Paper 1 Flashcards

1
Q

Bitwise XORing…

A

toggles a subset of the bits in the value

when you use a 1 the bianry is toggled/ switched around and 0s there is no impact

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2
Q

Depth First algorithm

A
  1. PUSH the first node onto the stack
  2. Repeat:
    a. push each node onto the stack until a child node is reached
    b. visit the node which is the lowest you can reach
    c. if no node to visit pop off the stack
  3. Until stack is empty
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3
Q

Encryption

A

Encryption is the process of encoding a message so that it can be read only by the sender and the intended recipient.

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4
Q

serialisation

A

Serialisation ensures that transactions do not overlap in time and therefore cannot interfere with each other or lead to updates being lost

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5
Q

Class

A

a template to set out a define what attributes an object of a certain type should have

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6
Q

how is redundancy used usefully

A

organisations build in redundancy e.g. duplicate hardware so that if the main system fails the backup can take over

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7
Q

X∧X=

A

X

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8
Q

do until loop pseudocode

A

do
code
until
condition

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9
Q

Sequence

A

do one statement after another in the correct order

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10
Q

Symmetric Encryption

A

Symmetric Encryption is when the same key is used to encrypt and decrypt the message. Both party’s must know the key and also keep it secret.

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11
Q

NOT

A

reverses the outcome of the expression

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12
Q

Byte Scale

A

bit, nibble, byte, kilobyte, mega, giga, tera, peta, exa, zetta, yotta

Multiple by 1024 to move up

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13
Q

Method of capturing data (Manual)

A

Paper data capture form (read by OCR & OMR or typed in manually)

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14
Q

purpose of operating systems: managing external devices

A

Using device drivers to translate operating system instructions into those understood by specific models of hardware device

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15
Q

How are character sets used to represent text?

A

When character in the set has a corresponding binary value which is a set number of bits. These are stored in a sequence that represents a word etc.

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16
Q

Capacity of magnetic

A

640 GB - 1TB

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17
Q

clock use

A

synchronise the change of state of flip flop circuits

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18
Q

linked lists

A

A list of data together with a set of links to sort the data. Data is stored in the order its input and pointers are used to link the data into the desired order.

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19
Q

Selection

A

do a set of statements based on conditions allow your code to make choices- otherwise known as branching

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20
Q

Peer-to-Peer Networking

A

No central computer, all computers are connected to each other locally or over a WAN

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21
Q

disadvantages of Client-Server

A
  • Can be expensive to set up and to manage

- Server is single point of failure

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22
Q

how to convert floating point binary to denary

A

1) First work out the denary number in the exponent which tells us that the binary point moves ‘n’ places to the right
2) Write out a new binary weighting line with the point in the right place and then convert into denary

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23
Q

components of a packet

A

senders address, recievers address, packet contents, sequence number

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24
Q

Consistency

A

Any change in the database must retain the overall state of the database.

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25
clock
sequential circuit that changes state at regular time intervals
26
Program Counter
stores the address of the next instruction
27
POST acronym
Power of self test
28
X∧0=
0
29
relationships
one-to-one one-to-many many-to-many
30
in two's complement the sign is stored in
the most significant bit
31
direct addressing
where the operand contains the address of the value to be used.
32
preorder dot
left
33
Asymmetric Encryption
Asymmetric Encryption (Public Key Cryptography) is when a public key and a private key is used. The public key is used to encrypt the data and the private key is used to decrypt the data. If you use person X’s public key to encrypt the data only person X’s private key will be able to decrypt it
34
Advantages of networks
- allows sharing of data - allows collaberative working - good for communication - allows sharing of resources e.g. printers, storage and scanners - easy to backup to a central point
35
Real-time Operating system
Designed to carry out actions within a guaranteed amount of time even when left running for long period.
36
software
program code. Sequences of instructions which are executed in order to perform a task.
37
Client side processing
data is processed on client side and send back to the server. This is used for security as it avoids data transfers.
38
Disadvantages of the agile model
- Not suitable for quick projects
39
Current instruction register
stores the actual instruction that is being decoded
40
if/else Pseudocode
``` if condition then code elseif condition then code else code endif ```
41
dynamic
size of the structure can change at runtime
42
Optical storage advantages
Cheap light weight and portable Resilient
43
Trace Tables
As you follow code you note down when each variable changes and what each value is
44
structured
the data is organised in a logical way
45
purpose of operating systems: managing the memory
allocating and managing the memory used and relinquished by processes using pages and segmentation. Managing virtual memory
46
constructor of a superclass
public procedure new(inputs) super.new(inputs) attribute = input endprocedure
47
instruction set
a group of instructions that a computer can carry out. unique for computers.
48
code optimisation
(stages of compilation stage 4) the code is optimised to run as fast as possible by removing redundant code (removing variables and procedures that have been written but never called)
49
Multiple cores
Multiple CPUs working on a single computer
50
Pre-emptive
Once a process has entered the running state it can be stopped
51
Inheritance OO pseudocode
``` class Dog inherits Pet code endclass ```
52
Address Bus
A one directional bus that transmits memory addresses that are used as operands in programming instructions, so that data can be retrieved from main memory
53
XML (eXstensible Markup Language)
A markup language that uses tags to denote data
54
Methods of sending data
Electronic Data Interchange (EDI) - is the computer-to-computer exchange of business documents in a standard electronic format between business partners. Application Programming Interface (API) - a prewritten set of subroutines that provide access to the companies data - A URL to a file
55
CISC
Complex instruction set computing, large number of instruction each taking multiple machine cycles to carry out.
56
Clock signal
used to synchronise operations
57
font size CSS property
font-size
58
Uses of real-time operating systems
Airline control, theatre bookings, heart monitors, production lines, radar systems
59
purpose of operating systems: providing networking
communication through protocols and other machines and devices
60
Durability
Once a change has been made to a database it must not be lost due to a system failure.
61
wildcard
*, selects all the elements
62
Tuples
are lists that cannot be edited, they are immutable
63
Hash tables
an array which is coupled together with a hash function.
64
stack data structure
A stack is known as a LIFO, a single pointer is used to point to the top item of the stack, when a new item is pushed onto the stack the pointer is incremented. When an item is popped off the stack the pointer decrements to point to the new top of the stack.
65
second normal form
1. Check the data is already in 1NF 2. Remove any partial dependencies 3. ‘fix’ any many to many relationships you discover
66
Open Systems Interconnection 7 layer model
(7) Application Layer (6) Presentation Layer (5) Session Layer (4) Transport Layer (3) Networking Layer (2) Data Link Layer (1) Physical Layer
67
Query SQL
SELECT * FROM tblName WHERE conditions
68
stepwise approach
breaking down a problem into smaller sections
69
Server side processing
used to interact with permanent storage like databases or files. It also renders the pages to the client
70
sequential files
where the order of data is maintained
71
how to do CSS in HTML

