be written
113
What does the current instruction register do?
holds the current instruction, divided up into opcode and operand
114
What is a bus?
a set of parallel wires connecting two or more components together
115
What is a system bus?
the collection of the data, address and control bus
116
What is the width of a bus?
the number of parallel wires it has
117
What is the data bus?
a bidirectional bus used to transport data and instructions between components
118
What is the control bus?
a bi-direction bus used to transmit control signals betweeen internal and external components
119
What is the address bus used for?
to transmit the memory address, specifying where data is to be read from or written to
120
What does adding a wire to the address bus do to the number of addressable locations?
it doubles the number of addressable locations
121
What does the bus request indicate?
a device is requesting access to the data bus
122
What does bus grant indicate?
the CPU has granted access to the data bus
123
What does memory write do?
causes the data on the data bus to be written into the addressed location
124
What does memory read do?
causes the data from the addressed location to be placed onto the data bus
125
What does the interrupt request control signal indicate?
a device is requesting access to the CPU
126
What is the clock control signal used for?
to synchronise instructions
127
What is assembly language?
a programming language where mnemonics are used to represent instructions
128
What is opcode used for?
to determine the type of instruction and what hardware to use to excecute it
129
What is the operand?
the address of where the operation is performed
130
What occurs during the fetch stage? (4 things)
1. address from the program counter is copied to the memory address register 2. the instruction held at that address is copied to the memory data register 3. simultaneously the contents of the program counter is increased by 1 4. the value of the memory data register is copied to the current instruction register
131
What occurs during the decode stage?
the contents of the CIR is split into opcode and operand
132
What occurs during the excecute phase?
the opcode is executed on the data
133
What is the clock speed?
the number of clock cycles completed per second
134
What is cache memory?
the CPU's onboard memory which can be accessed a lot faster than main memory
135
What is von neumann architecture?
architecture where there is a shared memory and data bus for both data and instructions
136
What is harvard architecture?
architecture where there is a seperate memory and data buses for data and instructions
137
What is contemporary processing? (2 things)
Contemporary processors use a combination of Harvard and Von Neumann architecture. Von Neumann is used when working with data and instructions in main memory, but uses Harvard architecture to divide the cache into instruction cache and data cache.
138
What does RISC stand for?
reduced instruction set computer
139
What does CISC stand for?
complex instruction set computer
140
What is CISC?
a large instruction set
141
Where are CISC instructions built into?
hardware
142
What 2 places is CISC used?
embedded systems microprocessors
143
What is RISC?
a small instruction set
144
What is each instruction in RISC the same as?
one line of machine code
145
Where is RISC used?
everyday devices
146
What is the benefit of RISC processors?
pipelining is possible since each instruction takes one clock cycle
147
Whare are the 2 benefits of using CISC processors?
1. compilers have to do less work 2. they require less RAM, since instructions are smaller
148
What is a graphics processing unit (GPU)?
a co-processor made up of lots of independent parallel processors
149
Whare are 2 uses of GPU's?
1. image processing 2. machine learning
150
What are multi-core systems?
systems where there are multiple cores that seperate fetch-execute cycles
151
What are parallel systems? (2 things)
1. systems where multiple instructions can be completed at any given time 2. they don't require multiple cores and can use threading and pipelining instead
152
What are 3 types of magnetic storage?
1. hard disk drive 2. floppy disk 3. magnetic tape
153
What are 3 examples of input devices?
1. keyboard 2. mouse 3. microphone
154
What is an example of a device which is used for both input and output?
touchscreen
155
What name is given to the areas on a CD's surface, which have been burned into grooves by a laser?
pits
156
What does CD stand for?
compact disk
157
What are 3 examples of output devices?
1. speaker 2. monitor 3. printer
158
What is the order of of capacity for CD, DVD and Blue-ray, in order of increasing capacity?
CD DVD Blu-Ray
159
In a hard disk drive, what is mounted at the end of the actuating arm?
read / write head
160
What storage device has a typical capacity in the range 500GB - 5TB?
hard disk drive
161
What are 2 disadvantages of SSDs?
1. high cost per GB 2. limited number of read/write cycles
162
What does ROM stand for?
read only memory
163
What is the structure where information is stored in flash memory?
information is stored in blocks, which are combined to form pages
164
What is meant by the term non-volatile in storage?
information is not lost when power is lost
165
What 2 type of logic gates are used in flash storage?
NAND and NOR
166
What are 3 advantasges of SSD's?
1. higher transfer speeds 2. lightweight 3. no moving parts
167
Is ROM volatile or non-volatile?
non-volatile
168
Which form of storage devices uses silicon semiconductores to store information?
flash
169
What are 3 disadvantages of CD's?
1. easily damaged by scratches 2. relatively low capacities 3. relatively slow transfer speeds
170
What is an operating system?
a collection of programs that work together, to provide an interface between the user and computer
171
What are 3 functions of an operating system?
1. memory management 2. user interface 3. utility software
172
What is a similarity of paging and segmentation?
both are used when RAM space is insufficient, which can cause disk thrashing
173
What is a difference between paging and segmentation? (2 things)
- paging uses equal sized sections called pages - segmentaiton uses variable sized, logical sections call segments
174
How is virtual memory used when there is not enough RAM? (3 things)
1. a section of the hard drive is used to act as RAM 2. sections of programs not currently being used are temporarily moved into virtual memory through paging 3. freeing up memory for other programs in RAM
175
What is an interrupt?
a signal generated by software or hardware to indicate to the processor that a process needs attention
176
What is the process of the interrupt service routine? (6 steps)
1. interrupt register is checked at the end of each fetch-decode-execute cycle 2. if there is an interrupt that exists with a higher priority compared to the current process, the current contents of the registers in the CPU are transferred into a stack 3. the relevent interrupt service routine is loaded into RAM 4. a flag is set to signal that the ISR has begun and is reset once the ISR has finished 5. the interrupt register is checked again, if there are interrupts of a higher priority, the process is repeated 6. if there are no interrupts with a high priority, the contents of the stack are popped and placed back into the special memory registers
177
Which of these scheduling algorithm are pre-emptive or non pre-emptive? FCFS, SRT, SJF, MLFQ, RR
pre-emptive - RR, SRT, MLFQ non-preemptive - FCFS, SJF
178
What is an advantage of using multilevel feedback queues for scheduling?
services most urgent interrupts first
179
What is a disadvantage of using multilevel feedback queues for scheduling?
hard to implement
180
What is the defenition of a real-time operating system?
real-time operating systems perform a task within a guaranteed time frame
181
Where are real-time operating systems used?
in systems where a response within a given time frame is critical
182
What are the 3 functions of the BIOS when running tests upon computer start up?
1. POST which ensures all hardware is correctly connected and functional 2. checks the CPU clock, memory and processor 3. tests for external memory devices
183
What is the role of a device driver?
to enable the OS to interact with hardware devices
184
What are 3 examples where a virtual machine may be used?
1. testing programs 2. protection from malware 3. running software, compatible with different versions and types of operating systems
185
What is an advantage of intermediate code?
platform independent
186
What is an disadvantage of intermediate code?
slower execution
187
What is the difference between applications and systems software?
applications software is utilised directly by the end-user where as systems software ensures the high performance of the computer
188
What are 3 examples of utilities?
1. compression 2. disk defragmentation 3. antiviris
189
What are 3 advantages of using closed source code?
1. thorough, regular and well-tested updates 2. expert support and user manuals from company 3. high levels of security as it is developed in a professional, controlled environment
190
What are 3 features of open source code?
1. does not require a license to be used 2. can be modified and sold 3. distributed with the source code
191
What is an advantages of using compiled code over interpreted code?
faster to execute
192
What are 3 advantages of using interpreted code over compiled code?
1. it is platform independent 2. runs instantly without having to wait for compilation 3. useful for debugging
193
What is an assembly language? (2 things)
- a low-level language, that almost has a one-to-one relationship with machine code - it is platform specific
194
What are the 4 stages of compilation in order?
1. lexical analysis 2. syntax analysis 3. code generation 4. optimisation
195
What 4 things happen during syntax analysis?
1. tokens are compared to the rules of the programming language 2. syntax errors are identified 3. symbol table is updated with more details 4. semantic field analysis (finding logic errors)
196
What is a similarity between static and dynamic linkers?
they link external modules and libraries to main program
197
What is a difference between static and dynamic linkers?
for static linkers: - library code is copied into the file. - the file size increases for dynamic linkers: - addresses of libraries are included within file. - external updates are automatically fed through to main program
198
What are 3 advantages of using libraries?