72
Data Protection Act parts
Data processed fairly and lawfully Data should only be collected for specific purposes Data should be relevant and not excessive Data should be accurate and up to date Data should not be kept longer than needed The user has a right to access and correct data The organisation must have suitable security Data can not be transferred outside the UK to any country with no data protection laws
73
How is a stack used in a ISR
when an interrupt comes the current instruction is pushed onto the stack. Once the interrupt has finished it pops the instruction off the stack and processes it
74
OR (+)
75
protecting agaisnt hacking:
- Packet snifferes | - User access logs
76
Attribute
variables contained within and associated to an object
77
BIOS
checks that the hardware is connected is connected and working in what is known as a power on self test
78
polling
The CPU checks with each device if it needs attention. Inefficient and wastes time as some devices will not want attention when called upon
79
how does arithmetic (signed) right shift work?
shift everything to the right and backfill the space with 1s
80
normalising a positive binary number
back fill with 0s
81
Input device examples
``` Key board Card readers Microphones Cameras Barcode scanners OMR/OCR Mice Sensors Magnetic stripe reader touch pads ```
82
Object Orientated language
coders develop a solution which consists of objects that have been modelled on the real worl.
83
sparse graph
A graph which has few edges in relation to vertices
84
Solid-State Storage
uses flash memory so data is read and written directly to blocks and pages on the silicon micro-chips
85
graph
a set of edges/arcs connecting vertices/nodes
86
linking a css/javaScript file
87
Link Layer
(4) Passes data to the physical network
88
Hashing Databases
transforms a string of characters in a record into a shortened form that can be used as a disk address
89
De Morgan's Law
¬ (A∨B) = (¬ A) ∧(¬ B) | NOT (A OR B) is the same as (NOT A) AND (NOT B)
90
Foot Mouse
press key/click button with their foot to send signal.
91
Secondary key
any field in a database which is not a primary, candidate or foreign key. They are used to order queries.
92
Bitwise manipulation
bitwise shifts and masks
93
Bytecode
An intermediate representation which combines compiling and interpreting and is run by a byte code interpreter
94
multi-dimensional arrays
an array containing one or more arrays.
95
Advantages of Using encapsulation
- reduces chance of error - consistent changes - prevents accidental changes
96
word
equal units of memory. each with separate memory addresses.
97
fragmented disk
over time a disk becomes fragmented as old files are deleted and new files are added, free space often becomes scattered across a disk and a program has to be split and spread across a disk to fit. The more fragmented the slower the computer performs
98
procedure
a self-contained set of commands that can be called from different parts of the program.
99
Algorithm for insertion into a binary tree:
1. If tree is empty enter data item at root and stop; Current node = root 2. Else repeat: a. If new data item is less than value at current node go left, else go right. b. Current node = node reach (null if no node) c. Until current node is null 3. Create new node and enter data
100
different traversal methods
preorder inorder postorder
101
Coacial Copper Cables
older, slower and cheaper
102
node at the top of the tree
root node
103
Chip Multi Processor (CMP)
a single chip which contains 2 or more independent CPUs which can execute independent instructions
104
border width CSS property
border-width
105
factors to consider when choosing applications (9)
``` speed does it provide the necessary functionality cost and pricing hardware requirements memory convenience is it well used, tried and tested is it available off the shelf or will it have to be hand written ```
106
TCP/IP stack
Application Layer Transport Layer Internet layer Link Layer
107
Execute
The appropriate instruction/ opcode is carried out on the data/ operand
108
Artificial intelligence
writing software and algorithms which appear to behave as if they were intelligent
109
What is a more complex data type called?
composite types
110
Star topology disadvantages
Can be expensive to set up because of the length of cable required Central device is a point of failure
111
Uses of assymetric encryption
used for transfering data e.g. online shopping
112
basic Boolean operators
AND OR NOT
113
all attributes are dependent on..
the key, the whole key, and nothing but the key
114
height CSS property
height
115
Peer-to-Peer Model:
all terminals have equal status and there is no powerful central server, each computer acts as both a client and a server.
116
distributed computing
when each computer on a network takes on part of a problem
117
SMTP
Simple Mail Transfer Protocol – used by mail servers and clients to transfer email across the internet
118
Software interrupts
illegal instruction encountered Arithmetic overflow new log-on request
119
Uses of CISC
what most desktops use, Intel or AMD
120
Benefits of circuit switching
- highly reliable | - once the circuit is set up communication is fast and generally error free
121
Drawbacks of circuit switching
- dedicated connection therefore even if the channel is free it cannot be used to transmit other data - inefficient - requires more bandwidth - time is taken to determine the physical link before hand
122
Puff/Suck Switch
blow/suck to send signal.
123
Buffer almost empty
buffer allows each device or process to operate without being held up by the other
124
NIC
receive and send electrical signals in a network.
125
partial key dependency
one or more f the attributes depends on only part of the primary key (if the primary key is a composite key)
126
Data Integrity
Data integrity is the maintenance and consistency of data in a data store. The data store must reflect the reality that it represents.
127
internal storage examples
magnetic hard drive, ROM, RAM, internal solid state drive
128
Use of distributed operating systems
Data centres, large companies, weather/financial modelling, data mining trend finding
129
Output device examples
``` speakers plotters printers monitors actuators projectors LEDs ```
130
Static
the size of the structure cannot change at run time
131
indexed addressing
The value given is added to the valued stored in the index register to give the memory location.
132
What does a bitwise left shift do?
multiplies the number by 2.
133
Binary -> denary negative exponent
- exponent
134
create an instance of a class OO
objectName = new className(parameters)
135
Breadth first algorithm
1. PUSH the first node into the queue 2. mark as visited 3. REPEAT: a. visit all unvisited nodes connected to the first node b. push nodes onto the queue 4. until all nodes visited 5. REPEAT: a. POP next node from queue b. REPEAT: i. visit unvisited nodes connected to current node ii. PUSH nodes onto quue c. until all nodes visited 6. until queue empty
136
Absorbtion Law OR
``` A∧(A∨B)=A X AND (X OR Y) is the same as X ```
137
procedural languages examples
Pascal, C, Basic and Python
138
What is ASCII
- A character set - Maps values to characters - Uses 7-bits/ 8-bits per character
139
types of interrupts
- hardware - software - Input/output
140
A∧ ¬A =
0
141
Contemporary processor architectures
Modern high-performance CPU chips incorporate aspects of both Von Neumann and Harvard architectures e.g. memory for both data and instructions but cache is divided into instruction and data and multiple parallel data buses
142
Sign magnitude most significant bit
represents + or - + = negative - = positive
143
Hashing
Hashing is the process used to transform a data item into something different. A hashing function provides a mapping between an arbitrary length input and a fixed length output. It is a one-way transformation meaning you cannot get back to the original form.
144
Memory read signal
causes data from the addressed location in RAM to be placed on the data bus
145
Bus request signal
indicates that the CPU has granted access to the data bus
146
polymorphism
when something appears in multiple forms and the program makes sure the correct meaning of a function is run
147
Inserting an item in a hash table:
1. Feed in key to the hash function 2. Go directly to the array index (HashValue) 3. If the location is empty then insert the value 4. Else follow the linked list in sequence until a free space in found and insert the value
148
opcode
the actual instruction
149
0.1
positive
150
Open Source Software
any software which is supplied along with its original source code. e.g. Linux
151
\
integer division
152
Drawbacks of closed source software
- costs money, can be expensive | - small range of versions of software
153
purpose of operating systems: managing security
servicing and denying requests to access the resources connected to the computer
154
Bottleneck address bus
the width of the address bus determines the maximum possible capacity of the system
155
Input devices for limited mobility
- Foot mouse/pedal - Camera/eye tracker - Microphone - Puff/suck switch
156
Lists
an ordered data structure accessed through an index. the have no predefined scope and can be edited during run time.
157
anchor tag
158
Lossy Compression
Actual data is removed from the file in order to reduce its size. An algorithm is used to strip out the least important data. The original file cannot be restored as data is physically removed.
159
serial file
store data with no specific order meaning if data is added it is simply appended onto the end of the file. You cannot delete data from a serial file. good for storing simple data sets text files and configuration files.
160
commutation LAW OR
A∨B = B∨A | The order in which two variables are OR’ed makes no difference
161
purpose of operating systems: managing the processor
deciding which process to execute next and handling interrupts to the currently executing process
162
Half adder use
adds two bits
163
commutation LAW AND
A∧B = B∧A | The order in which two variables are AND’ed makes no difference
164
end instruction
HLT
165
Binary -> denary positive exponent
+ exponent ->
166
Packet Switching
the data to be transmitted is broke up into individual packets at the source computer. each packet is labelled with an address and sequence number. The packet is then forwarded onto the network and follows its own individual route. Depending on network traffic each packet will take different routes at different times to reach their destination where is is then reassembled.
167
Address bus average width
32 bits
168
normalising a negative binary number
back fill with 1s at the high end and 0s at the low end
169
Possible uses of graphs:
1. Navigation Systems 2. Data Transmission 3. Web page links 4. Social media trends
170
Disadvantages of extreme programming
- Not suitable for programmers separated geographically | - Client must be able to commit to having full time contact with the programmers
171
programming paradigm
a way to classify programming languages based on their features.
172
how to solve hash table collisions
- store the key in in the next available space OR - combine with a linked list
173
Data redundancy
The unnecessary duplication of data in a database
174