1. error- free 2. save time 3. reusable
199
What is the function of a loader?
provided by the OS, a loader retrieves the library or subroutine from the given memory location
200
What are the 3 purposes of the optimation stage of compilation?
1. reduce execution time 2. reduce inefficient sections of code 3. remove redundant code
201
What are the 7 stages of software development? (ADDTIEM)
analysis design development testing implementation evalutation maintenance
202
What is the defenition of white box testing? (3 things)
- a form of testing carried out by software development teams, - where the test plan is based on the internal structure of the program - all of the possible routes through the program are tested
203
What is TELOS?
a method of analysis used by designers to evaluate the feasibility of a project
204
What 5 aspects does TELOS consider? (mneumonic)
technical economic legal operational scheduling
205
What are agile methodologies? (2 things)
- a collection of methodologies, which aim to improve the flexibility of software development - that responds quickly to changes in user requirements
206
What are 3 advantages of waterfall programming?
1. straight forward to manage 2. clear structure 3. clear documentation
207
What are 3 disadvantages of extreme programming methodologies?
1. high cost due to two people working on one project 2. teamwork and good communication is essential 3. end-user must be present during the development of the project
208
What type of projects are spiral programming methodologies suited to?
large, risk-intensive projects with a high budget
209
What type of projects are rapic application (RAD) programming methodologies suited to? (2 things)
- projects where high usibility is required and user requirements may not be clear from the start or are continually changing - suited to projects of a small to medium size with relatively low budget and short time-frame
210
What is the defenition of an algorithm?
a set of instructions used to solve a problem
211
What are 3 key qualities of algorithms?
1. must always reach a stopping condition 2. must be able to deal with invalid inputes 3. must always prodcude a valid output for any defined input
212
What are programming paradigms?
different approaches to using a programming language to solve a problem
213
What are the 2 broad catagories which programming paradigms are split into?
- imperative - declarative
214
What are 2 advantages of procedural programming?
1. can be applied to a wide range of problems 2. relatively easy to write and interpret
215
Whate are 2 uses of declarative programming?
1. expert systems 2. ai
216
What are the 4 main structures used in structured programming?
1. sequence 2. selection 3. iteration 4. recursion
217
How does assembly language differ from machine code? (2 things)
- assembly language uses mnemonics rather than binary - one line in assembly language is equal to one line in machine code
218
What is the function of the STA mnemonic?
to store the value in the accumulator at the given memory address
219
What is the function of the BRP mnemonic? (2 things)
1. to branch to a given address if the value in the accumulator is positive 2. it is a conditional branch
220
What is the function of the opcode? (2 things)
- to specify the instruction to be performed and the addressing mode - the operand holds a value, related to the data on which the instruction is to be performed
221
What are the 4 addressing modes?
direct addressing indirect addressing indexed addressing immediate addressing
222
What is a class? (2 things)
- a template for an object that defines the state and behaviour of an object - on object is an instance of a class
223
What are 2 disadvantages of object orientated languages?
1. requires a different style of thinking, which can be difficult for programmers accustomed to other paradigms to pick up 2. generally unsuitable for smaller problems
224
What name is given to the public and private keys used in asymmetric encryption?
key pair
225
What are the 2 types of compression?
- lossy - lossless
226
Which type of compression is the quality of a file not degreaded?
losless
227
What is the purpose of encryption?
to keep data secure during transmission
228
What are 2 types of lossless compression?
- run length encoding - dictionary encoding
229
Which form of encryption do the sender and reciever share the same private key?
symmetric encryption
230
How many keys are used in asymmetric encryption?
two (one public and one private)
231
If person A wants to send a message to person B using asymmetric encryption which key should they use to encrypt the message?
B's public key as it would only be able to be decrypted with B's private key, which only B has access to
232
What is a collision?
when 2 keys map to the same hash
233
What is run length encoding?
a lossless compression where repeated characters are replaced by one occurrence and the number of time the character is repeated
234
What is hashing?
the process of turning an input into a fixed size value
235
What data structures uses hashing to store information with constant lookup time?
hash table
236
What is compression?
the process of reducing the space required to store a file
237
What are 3 properties of a hashing algorithm?
1. low chance of collision 2. quick to calculate 3. smaller output than input
238
What is HTML?
the language that web pages are written in
239
What does HTML do?
allows a browser to interpret and render a webpage
240
What is a tag in HTML?
values within angle brackets eg
241
What is an identifier selector?
a value that follows a hashtag
242
What is a class selector?
a value that follows a full stop
243
What is CSS?
a language like HTML, but used to describe the style of webpage
244
What are the names of the 2 methods of applying CSS?
- internal CSS - external CSS
245
Where do you write internal CSS?
inside the style tags, directly within the HTML document
246
Where do you write external CSS?
you write it in a seperate document
247
How do you use external CSS in your HTML code?
use the tag
248
What is javascript?
a language used to add interactivity on webpages
249
Is javascript interpreted or compiled?
interpreted
250
What is a search engine?
- a program that searches through a database of internet addresses, looking for a resource based on a criteria set by the user
251
What software does a search engine use?
web crawlers
252
What does a web crawler do?
- travels across the internet collecting keywords and phrases from a web page, and adds it to an index of web rescources
253
What is the pagerank algorithm?
the algorithm used to determine the order, when showing web results for a search engine query
254
What 2 factors determine a page rank?
- the number of incoming links it has from other web pages - the page rank of the web pages that link to it
255
What is server side processing?
when a client sends information to a server for processing
256
What is client side processing?
when information is processed on a local device
257
What is a relational database?
a database that recognises the difference between entities and uses different tables for each entity
258
What is an entity?
an item of interest which information is stored about
259
What is a flat file?
a database that consists of a single file, usually about one entity
260
What is a primary key?
a unique idetifier for each record in a table
261
What is a foreign key?
the attribute which links 2 tables together
262
What is a secondary key?
an index, other than the primary key, used to search and sort through the database with more convenience and speed
263
What is normalisation?
the process of designing the best layout for a relational database
264
What 4 things does normalisation try to accomplish?
1. reduce reduncancy 2. make data consistent throughout linked tables 3. records can be added and removed without issues 4. allows complex queries to be carried out
265
What is an index?
a data structure used to search and access data in a database quickly
266
Is the primary key automatically indexed?
yes
267
What is the defenition of capturing data?
the process of obtaining the information you wish to use
268
What method do banks use to capture data from cheques?
they use MICR to get all of the details apart from the amount which must be entered manually
269
What does selecting data mean?
the process of reducing excess information to obtain only the data you require
270
What does managing the data mean?
manipulating the information in any of way, such as sorting or selecting certain parts using SQL
271
What is the most common language used to manipulate data in databases?
SQL
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What are the requirements to be in first normal form?
there must be no attribute that contains more than a single value in a cell
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What are the 2 requirements to be in second normal form?
- the database is in first normal form - there are no partial dependencies (no composite keys)
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What are the requirements to be in third normal form?
- the database is in second normal form - there are no key dependecies
275
What does SQL stand for?
structured query language
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What is SQL?
a declaritive language used to manipulate databases
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What is referential integrity?
the process of ensuring consistency as it makes sure that information is not removed if it is required elsewhere in a linked database
278
What is a transaction defined as?
a single operation executed on data
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What does ACID stand for?
atomicity consitency isolation durability
280
What does atomicity (in ACID) mean?
a transaction must be processed in its entirety or not at all
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What does consistency (in ACID) mean?
a transaction must maintain referential integrity rules between linked tables
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What does isolation in (ACID) mean?
simultaneous execution of transactions should lead to the same result as if they were executed one after the other
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What does durability (in ACID) mean?
once a transaction has been executed it will remain permanent, regardless of the circumstances
284
What is record locking?
the process of preventing simultaneous access to a record
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What is the name of an issue that can arise as a result of record locking?
deadlock
286
What is redundancy?
the process of creating more than one copy of data in a physically different location
287
What is a network?
2 or more computers connected together, that transmit data
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What is a physical topology?
the physical layout of the network
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What is logical topology?
the topology that describes the flow of data through a network
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What is a bus topology?
topology where all terminals are connected to a backbone cable
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What are 2 advantages of the bus topology?
- cheaper to set up - does not require any additional hardware
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What are 3 disadvantages of the bus topology?
- if backbone cable fails, the entire network is diconnected - as traffic increases, performance decreases - all computer can see data transmission
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What is a star topology?
a network where a central node directs the flow of data, and each terminal is connected to the central node
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What are 3 advantages of the star toplogoy?
- no data collisions - if one cable fails, only that station is affected - data is transmitted faster
295
What are 2 disadvantages of the star topology?