paragraph text
175
capacity of solid state
around 500 MB
176
Uses of virtual machines
- used on networks to avoid redundant processors - translating code (Java) - running different operating systems
177
Mesh Topology
an arrangement where ever node is connected to every other node.
178
Memory Data register (MDR)
stores the data which is to be sent or fetched from memory
179
normalising: | moving the point to the left
+ exponent
180
relationship between high-level and assembly code
one to many
181
uses of a GPU
``` Will be present on a graphics card in a computer used in - Machine learning - Oil exploration - Image processing - Financial transactions ```
182
virtual storage disadvantages
Expensive if you want to store large amounts of data | Access times can be slow if there is poor internet connection
183
Cop Right Design and Patents Act
protects the intellectual property rights of individuals and organisations. This law makes it illegal to Copy, Modify or Distribute any software or any other intellectual property without permission of the original creator.
184
post order dot
right
185
    ordered list
    186
    Paired Programming
    one programmer types and another checks at the same time.
    187
    border style CSS property
    border-style
    188
    Transmission media
    the wires that connect a network
    189
    system software
    operates, controls and maintain the computer and its components.
    190
    Bitwise ANDing ...
    extracts a subset of the bits in a value when the mask is a 1 it retains the value however when the mask is a 0 it outputs just 0s meaning only certain values are extracted.
    191
    main factors effecting CPU performance
    clock speed number of cores amount and type of cache
    192
    ACID
    Atomicity Consistency Isolation Durability
    193
    What do the nodes on a binary tree contain
    left pointer, data, right pointer
    194
    CDPA year
    1988
    195
    Disadvantages of the spiral model
    - Acknowledge user input - Create prototypes to communicate to the user ideas better - Better for small projects - Simple
    196
    general purpose application software
    A software that can be used for many purposes e.g. word-processor
    197
    FIFO
    first in first out
    198
    digraphs
    has one or more edges that have an arrow indicating you can only go in one direction
    199
    Internet
    many interconnected networks over many different countries via dedicated connections known as backbones
    200
    Embedded Operating Systems
    embedded systems are often run on dedicated hardware so they run with maximum efficiency, with low powered processors and minimal memory
    201
    Switches
    devices used to connect devices on a network, they use the physical hardware MAC address to send data on to the required destination node.
    202
    Output device
    any device which is able to take data which is stored in a digital form and convert it into another format which wee can process e.g. sound, images or vibrations
    203
    drawbacks of assymmetric
    - not as fast
    204
    MOD
    gives the remainder of a division
    205
    three main class sections:
    class name attributes methods
    206
    Record Locking
    Recording Locking prevents simultaneous access to objects in a database in order to prevent updates being lost or inconsistencies in the data arising.
    207
    Multi-tasking operating system
    one processor is scheduled so that each process receives a very small time slice of processor time giving the impression of them running simultaneously.
    208
    API
    Application Programming Interface governs how two applications should interact
    209
    Adding data from linked lists:
    1. Store the data at the location indicated by the free storage pointer 2. Alter the free storage pointer to the next free storage space 3. Work out where in the list the new item should be inserted 4. Set the pointer for the item that will precede it to the new data item 5. Update the pointer for the new data item to that previously stored in the item the preceded it
    210
    5 most common primitive data types
    integers, real (float), characters, string and Boolean
    211
    Removing data from linked lists:
    1. If the item to remove is in the first position a. Then update starting pointer value of item you want to delete b. Update all the pointers 2. Else if the item is in any other position a. Update the pointer value in the preceding node from the one you want to delete to the value of the pointer in the item to be removed 3. Update the free pointers
    212
    mutable
    structure and data can be changed at runtime
    213
    what connects different networks?
    routers and gateways
    214
    Disadvantages of client side processing
    - Not all browsers support all script | - Because the scripts are processed by the client, they are dependent on the performance of the clients’ machine
    215
    Utility software
    small programs each with a very specific purpose, which is normally concerned with the maintenance and wellbeing of a computer system
    216
    CSS identifier
    HASHTAG #menu{ background-color: #A2441B; }
    217
    for loop pseudocode
    for i=0 to 7 print(“Hello”) next i
    218
    deadlock
    when both users try and access the database at the exact same time meaning neither can edit it
    219
    The text that will appear in the tab heading
    220
    linker (static linking)
    includes links to any library code and place it in a single executable file. this is known as static linking and results in large programs because all the code is held in one file.
    221
    Extreme Programming
    - A type of agile methodology, involving a user imbedded in the company to give feedback. - This results in high quality code being developed quicker.
    222
    exponent
    positive of the binary point is fixed on the number line
    223
    What loads the OS into RAM
    the bootloader
    224
    Buffer
    a region of a physical memory storage used to temporarily store data while it is being moved from one place to another
    225
    purpose of operating systems: providing a platform for Software and utility programs
    provides a framework for applications to run, allowing the to, for example, open and close files easily. The user can also interact with operating systems to manage files and use a range of utilities
    226
    token
    a keyword, constant, variable, identifier or operator from the code
    227
    arcs on a tree
    branches
    228
    Relational Database
    A relational database has more than one related table. It is more efficient that a flat file database as no data is duplicated meaning querying is easier.
    229
    uses of functions and procedures
    breaking a problem into manageable sections | preventing duplicating sections of code when it is needed more than once in a program
    230
    Operating system (System software)
    allows the user to control the computer with ease. Provides a virtual machine hiding the true complexity of the computer from the user. Manages and controls access to the computer's resources.
    231
    normalising a number
    means that there is only one way to represent the number
    232
    virtual storage advantages
    data can be accessed anywhere so long as you have internet access data can be easily shared between devices without having to copy the data and transport it the capacity is limitless
    233
    Operating System Roles
    - Provides a user interface - manages security - provides a platform for utilities/applications - manages external devices - managing the processor/scheduling - managing memory - provides a platform for networking - managing hardware
    234
    bootloader program
    loads the operating system kernel into memory. Stored in ROM
    235
    Where is the waterfall life cycle model used?
    Used in manufacturing industry
    236
    Over-riding
    when the method in the subclass shares the same method as further up in the object tree. the over-ridden method takes precedence and replaces the method further up the object tree
    237
    Characteristics of Procedural
    instructions, sequences, selections, interaction, procedures and functions
    238
    clock
    a device that generates a timing signal which changes at a regular frequency. Its used to synchronise communication between the components of the CPU and the rest of the computer system.
    239
    Cache memory
    Special high speed memory used by a computer. Stores frequently used data and instructions.
    240
    interrupts
    A device sends a signal on the control bus to show the CPU it needs attention
    241
    Unicode
    character set which displays over a million characters
    242
    scheduler
    manages which process to execute next and how much time is allowed to execute a process
    243
    What are character sets needed for?
    needed so that a document which is made on one computer is still readable on another computer. Computers can have more than one character set installed.
    244
    Hardware
    the physical component oft he computer system.
    245
    Microphone
    Make sound to send signal
    246
    advantages of using an external css file
    code only needed to be added to one file but the changes are applied to all the pages that use that css file
    247
    program branch reason
    occurs due to an if statement, function, procedure call or loop.
    248
    primitive data type
    a basic data type provided by the programming language as a basic building block
    249
    array
    allows you to store multiple items of the same data type under a shared common name
    250
    Data mining
    automated process which looks at large sets of data and tries to identify patterns in order to predict something
    251
    different types of operating system
    ``` Distributed Embedded Multi-tasking Multi-User Real-time ```
    252
    Hash function
    code which takes in data called a key and outputs a hash value which is is used to find a fixed index in a hash table
    253
    interpreter
    takes one line of high level source code and converts it directly into machine code then runs it. this has a one to many relationship and is useful for debugging code however the security is bad and the code is executed slowly
    254
    CPU vs GPU
    CPUs excel at doing complex instructions on small data sets whereas GPUs excel at simple manipulations to much larger data sets
    255
    Cloud Computing
    Client-Server network via the internet, where files are kept on a remote server and accessed virtually
    256
    What does the DMBS provide
    ``` Security backups index updating enforcement of referential integrity facilities to update and query the database ```
    257
    client side processing
    Client Processing is where webpages use JavaScript to validate data before it gets sent to the sever for further validation.
    258
    Association LAW (OR)
    ``` A∨(B∨C)=(A∨B)∨C= A∨B∨C A OR (B OR C) is the same as (A OR B) OR C is the same as A OR B OR C ```
    259
    Solid-State examples
    USB pens and SD cards
    260
    advantages of peer-to-peer
    - cheap to set up and maintain | - easy sharing
    261
    Algorithm for deletion into a stack:
    1. Check to see if the stack is empty 2. If the stack is empty report an error and stop 3. Copy the data item in location pointed to by the stack pointer 4. Decrement the stack pointer
    262
    conjunction
    AND
    263
    Atomicity
    a change to a database is either completely performed or not performed at all. A half-completed change MUST NOT be saved back to the database.
    264
    integer
    any positive or negative whole number e.g. 3, 0, -14
    265
    how to normalise a number:
    1. see how many places the binary point has to move so the number starts 01 or 10 2. store this number in the exponent and then new format of the number in the exponen
    266
    Fibre Optic Cables
    newer, faster and high-capacity
    267
    Code generation
    (stages of compilation stage 3) | the syntax tree is converted into object code
    268
    Advantages of a client-server network
    - Security is better since all files are stored in a central location - Back ups are done centrally so individual users do not need to back up - data and resources can be shared
    269
    Algorithm for insertion into a queue:
    1. Check to see is the queue is full 2. If the queue is full report an error ad stop 3. Insert new data item into location pointed to by the head pointer 4. Increment the head pointer and stop
    270
    Hardware interrupt
    - shut down triggered by user pressing on/off button - memory parity error (when comparisons don't match) - internal clock triggers suspending a running process
    271
    why is manageable code important
    easy to read, debug and easy to maintain
    272
    logic gates in a half adder
    XOR (to the sum) | AND (to the carry)
    273
    application layer
    (1) Packages data and passes it on to the transport layer.
    274
    Object Orientated languages examples
    C++ and Java
    275
    The Computer Misuse Act
    makes unauthorized access to computer systems illegal: | The intent to commit or facilitate commission of further offences with intent to impair the operating of a computer
    276
    virtual memory
    when the main memory is almost full sections which are less frequently used are stored on the hard disk to free up RAM space
    277
    first normal form
    1. Eliminate duplicate columns 2. Get rid of any groups of repeating data 3. Identify the primary key 4. Separate out any attributes which are not atomic into separate attributes
    278
    Solid-state storage disadvantages
    Expensive | limited lifespan - each section can only be written to a set number of times
    279
    Operating System
    software that manages the computer; it manages the hardware, software, security and the user interface
    280
    LIFO
    last in first out
    281
    what happens when a search engine indexes a page
    crawlers traverse the web following links and checking each word in the document. It adds an index entry for the page alongside the words position on the page.
    282
    three types of secondary storage
    magnetic, optical, solid-state
    283
    Method of capturing data (Automated)
    barcode readers, scanners, sensors, magnetic ink character recognition, smart card readers
    284
    4 types of system software
    OS, utility, libraries, translators
    285
    JPEG
    joint photographic experts group, losy compressed form of graphics storage
    286
    X∨0 =
    X
    287
    SQL
    SQL is a language which allows for fast, efficient querying and reporting of vast amounts of data held in a relational database. It is a very high-level language.
    288
    Referential Integrity
    Referential Integrity is where table relationships must always be consistent. Any foreign key field must agree with the primary key that is referenced by the foreign key. Thus, any changes to the primary key field must be applied to all foreign keys in another table, or not at all.
    289
    Pre-emtive Algorithms
    based on priority so if one instruction is executing it can be stopped for another instruction to start processing
    290
    Dictionary Coding
    Dictionary coding is when an index is built where every data item in the file is recorded along with an indexed reference. The final compressed file will just consist of the dictionary index along with the sequence of occurrences needed to recreate the original file.
    291
    more bits in the mantissa...
    improves the accuracy but reduces the range
    292
    RISC
    reduced instruction set computing. Small Instruction set where each instruction is performed in one clock cycle.
    293
    magnetic storage positives
    cheap large capacity
    294
    OR
    if both inputs are true or one input is true the the output is true else the output is false
    295
    Advantages of the waterfall model
    - Everyone on the project is very clear on their responsibilities at each stage. - Simplicity - Easy to see if programming is running to schedule
    296
    limitations of half adders
    - can only add one bit numbers | - only two inputs, the carry from a previous addition can't be incorperated
    297
    Atomic
    data is in its lowest level of detail and cannot be split into separate attributes
    298
    Malicous Software
    is software that annoys users or damages their data. For example, Worms, Viruses, Trojans, Spyware and ransomware.
    299
    XML
    extensible markup language, text based means of describing data.
    300
    types of application software (12)
    ``` word processors desktop publishing programs spreadsheets database management Slideshow and presentation Multimedia and video editing photo and graphics manipulation communications, chat and IM social networking email clients web browsers Gaming ```
    301
    real (floating point)
    a positive or negative number with a fractional component e.g. 0.002 or -1.98
    302
    CISC advantage
    simpler software more likely to have a single instruction to carry out an action, larger instruction sets works better with more intensive tasks
    303
    Data integrity is the state of data being
    as intended and accurate
    304
    disadvantages of peer-to-peer
    - no central backing up - slower performance - bad security
    305
    CSS identifiers vs classes
    and identifier can only be used once on one element but classes can be used on multiple elements
    306
    SIMD
    (parallel processing, single instruction multiple data) a single processor carries out an instruction on multiple data
    307
    GPU uses
    graphics, gaming, AI(machine learning), data analysis
    308
    Multi-User Operating System
    Allows multiple users to use the system and its resources simultaneously.
    309
    Drawbacks of packet switching
    - protocols are complex and expensive - packets may be lost - not neccessarily secure
    310
    Variable
    a name refer to a particular memory location that is used to store data. The value of the data held in that memory location is not known when the program is written and can change while the program is running
    311
    Serialisation
    Serialisation ensures that transactions do not overlap in time and therefore cannot interfere with each other or lead to updates being lost
    312
    ASCII
    American Standard Code for Information Interchange
    313
    three categories of programming languages
    procedural Object Orientated Assembly
    314
    X∨¬X=
    1
    315
    Proxies
    A proxy ensures there is no direct physical connection between a single user and a remote source.
    316
    disadvantage of server side processing
    - can be slow | - pages have to be refreshed often to keep up to date
    317
    Hubs
    connects nodes together by broadcasting a signal to all possible destinations. The correct destination will accept the signal
    318
    Association LAW (AND)
    ``` A∧(B∧C)=(A∧B)∧C= A∧B∧C A AND (B AND C) is the same as (A AND B) AND C is the same as A AND B AND C ```
    319
    difference between paging and segmentation
    pages are a fixed size, segments are different sizes pages are made to fit sections of memory, segments are complete sections of programs pages are physical divisions, segments are logical divisions
    320
    Embedded operating systems
    Washing machines, vending machines, car engine systems, traffic lights, pay and display machines
    321
    Star Topology
    an arrangement where a central node or hub provides a common connection point for all other nodes.
    322
    what does security keeping data safe from?
    - accidental or deliberate loss | - malicious access
    323
    Bus Topology Disadvantages
    Main cable is a single point of failure Limited cable length Performance degrades with heavy use Poor security
    324
    What does the width of the address bus determine
    the maximum possible memory addresses of the system
    325
    Lossless Compression
    Reduces the file size but allows the original data be perfectly reconstructed from the compressed data. Actual data is still removed however the data is encoded in such a way that the original can be recreated. Less effect at reducing file size than lossy.
    326
    drawbacks of open source software
    - can be less user friendly/less easy to use - less support available - people may exploit failures maliciously before they are fixed
    327
    Shortest job first (SJF)
    Jobs are sorted in the ready queue according the estimated processor time needed
    328
    advantages of client side processing
    - Allows for more interactivity by immediately responding to a users' action - Removes potentially unnecessary processing from the server
    329
    Ring topology
    an arrangement where on node is connect to two others to form and ring.
    330
    tree
    a simple connected graph with no cycles
    331
    Primary key
    A field that uniquely identifies each record
    332
    Secondary Key
    Any field which isn't a primary/composite key which can help make a query more efficient
    333
    Disadvantages of rapid application development
    - doesn't scale well
    334
    Searching an item in a hash table:
    1. Feed the key to the hash function 2. Go directly to array index (HashValue) 3. If the value is equal to the value that you’re searching for then output the value 4. Else follow the linked list in sequence until you find the value and output the value
    335
    Input instruction
    INP
    336
    1.0
    negative
    337
    Data Bus
    A bi-directional path for moving data and instructions between system components
    338
    GPU
    Graphical processing unit. | used for rendering graphics and processing many parallel streams of data at the same time.
    339
    uses of linked lists
    1. Implementing undo functionality 2. Dealing with browser cache 3. Helping with operating system job queues
    340
    store instruction
    STA
    341
    RIPA Grants rights to:
    - Demand ISPs provide access to a customer's surveillance - Demand ISPs fit equipment to facilitate surveillance - Demand access be granted to protected information - Prevent existence of such interception activities being revealed in court
    342
    program branch result
    the next instruction held in the PC is not carried out
    343
    pipelining
    overlapping stages in the fetch-execute cycle. | fetching the next instruction while the first instruction is being decoded
    344
    example of input AND output device
    touch screen or games controllers
    345
    Embedded Operating Systems
    a computer system that forms part of a device such as a washing machine or car
    346
    Harvard architecture
    - instructions and data are stored in separate memory units - instructions and data are each served by their own buses - allows for pipelining
    347
    CMA year
    1990
    348
    Composite Key
    A unique identifier made from different fields
    349
    positives of databases?
    - provide security - provide automatic backup - enforce data integrity rules - control data redundancy - provide users with controlled access to data they need
    350
    Superclass
    the original class and its code
    351
    pipelining advantages
    improves efficiency
    352
    combine rows from multiple rows
    JOIN
    353
    What does a bitwise right shift do?
    divides the number by 2.
    354
    Overflow
    If the result of a binary addition is greater than 255, an overflow error occurs, where the most significant bit requires a ninth bit (Put it in brackets)
    355