- expensive due to switch and cabling - if the central switch fails, the entire network fails
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What is a mesh topology?
a toplogoy where every node is connected to every other node, most commonly found with wireless technology
297
What are 3 advantages of mesh topology?
- no cabling cost - as the numer of nodes increases, reliability and speed increase - data travels faster as it does not travel through a central switch
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What are 2 disadvantages of the mesh topology?
- need to purchse devices with wireless capabilities - maintaining the network is difficult
299
What are protocols?
a set of rules defining how 2 devices communicate with eachother
300
Why are protocols standard?
so devices from different manufacturers dont have problems communicating
301
What is the structure of the internet?
the internet is a global network of interconnected networks
302
What does TCP stand for?
transmission control protocol
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What does IP stand for?
internet protocol
304
What is the function of the application layer during data transmission?
the application layer specifies what protocols need to be used, to relate the application to what it is being used for
305
What is the 2 roles of the transport layer during data transmission?
- to establish an end-to-end connection between the source and destination computer - to split up data into packets
306
What is the role of the network layer during data transmission?
adds the source and destination IP addresses
307
What is the function of the link layer during packet transmission?
adds the MAC addresses to the packet
308
What does the application layer do when it recieves data?
presents data in the form it was sent
309
What does the transport layer do when it recieves data?
removes the port number and reassembles the packets
310
What does the network layer do when it recieves data?
removes the IP adresses
311
What does the link layer do when it recieves data?
removes the MAC address
312
What is a local area network?
a network spread over a small geographical area or positioned on a single site
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What is a wide area network?
a network spread over a large geographical area, usually requiring extra hardware
314
What does DNS stand for?
domain name system
315
What is DNS?
the name given to the method of naming internet resources (.com, .co.uk etc)
316
What is circuit switching?
the process of creating a direct link between 2 devices and data is transferred the entire duration of the link
317
What is a requirement of circuit switching?
the transfer and download rates must be identical on both devices
318
What is packet switching?
a method of communicating packets of data across a network
319
What are 2 advantages of packet switching?
- there are mulitple methods to arrive at a destination, so if one breaks you can take another route - packets can be transferred over a very large network, such as the internet
320
What is a disadvantage of packet switching?
time is spent deconstructing and reconstrucing packets
321
What are 2 advantages of circuit switching?
- data arrives in a logical order, which results in a quicker reconstruction of data - it enables 2 users to hold a call without any delay in speech
322
What are 2 disadvantages of circuit switching?
- devices must download and transfer at the same rate - switches introduce electrical interference, which can corrupt or destroy data
323
What 4 things does the header of a data packet contain?
1. the source and destination IP address 2. protocols being used 3. order of the packets 4. the time to live limit
324
What does the packet payload contain?
the raw data
325
What does the packet trailer contain?
the checksum or cyclic reduncdancy check
326
What is the purpose of a firewall?
to prevent unauthorised access to a network
327
What 2 things is a firewall made up of?
- 2 network interface cards - firewall sofware
328
What is a proxy?
a web server that acts as an intermediary, collecting and sending data on behalf of a user, protecting their identity
329
What are 3 advantages of using a proxy?
- allows users to remain anonymous - data can be cached, making it faster to load - reduces web traffic
330
What is the function of a network interface card?
to connect a computer to a network
331
What is the function of a switch?
to direct the flow of data across a network, commonly used in star topologies
332
What is the function of a router?
to connect 2 networks together
333
What is the function of a gateway?
to connect 2 networks and translate protocols, so they can communicate without any issues
334
What is client-server networking? (2 things)
- a relationship between terminals (computer) and a single server, - which allows them to communicate and share resources
335
What are 3 advantage of client-server networking?
- increased security - central single backups - data and resources can be shared
336
What are 2 disadvantages of client-server networking?
- expensive to set up - trained staff are required to maintain the network
337
What is peer-to-peer networking?
a network where the terminals are all connected to each other to share resources
338
What are 3 advantages of peer-to-peer networks?
- cheaper to set up - easy to maintain - easy to share resources
339
What are 2 disadvantages of peer-to-peer networks?
- they can be used to contribute towards piracy - each computer has to be backed up independently
340
What are 3 examples of where real-time operating systems are used?
1. self driving cars 2. life support sytems 3. power systems
341
What does POST stand for?
power on self test
342
What does MICR stand for?
magnetic ink character recognition