    negatives of multiple cores
    ``` complicated circuitry (more expensive) doesn't always improve performance ```
    356
    by changing the position of the binary point you can...
    increase the size of the number | increase the accuracy of the number
    357
    MIMD
    multiple instruction multiple data, multiple instructions are carried out on multiple data using multiple cores
    358
    Local Area Network (LAN):
    method of connecting computers together in a small geographical area. All the hardware and infrastructure is owned by the business/ organisation that uses it.
    359
    Benefits of Open source software
    - usually free - users are free to amend the source code and tailor the program to their needs - not constrained by commercial considerations - many people are continuously finding and fixing bugs
    360
    instantiation
    the process of creating an object from a class template
    361
    Uses of Multi-tasking operating systems
    desktops and smart phones
    362
    Entity Relationship Modelling
    when the relationships between tables are shown in abstracted view.
    363
    CISC disadvantages
    ``` more complex circuitry/hardware Single machine instruction takes multiple machine cycles to carry out greater energy consumtion can't support pipelining more silicon require to make physically larger in size ```
    364
    How does Java use virtual machine?
    the virtual machine execute intermediate code (Java Byte code)
    365
    Half adder outputs/inputs
    inputs: the two bits to be added outputs: the result and the carry
    366
    Algorithm for deletion/reading from a queue:
    1. Check to see if the queue is empty 2. If the queue is empty report an error and stop 3. Copy data item in location pointed to by the tail pointer. 4. Increment tail pointer and stop
    367
    Writing an alert box
    alert(“Hello World”);
    368
    Search engine indexing
    Uses web crawlers and relies of databases of indexes, and uses those indexes to find more databases forming links
    369
    divides the page into segments allowing for improved styling
    370
    input device
    any device which allows you to get information from the outside world into a computer system so that it can be stored in a digital form
    371
    utility programs examples
    - Disk defragmenter - Automatic backup - Automatic updating - Virus checker - Compression software
    372
    Input/output interrupt
    - Buffer almost empty | - Signals the completions of data transfer between devices
    373
    X∨X=
    X
    374
    First come first serve (FCFS)
    the processes are executed in the order they arrived | if all the processes take along time all the others must wait
    375
    how does the PC know where to return to in the previously executing program after services an interrupt
    by putting instructions on a stack
    376
    how to use a form tag
    377
    changing the contents of an HTML element JavaScript
    chosenElement = document.getElementById(“example”); chosenElement.innerHTML = “Hello World”;
    378
    writing directly to a document JavaScript
    document.write(“Hello World”);
    379
    Benefits of packet switching
    - efficient use of the network - can be rerouted to avoid problems in the network - data is transmitted immediately
    380
    JavaScript Clientside
    Used to process data on clients computer which allows erroneous data validation on client side which is quicker and relieving on a server side.
    381
    Normalisation
    Organising the attributes and relations of a relational database to minimise redundancy
    382
    Firewalls
    a program that blocks unauthorised access onto a network by inspecting packets to find the port they are attempting to access through. If the port is blocked then the packet is rejected.
    383
    Flip flop
    elemental sequential logic circuit that can store one bit and flip between two states
    384
    Server side processing
    data is processed on server side as they can process bigger amounts and take the strain off clients
    385
    Encryption
    A method of transforming data into an unintelligible way so that it cannot be read by unauthorised individuals.
    386
    Advantages of rapid application development
    - flexible to changes - quick - simple - can reduce risk
    387
    Input/ Output interrupts
    buffer nearly empty | signal the completion of data transfer to/from a device
    388
    translator
    any program that converts source code into machine code. e.g. interpreters, compilers and assemblers
    389
    Disadvantages of Networks
    The user can become dependent on the network If the network stops operating then it may not be possible to access various resources Efficiency of a network can be very dependent on a network manager It is difficult to make a network of computer secure for hackers and outside threats As traffic increases on a network the performance can degrade
    390
    branch if zero instruction
    BRZ
    391
    RISC disadvantages
    complicated software more machine code (not as many instructions) lower clock speed, not good with complicated tasks
    392
    advantages of server side processing
    - doesn't require plugins or browser scripting technology - more secure - reduces loading time
    393
    third normal form
    1. Check the data is already in 2NF | 2. Check there are no non-key-dependencies
    394
    Disk defragmentation
    programs which attempt to consolidate the spilt files and free space. therefore reading and writing files becomes more efficient.
    395
    Trojan
    A Trojan is software that misleads the user of its true intent. Often, they serve to open up back doors in your computer.
    396
    Negation
    NOT
    397
    Layering
    the principle of dividing a complex system into separate slices of functionality
    398
    4 types of application software
    off the shelf, custom written, proprietary and open source
    399
    record
    an un-ordered data structure which is accessed through an attribute. It can store many different data types.
    400
    capacity of optical
    700MB - 50GB
    401
    branch if zero or positive instruction
    BRP
    402
    Memory Address register (MAR)
    stores the address of instructions and data that need to be fetched from or sent to memory
    403
    Advantages of using byte code interpreters
    - Achieve platform independence | - Acts as an extra security layer between program and computer
    404
    Bus topology advantages
    Inexpensive to set up Devices can easily be added Good for small networks
    405
    pipelining disadvantages
    only good if you can predict subsequent instructions. If the wrong instruction is fetched it has to be thrown away wasting time.
    406
    create a new table SQL
    CREATE TABLE tblName
    407
    Why is paging not efficient
    it does not take into account what the instructions in each page are doing
    408
    What is a mask?
    A mask allows you to isolate, extract, toggle and set bit values in a sequence of bits.
    409
    Clock speed Unit
    Hertz (usually gigahertz)
    410
    Port
    A port is used to alert a specific application to deal with data sent to a computer. These are used by protocols to specify what data is being sent.
    411
    Buses
    the communication channels between the CPU and the memory and other components.
    412
    Flash
    multimedia platform for creating and displaying graphics (replaced by HTML5)
    413
    Inserting items into a binary search tree:
    look at each node starting at the root. If the new value is less than the value at the node, move left otherwise move right. Repeat this for each node arrived at until there is no node. Insert a new node at this point and enter the data.
    414
    What does ASCII stand for
    American Standard Code for Information Interchange
    415
    Negatives of Symmetric encryption
    There is a security risk as the key may be intercepted or the process of creating the key may be duplicated meaning the data can be decrypted by a third party.
    416
      unordered list
      417
      Non pre-emptive algorithms
      - First come first serve | - shortest job first
      418
      Benefits of asymmetric
      - no movement of keys, more secure | - can be used for digital signatures
      419
      data storage instruction
      DAT
      420
      binary search tree
      dynamic data structure which can grow and shrink during a programs execution. It allows for efficient sorting, searching and retrieval of data. a binary tree can have 0, 1, or 2 children only.
      421
      Optical storage disadvantages
      slow access speed the surface of the disk degrades over time scratches can corrupt data
      422
      What does an OS provide?
      - User interface - Memory Management - Interrupt handling - Processor scheduling
      423
      writing to a file
      myFile = openWrite(“sample.txt”) myFile.writeLine(“Hello World”) myFile.close()
      424
      Why Do RISC processors result in increased battery life
      - smaller instruction set - fewer transistors/ less complex circuitry - less power required
      425
      Negatives of increasing clock speed
      more heat generated meaning computers must be cooled (either with heat sync/fan or water/oil cooling)
      426
      Timer Interrupts
      Triggered regularly by a timer, to indicate that it is the turn of the next process to have processor time- this allows for multi tasking
      427
      AND
      if both inputs are true the output is true else the output is false
      428
      Method
      a subroutine associated with an object
      429
      Wide Area Network (WAN:
      a method of connecting remote computers or networks. Typically made up of smaller LANs which have been connected together.
      430
      ROM
      non-volatile read only memory embedded into the motherboard of a computer and used to hold important instructions the computer needs for starting up
      431
      examples of system software
      Operating system, Utility Program, Library Program, Translators.
      432
      why can assembly code for one processor not work for another processor
      each type of processor has its own unique instruction set
      433
      Device drivers are...
      hardware dependent and OS specific
      434
      Database
      Databases are structured, persistent collections of data.
      435
      Uses of RISC
      used in most smart phones and tablets based around an ARM processor
      436
      boot up process of a computer
      - POST is run - clears anything in the registers - loads the address of the first instruction of the boot program into the PC - the boot program checks for start-up instructions on the BIOS - The OS kernel is loaded
      437
      What is bitwise manipulation useful for?
      - Compression Algorithms - networks (protocols. routing packets) - multiplication and division
      438
      Wireless Access Point
      use wireless to connect a node to a WiFi network avoiding the need for lots of physical caballing
      439
      X∧1=
      1
      440
      fixed point binary
      positive of the binary point is fixed on the number line
      441
      preorder traversal
      1. Visit the root 2. Traverse the left sub-tree 3. Traverse the right-sub-tree
      442
      Parallel processing/concurrent processing
      multiple processors working at the same time
      443
      Agile Modelling
      - Methodology which stages of software are not completed in a linear sequence - Throughout the process feedback is obtained which changes the software - It is a smaller version of spiral
      444
      Advantages of the spiral model
      - good from projects with high levels of risk | - suitable for large scale problems
      445
      benefits of symmetric
      - encrypted very quickly | - simple and easy
      446
      Co-processor
      a processor designed for specific purposes which can carry out specialised tasks more quickly than a regular microprocessor. execute concurrently with the main CPU
      447
      width CSS property
      width
      448
      advantage of normalisation
      it stores the most accurate version of that number.
      449
      Load instruction
      LDA
      450
      while loop pesudocode
      while condition= code endwhile
      451
      Virtual storage
      (cloud storage) when data is stored over the internet on cloud storage instead of on local storage device
      452
      Von neumann architechture
      - instructions and data share the same memory space - instructions and data served by the same system bus - instructions and data are stored in the same format - single CU and ALU
      453
      Disjunction
      OR
      454
      Procedural programming languages
      programming languages where the user gives step by step instructions of what to do
      455
      automated decision making
      computers make decisions and take actions based on sets of pre-defined rules and parameters without human involvement
      456
      compression
      programs which attempt to reduce the amount of physical space that files take up when they're stored
      457
      system bus
      collective term for address, data and control bus
      458
      RIPA year
      2000
      459
      Flat File
      single table database. It is inefficient as it is difficult to query and leads to data redundancy which can cause errors.
      460
      Shortest remaining time (SRT)
      The ready queue is sorted on the estimated time to complete the process. If the remaining time of a running process is longer than a new process the new process will be moved to the running state
      461
      Bitwise shifts can be used ...
      to change numbers quickly
      462
      digital signature
      hash total is encrypted using the users private key. If the receiver can decryptit using the senders public key they know that the message is authentic
      463
      Uses of Multi-user operating systems
      schools and offices
      464
      censorship
      the deliberate supression of material, either in the form of what can be published or what can be accessed
      465
      Benefits of high level code (over assembly)
      - optimisers may make code more efficient - intuitive and easier to write - can be recompiled for different architechtures - less code is written (shorter programs)
      466
      Internal css vs external css
      internal is within the document external is linked to html code
      467
      inorder traversal
      1. Traverse left sub-tree 2. Visit the root 3. Traverse the right sub-tree
      468
      Syntax analysis
      (stages of compilation stage 2) the syntax is checked against the rules and an abstract syntax tree is created if any code breaks the syntax rules an error is generated
      469
      Condition between two values SQL
      WHERE x BETWEEN a AND B
      470
      The Regulation of Investigatory Powers Act
      gives certain bodies the right to monitor communications and internal activity. It was made due to modern threats from criminals and terrorist organizations.
      471
      flip flop logic gates
      Two NAND gates with two inputs. The result of of each is the second input for the other.
      472
      Benefits of assembly code (over high level)
      - efficient as the code is more specifc - direct control of hardware - good if no compilers/interpreters installed - good if limited memory
      473
      DIV
      integer division (rounds down)
      474
      Round robin (RR)
      each process is allocated a specific amount of time known as a time slice or quantum. if a process is not complete at the end of the time slice it returns to the back of the queue, so the next process can have its turn.
      475
      Pre-emptive algorithms
      - Round Robin - Shortest Remaining Time - Multi-level feedback queue
      476
      Multi-level feedback queue
      uses multiple queues based of the priority of the process.
      477
      Uses of Hashing
      - generating disk address | - storing and checking passwords
      478
      postorder traversal
      1. Traverse the left sub-tree 2. Traverse the right sub-tree 3. Visit the root
      479
      full image tag
      480
      Requirements specification
      A document listing all the functionality the system should have
      481
      X∧¬X=
      0
      482
      external storage examples
      DVDs, CDs, Blue-ray, USB pens, SD card, Portable solid state drive, Mass storage tape, cloud storage.
      483
      Meta tags, keywords, descriptions
      Search engines look for this to find the content that matches your search
      484
      the tag to include JavaScript code
      485
      Absorbtion Law AND
      ``` A∨(A∧B) = A X OR (X AND Y) is the same as X ```
      486
      iteration
      do a set of statements again and again (looping)
      487
      delete rows of a table
      DELETE FROM WHERE
      488
      Bottleneck data bus
      A wider bus can transmit larger values/ more bits per instruction
      489
      Encapsulation
      the protection of attributes and methods of an object so that they can't be accessed or altered by other objects. (keyword - private)
      490
      Where is RAD used?
      good for when the project requirements aren't completely clear from the outset
      491
      Multi-user operating system
      more than one user is able to use the computer at one time. The operating system manages user preferences. Tis is often used for servers.
      492
      Subclass
      the new class which inherited from the superclass
      493
      condition controlled time
      repeat a set number of statements until a condition is met
      494
      mantissa
      the actual number you want to store
      495
      Application Programming Interface (API)
      a set of tools that can be used for building software applications.
      496
      Where is extreme programming used?
      good for when the requirements change
      497
      Algorithm for insertion into a stack
      1. Check to see if the stack is full 2. If the stack is full report error and stop 3. Increment the stack pointer 4. Insert new data item into location pointed to by the stack pointer and stop
      498
      Accumulator
      stores the result of calculations made by the ALU
      499
      scheduler
      A program that manages the amount of time different processes have in the CPU
      500
      Control Unit
      Control Unit is a register in the CPU that controls and co-ordinates the activity of the CPU. Control signals are sent along the control bus between the control unit and the other components of the computer.
      501
    • ``` The individual parts of the list
      ```
      502
      example uses of flip flops
      - in registers | - static RAM
      503
      distributed operating systems
      combing the processing power of multiple computers for a single task across a network. The OS controls and co-ordinates the computers, presenting it to the user as if it were a single system.
      504

      heading text
      505
      Spiral Model
      - designed to try and manage risk. made of four stages: 1. determine objectives 2. Identify and resolve risks 3. development and testing 4. plan next iteration
      506
      Antivirus utility software
      programs which help to detect and remove malicious programs which are often designed to harm the computer.
      507
      ROM acronym
      read only memory
      508
      segmentation
      when memory is split up however the logical divisions of a program are kept together, rather than having fixed page sizes
      509
      CSV (Comma Separated Value)
      A text file/format with values separated by | commas
      510
      Backing Up
      programs which allow for manual or automatic backing up of files onto another disk, on the existing computer system, to a removable device such as DVDs or CDs, to a network file server or to a cloud based storage system online
      511
      order of main HTML tags
      512
      RAM
      fast read-write volatile memory that stores the data and programs the computer is currently using e.g. OS, Programs currently in use, data that the programs are accessing
      513
      Memory write signal
      causes data on the data bus to be written into the addressed location in RAM
      514
      Purpose of Compression
      1. Reduce download times 2. Reduce requirements on file storage 3. Make best use of bandwidth
      515
      PDF
      portable document format, to display documents exactly as intened
      516
      d page rank
      The damping factor to prevent the rest of the equation from having too much influence
      517
      ¬(¬A) =
      A
      518
      relationship between the DNS server and IP addresses
      a registered domain name is held on the DNS server. The corresponding IP address to a searched domain name is loaded on the users computer.
      519
      Worm
      A Worm is a standalone program that does not require a user to run it in order for it to spread.
      520
      Disadvantages of the waterfall model
      - The absence of user feedback - not suitable for large projects - Requirements must be very well understood
      521
      positives of multiple cores
      may speed up processing
      522
      Arithmetic Logic Unit
      Carries out calculations and logic (Comparisons of binary)
      523
      Control signals
      - Memory read - memory write - bus request - clock signal
      524
      by default how are parameters passed?
      by value
      525
      Boolean
      Any true/ false data types which often represent logical situations
      526
      closed source software
      software which is supplied pre-compiled. The source code is not available and often copyrighted, also known as proprietary software e.g. microsoft word
      527
      GIF
      graphics interchange format, lossless compressed image file format
      528
      Transport Layer
      (2) Makes and breaks connections with routers
      529
      Registers
      Registers are small storage locations used to hold data temporarily. They have high read and write speeds.
      530
      Deleting an item in a hash table:
      1. Feed in key to hash function 2. Go directly to array index (HashValue) 3. If the value is equal to the value you’re searching for then mark as empty 4. Else follow the linked list in sequence until you find the value then mark as empty and update the free pointer in the linked list.
      531
      persistent
      the data remains for as long as its required
      532
      Transaction Processing
      Transaction processing is any information processing which is divided into individual, indivisible operations each operation must secede or fail as a complete unit.
      533
      Order Queried data SQL
      ORDER BY
      534
      Where is the spiral model used?
      Used in large scale projects
      535
      MAN
      metropolitan area network
      536
      need for secondary storage
      Can retain contents when the computer's power is turned off. This includes the Hard drive, optical media and solid state storage.
      537
      reading from a file
      myFile = openRead(“sample.txt”) x = myFile.readLine() myFile.close()
      538
      Camera/eye tracker
      Move/blink to send signal
      539
      Object
      Instance of a class
      540
      immutable
      structure and data cannot be changed at runtime
      541
      relational databases
      multiple tables linked together
      542
      data bus width
      same as the computers word size
      543
      indexing
      used to quickly access and locate data in a table
      544
      When is Bitwise ANDing useful?
      useful for TCP/IP and routing
      545
      nodes with no sub-nodes
      leaf-nodes or terminal nodes
      546
      Check if an attribute is similar to a given value SQL
      LIKE
      547
      Decode
      The contents of the CIR are sent to the CU and divided. The Opcode tells you the instruction to be carried out and the operand stores the address of any data which might be needed, the operand is sent to the MAR and the data is fetched from memory and stored in the MDR
      548
      Loaders (dynamic linking)
      compiled versions of libraries are stored by the computer and the operating system links the code directly into the program when it is needed reducing the size of programs. Loaders are needed to include or load the libraries into memory ready for use.
      549
      composite key
      A composite key is a combination of two or more columns in a table that can be used to uniquely identify a row.
      550
      Advantages to Peer-to-peer networking
      - Cheap - Enables users to share resources - not difficult to maintain
      551
      assignment operator
      single equals, sets the value on the right equal to the value on the left
      552
      Interrupt register
      generates and detects interrupts
      553
      constructor method
      signified by the key word new, initiated instantiation
      554
      lexical analysis
      (stages of compilation stage 1) white space is removed remaining code is turned into tokens a symbol table is created (including variables, data types and scope)
      555
      Isolation
      a transaction must not be able to be interrupted by anther transaction. The transaction must occur in isolation so that other users or processes cannot have access to the data concerned.
      556
      assembly language
      a low level language represented by mnenomics which represents the machine code.
      557
      more bits in the exponent...
      improves the range but reduces accuracy
      558
      constant
      name used to refer to a fixed value. The value is set when the code is written and cannot change while the program is running
      559
      RISC advantages
      very simple hardware/circuitry less silicon needed each instruction is a single machine cycle therefore pipelining can be used to improve performance lower energy consumption (can go into sleep mode)
      560
      collision (hash table)
      when the same hash value is given by two different keys
      561
      advantages of Client-Server
      - User IDs, passwords and access levels centrally controlled - Backup is centralised and usually automated - No access to other users’ files
      562
      breadth first traversing
      It starts at the root node, and visits all of the neighbor nodes at the present depth prior to moving on to the nodes at the next depth level.
      563
      negative of increasing cache size
      expensive
      564
      Multitasking operating system
      can run multiple programs simultaneously
      565
      defines a form that is used to collect user input
      566
      function
      a sub-routine that make take one or more parameters and ALWAYS returns a value
      567
      Full adder inputs/outputs
      inputs: the two bits to add, the previous carry bit outputs: the result, the carry
      568
      string
      any combination of letters, symbols, numbers, characters or control characters e.g. Hello, £4.56
      569
      magnetic storage examples
      magnetic tape, floppy disks hard disk drives
      570
      optical storage
      data is written to the surface of a reflective disk using pits (depressions) and lands. A laser beam passes over the surface of a land and the light beam reflected back is interpreted as binary values.
      571
      Uses of the internet
      communication, information, entertainment, education, financial transactions, controlling devices
      572
      tags
      mark out elements on a web page to indicate to a browser how to display or process an element
      573
      Gateway
      A Gateway is required where data is travelling from one network to another using different protocols
      574
      clustering
      when you store the data in the next available space of a hash table increasing the chance of collisions
      575
      Distrubuted Operating Systems
      allows multiple computers to work together on a single task
      576
      Positives of increasing clock speed
      you can carry out more instructions in a given time; improved performance
      577
      priority
      given to an interrupt to determine how fast they are executed
      578
      normalising: | moving the point to the right
      - exponent
      579
      HTTP
      Hypertext Transfer Protocol – used by web servers and browsers to transfer webpages.
      580
      operand
      the data the instruction applies to
      581
      Star Topology advantages
      Easy to isolate problems Good performance More secure is a switch is used a data is sent only to the recipient
      582
      Distribution LAW (OR)
      ``` A∧(B∨C)=(A∧B)∨(A∧C) A AND (B OR C) is the same as (A AND B) OR (A AND C) ```
      583
      depth first traversing
      follows one path down to a child node, it the visits this then backtracks to the next level then moves down to the next child node.
      584
      Solid-State storage advantages
      Durable No moving parts fast access time
      585
      application software
      any software which allows a user to carry out a task on a computer
      586
      Assembly code
      A set of simple instructions displayed as Mneumonics which is unique for each processor/hardware.
      587
      Internet Layer
      (3) provides links across different network types.
      588
      magnetic storage
      where metal disks called platters are magnetised. a read-write head moves very close to the platter and is able to detect and modify the magnetic properties of the platter.
      589
      computer program
      a series of instructions that are executed one after another. follow the pattern: INPUT -> PROCESS -> OUTPUT
      590
      Bus Topology
      an arrangement where nodes are connected to a central communication channel. Each end of the backbone is connected to a terminator. Each node is passive and data is sent in one direction at a time only
      591
      Software interrupts
      - Arithmetic overflow | - Illegal instruction encountered
      592
      Advantages of extreme programming
      - Acknowledge user input - Useful for when there is a danger of getting sidetracked by suggested improvements - cost and time saving - constant feedback - Has a very high emphasis on programming so quality of end code likely to be very high.
      593
      Where is agile methodologies used?
      large projects where there is a lot of collaboration
      594
      random files
      which allow you to access any item without having to search through the file from the start
      595
      Foreign key
      a foreign key is a field in one table that uniquely identifies a row of another table
      596
      Circuit Switching
      Circuit Switching: a complete circuit or route between two nodes is established before transmission begins. Once the rout is established all data follows this route until transmission is complete.
      597
      assembler
      converts low level assembly language directly into machine code. this is a one to one relationship and is processor specific
      598
      Why is it necessary to have a variety of programming languages?
      - different languages suit different jobs | - developers prefer certain languages
      599
      Record/Tuple
      the rows (a data set that applies to one item)
      600
      inorder dot
      below
      601
      FTP
      File Transfer Protocol – Used by clients and servers to upload and download files across the internet
      602
      switch/case pseudocode
      ``` switch condition: case “A”: code case “B”: code default: code endswitch ```
      603
      interrupt service routine
      when the processor receives an interrupt and must stop what its doing in order to service the interrupt and run that code.
      604
      polling
      the CPU checks with each device if it needs its attention. | This is inefficient and wastes time as some devices will not want attention when called upon.
      605
      Router
      devices which are used to connect networks. they receive data packets from one network and based on the address on the packet forward them of
      606
      styling of elements CSS
      h1{ color:blue; }
      607
      MAC Address
      identifier that is permanently added to a device by the manufacturer
      608
      dense graph
      A graph which has more edges in relation to vertices
      609
      delete full tables SQL
      DROP TABLE table_name;
      610
      device driver
      software that tells the operating system how it can communicate with a device
      611
      Searching for an item in a linked list:
      1. Set the pointer to the start value 2. Repeat: a. Go to node (pointer value) b. If the data at the node is the search item i. Output the data and stop c. Else i. Set the pointer to the value of the next item pointer at the node d. Until pointer = 0 3. Output data not found
      612
      Run Length Encoding
      Run length encoding is used when there is repeated redundant data. It stores the item once and then an index with how often the item is repeated.
      613
      Phishing
      Phishing is using email to manipulate a victim into visiting a fake website and giving away personal information.
      614
      Control Bus
      A bi-directional bus to transmit command, timing and specific status information between system components
      615
      Rapid application Development
      - user is shown a prototype and gives feedback to inform how the prototype is further developed until the final project is complete
      616
      Emulators
      provide an illusion to a user/program that it is running on its native hardware when in fact it is on an entirely different machine
      617
      purpose of operating systems: providing a user interface
      allowing users to interact with applications. This may be graphical (GUI and WIMP), menu driven or command line
      618
      The Waterfall Lifecycle Model
      - a sequence of stages. each stage can only start after the previous one is complete. - it possible to go back stages however you can't skip ahead - user involved once at the beginning
      619
      Uses of symmetric encryption
      Used when the same person is accessing and saving data e.g. for backing up
      620
      breadth first traversing uses a
      queue
      621
      Disadvantages of a client-server network
      - expensive to install and manage | - professional IT staff are needed to maintain
      622
      Pagerank equation
      PR(A) = (1-d) + d (PR(T1))/C(T1) + ... + PR(Tn)/C(Tn))
      623
      Client-Server Model:
      one device (the client) requests services from another device (the server).
      624
      Flip Flop use
      used as a memory cell to store the state of a bit
      625
      count controlled loops
      repeat a set number of statements a fixed number of times
      626
      how does circular shifting work?
      you shift either way and the left over bit circles back around to the beginning.
      627
      BIOS acronym
      Basic Input Output System
      628
      border colour CSS property
      border-color
      629
      AND (*)
      630
      Special pupose application software
      A software that preforms single specific tasks. e.g. payroll, hotel booking systems or browser software
      631
      Distribution LAW (AND)
      ``` A∨(B∧C)= (A∨B)∧(A∨C) A OR (B AND C) is the same as (A OR B) AND (A OR C) ```
      632
      magnetic storage negatives
      slow access speed | moving parts make it vunerable
      633
      index sequential files
      for very large data sets the order of the index is maintained so the data can be accessed in an order
      634
      What are the two most common character sets?
      ASCII and Unicode
      635
      Why are protocols Important
      allows computers to communicate by ensuring all devices follow rules so they interpret signals in the same way
      636
      Data Protection act
      sets out requirements for the control or storage of individuals personal data. In a company the data controller has to control the processing and storage of data based on the data subject.
      637
      virtual memory disadvantages
      it is not efficient. time is spent relocating part so program to the hard disk meaning there is less execution taking place, this is known as disk thrashing. the CPU can't execute instructions from the Hard disk so instructions must be bought back which is slow and wastes time
      638
      Full adder
      combines two half adders, used to add a series of bits
      639
      Real-time operating systems
      used in safety critical environments such as air crafts or hospital equipment. processes are guaranteed to be executed in a known time frame, there is plenty of redundancy built in so that the system can handle unusual interrupts. The processors never run at capacity.
      640
      A∨ ¬A =
      1
      641
      optical storage examples
      CDs, DVDs, Blue-ray disks
      642
      subtract instruction
      SUB
      643
      similarities between paging and segmentation
      both allow programs to run despite insufficient memory both pages and segments are stored in a disk both pages and segments are transferred into memory when needed
      644
      queue data structure
      A queue is known as a FIFO structure. A pair of pointers is used to point to the front and back of the queue. If an item is popped from the queue the front pointer points to the item being popped. If an item is pushed onto a queue the tail pointer increments by one and points to the new end of queue.
      645
      Formats of data
      - CSV (Comma Separated Value) - XML (eXstensible Markup Language) - SQL (Structured Query Language)
      646
      DPA year
      1998
      647
      Network
      an interconnected set of devices
      648
      Bitwise ORing ...
      sets a subset of the bits in the value you use 1s where you want to set values and 0s when you want to leave them alone
      649
      Aims of scheduling
      - to provide an acceptable response time to all users - To maximise the time the CPU is usefully engaged - To ensure fairness on a multi-user system
      650
      IP
      Internet Protocol – used to transfer all packets across the internet between routers
      651
      output instruction
      OUT
      652
      Protocol
      A protocol is a set of rules relating to the communication between devices.
      653
      Advantages of self driving cars
      - safer than a human driver (due to quicker reaction speeds etc.). - cheaper as no wage to cover. - less likely to make mistakes with route
      654
      Paging
      Memory is split up into physical sections which are all the same fixed size
      655
      background colour CSS property
      background-color
      656
      hardware interrupts
      power/reset button is pressed | memory parity error (corrupt memory)
      657
      Masks can be used ...
      to set and toggle specific bits in a larger sequence.
      658
      Disadvantages of Peer-to-peer networking
      - used for torrent downloading | - When they all want to be used at once it becomes difficult to share resources
      659
      immediate addressing
      when the value in the operand is the actual value to be used. this means the memory does not need to be searched
      660
      stages of compilation
      Lexical analysis syntax analysis code generation code optimisation
      661
      Traversing data from linked lists:
      1. Set the pointer to the start value 2. Repeat: a. Go to the node b. Output the data at the node c. Set the pointer to the value of the next item pointer at the pointer d. until pointer = 0
      662
      Library Programs (System Software)
      contains useful functions that are frequently used by programs. Simplifies the process of application development.
      663
      TCP
      Transmission Control Protocol – used with IP to ensure error free transmission and package switching
      664
      Exclusive Disjunction
      XOR
      665
      Libraries
      pre-compiled pre-tested sets of code, often with hundreds of ready to use routines available to the programmer.
      666
      procedure OO pseudocode
      public procedure code endprocedure
      667
      X∨1 =
      X
      668
      Feasibility study
      the initial investigation that determines whether a project is viable before time and resources are invested into it
      669
      Web Forms
      Enable websites to collect user input. Javascript is used to add behaviours to the script
      670
      Insert data into a table SQL
      INSERT INTO tblName
      671
      Data redundancy
      the unnecessary duplication of data in a database. When updates occur, all the instances of a data item must be changed. This leads to errors and also wastes storage space.
      672
      Positives of increasing cache size
      less time fetching data; improved performance
      673
      role of JavaScript
      the code interactivity into webpages
      674
      Disadvantages of self driving cars
      - May not be able to understand natural speech. - May be limited in terms of the roads on which it can operate. - Vulnerable to hacking. - Only as good as the program running it – a bug in the code could cause catastrophic accidents. - May prioritise safety of pedestrians over that of the passenger. (e.g. may take actions that may put the passenger at risk to save the lives of numerous people outside the car.) - No discussion possible with the driver / no "human presence" to reassure nervous customers.
      675
      fetch decode execute cycle
      ``` PC MAR Address Bus Memory Data bus MDR CIR Decode Unit ```
      676
      font CSS property
      font-family
      677
      Variable length fields
      an element may use a different number of bytes to another element for example a different number of characters. Means it only uses the necessary amount of storage
      678
      two types of software
      system and application
      679
      CSS class
      DOT .infoBox{ background-color: green; }
      680
      virtual machine
      Where software is used to take on the function of the machine, including executing code or running an OS within another to emulate e.g. when you install windows on OSX
      681
      Fetch
      1. The address of the next instruction is copied from the PC to the MAR 2. The fetch signal is sent across the control bus. The content of the MAR are transferred across the address bus. 3. The contents of the memory location stored in the MAR are sent across the data bus and stored in the CIR 4. the PC increments by 1
      682
      Client-Server Networking
      One or more computers know as clients are connected to a more powerful central computer known as the server
      683
      compiler
      converts high level code to object code. | this is a one to many relationship and means programs can be distributed without the source code
      684
      storage device
      any computer hardware used for temporary or permanent storage of data. They can be internal or external to a computer.
      685
      indirect addressing
      where the operand contains the address which contains the address where the value can be found. useful because it means that the larger addresses in memory can be used to store data.
      686
      nodes lower than the root node
      children
      687
      update attribute SQL
      SET
      688
      turing complete
      a programming language is able to solve all the problems a computer is able to solve.
      689
      flip flop clock diagrams
      on each rising edge of the clock change the result to whatever the input is (it may not need changing)
      690
      Serial files
      * Permanent storage of data * Data is stored in the order in which it was entered * No order to the data is maintained * Useful for storing transactional data and initialisation files
      691
      positives of computers in the workplace
      more effective communications removal of humans in construction processes shifting skill sets
      692
      insert items into a table
      INSERT INTO table_name (column....) | VALUES (value...)
      693
      layered operating system
      each layer only interacts with the layer next to it user -> application -> operating system -> hardware
      694
      add instruction
      ADD
      695
      get the substring
      stringname.subString(startingPosition, numberOfCharacters)
      696
      Database Management System
      software that handles the data that is stored in secondary storage.
      697
      SQL similar elements
      LIKE
      698
      What determines the format of a machine code instruction
      - the word size | - the width of the address bus
      699
      branch always instruction
      BRA
      700
      Timestamp ordering
      every object has a read timestamp and a write timestamp meaning if the read timestamps are not the same the DBMS knows another user has accessed the same object
      701
      Processor Scheduling
      The OS can queue up processes for the CPU to make the most efficient use of the computer which gives the illusion of multitasking
      702
      SQL (Structured Query Language)
      A language for creating/querying databases
      703
      3 programming constructs
      sequence, selection, iteration
      704
      RAM acronym
      Random Access Memory
      705
      limitations of arrays
      they can only store one data type | they're a static data structure
      706
      Benefits closed source software
      - companies have a lot of resources providing security if the program doesn't work, service/support, and a more polished user friendly product
      707
      depth first traversing uses a
      stack
      708
      Sequential Files
      * Store data in order of a key field | * The order is maintained when new records are added
      709
      four ways of addressing memory in a computer
      immediate direct indirect indexed
      710
      inheritance
      enables new objects to take on the properties of existing objects
      711
      character
      Any single letter, symbol, number, character or control character
      712
      SAN
      storage area network
      713
      Domain Name System Server (DNS sever)
      System thats stores names for IP addressees on a network
      714
      Uses of client-server networking
      File Server holds and manages data for all clients Print Server manages print requests Web server manages requests to access the web Mail server manages the email system Database server manages database applications
      715
      Clock speed
      Indicates the number of instructions the CPU can process per second.
      716
      MPEG
      motion picture experts group, a compression standard for audio visual and data files
      717
      SQL query
      SELECT FROM WHERE
      718
      file managers
      programs which allow users to easily copy, delete, rename and modify files on a computer system
      719
      non key dependency
      where the value of an attribute is determined by the value of another attribute which is not part of the key.
      720
      Attribute/field
      the columns (describes the characteristics of each record)