Term 2 Flashcards
(239 cards)
1
Q
Input devices
A
- mouse
- stylus
- touchscreen
- mic
- webcam
2
Q
the CPU is responsible for..
A
- Executing instructions
- performing calculations
- making logical decisions
3
Q
Output devices
A
Designed to allow users to access/take data from a computer system.
- Monitor
- Speakers
- Printer
4
Q
I/O devices (in/output)
A
Known as the peripheral devices
5
Q
Main Memory
A
May be volatile (RAM) or not (ROM), also includes cache memory and virtual memory.
6
Q
Secondary storage
A
allows for long-term storage data and instructions
- Internal: HDD, SSD
- External: External HDD, Memory stick, memory card, optical disks
7
Q
Stored Program Concept
A
Data and instructions are stored in the same memory at the same time.
The CPU follows a sequential fetch-execute cycle.
A computer system with one CPU
8
Q
RAM (Random access memory) temporarily..
A
Stores data and instructions for the computer’s CPU to access quickly.
- Can read/write
- Volatile (Lose its content when no power, must be constantly refreshed)
- DRAM
- SRAM
9
Q
Dynamic RAM (DRAM) is compromised..
A
on integrated circuits.
- Millions of transitions and capacitators
10
Q
DRAM acts..
A
like a switch
11
Q
DRAM holds…
A
one bit
12
Q
DRAM is like..
A
a small battery
13
Q
DRAM needs to recharge..
A
every ~15 sec
14
Q
DRAM allows…
A
the chip to control the circuit to read the capacitator.
15
Q
DRAM needs to be constantly…
A
refreshed to recharge the capacitators otherwise data will be lost.
16
Q
Static RAM (SRAM)
A
- Uses flipflop logic circuits
- retains the state of a single bit unless stated otherwise
- no need for refresh
17
Q
DRAM > SRAM
A
- costs less
- less power needed to run
- higher storage capacity
18
Q
SRAM > DRAM
A
- Faster data
>DRAM = ~60nanosec
>SRAM = ~25nanosec
19
Q
ROM (Read only memory) stores
A
- Bootstrap loader
- System settings (BIOS, UEFI)
- Character map (ASCII/Unicode)
20
Q
ROM can only be..
A
read from
21
Q
ROM is..
A
non-volatile
22
Q
ROM has a separate..
A
power source (CMOS battery)
23
Q
ROMs’ contents must..
A
be available when computer turns on
24
Q
Cache Memory is..
A
- a super fast memory built into a processor
- Located inside the processor
- even the slowest beats RAM.
25
Cache contains..
frequently accessible data/instructions
26
Cache uses..
SRAM
27
Cache cost..
is expensive to make
28
Cache capacity
small
29
Cache allows the processor to..
access data and instructions more efficiently than having to access these from RAM each time.
30
Level 1 Cache
- Primary
- Located in processor chip
- Works at speeds only a little slower than processor
- Small capacity (8-128 kB)
31
Level 2 Cache
- Located on processor chip
- Slower
- Larger storage (512kB-8mB)
32
Level 3 Cache
- Often on motherboard
- Slower than other 2
- Moderate storage capacity (8mB)
- Stores data that is shared between the processor core.
33
Level 4 Cache
- Not all motherboards support
- Newest cache
- Slowest
- Greatest storage capacity
- Typically used to share data between CPU and GPU
34
Virtual Memory is..
a way computers deal with limited space in RAM
35
Virtual Memory has a section of the..
HDD/SSD that is reserved for storing data from RAM
36
Virtual Memory memory type
temporary memory (volatile)
37
Virtual Memory uses the operating systems to..
move data and instructions when RAM is nearly full
38
Virtual Memory needs to..
be transferred back to RAM before the processor may access it if the user requires to access something from Virtual Memory
39
There are blocks...
of data that are transferred between RAM and Virtual Memory
40
Blocks are called...
Pages
41
Process of pages is called..
page swapping
42
Disadvantage of page swapping
Too much use of Virtual Memory slows down the computers performance
43
Storage devices
locating and interacting with data
44
some programs can be modified when running but...
this is bad and caused by a virus
45
Optical Storage
- DVD
- CD
- Blu-ray
46
Electronic Storage
- RAM
- Flash Drives
- SSD - Solid State Drives
47
Magnetic Storage (HDD) is..
A magnetic disk spins, the magnetism causes electricity to flow in the 'read/write' head suspended very closely to the surface of the hard disk.
This flow is interpreted in 1 and 0.
48
CHS addressing
- to "read" a file or part of a file you need a cylinder, head, sector number
49
Optical disks have...
different pattern dots using "burners" representing the types of info stored on disk
50
Track pitch
distance between the adjacent parts of tracks
51
Pit size
size of the physical bit (or pit)
52
Locating data in optical disks - DVD-R(w)
extra data is written between the 'grooves'
53
Locating data in optical disks - DVD+R(w)
- extra data written in the track itself
- most people think this is better
54
SSD - solid state disk
- Permanent electronic memory
- 'charge trapped memory' which is stored a 1
- data read in blocks, sequential access
55
SSD uses EEPROM which stands for..
Electronically Erasable Programmable read-only memory
56
EEPROM memory cells use..
multiple layers of semi-conductors to trap electrons, these represent a 1.
57
Advantages of Cloud Storage
- easy access
- not device dependent
- sharing
- multi-user accessibility
- no depending hardware
- sync is auto
58
Disadvantages of Cloud Storage
- ownership is compromised
- dependent on internet connection
59
Secondary storage
Provides long-term storage for:
- data
- instructions
60
What is an HDD?
- circular platters coated in iron particles
- read/write heads move in between platters
- Experiences latency because of the HDDs moving parts required to read/write
61
Latency
the time taken for a specific block of data to a track to rotate around to the read/write head
62
All screens must have:
- Pixels
- A light source
- A way of coloring panels
- A way to control the brightness of the pixels
- Ability to turn the pixels on and off quickly
63
LCD Screens
- Liquid Crystal Displays
- Structure can change with electricity and will rotate polarized light which will allow some light through.
64
LCD Light source
white light from the sides or a series of small LEDs behind the screen
65
LCD Color
Colored filters
66
LCD intensity
combination of polarizing filter and LCD (sending electricity to an LCD controls how much light is blocked/passed by the polarizing filter)
67
LED light source
individual LEDs
68
LED color
each LED is colored
69
LED intensity
The amount of electricity sent to each LED controls how much light is produced
70
2 types of LED
Organic and crystal
71
Screen layers I
V
LED strip
Bottom glass substrate (FPC & IC on glass)
Liquid crystal
Common electrode
Color filter (RGB)
Top glass substrate
72
Plasma Screen Light source
heating up gas inside pixels - filled with gas. The heat turns the gas into plasma. The energy in the plasma hits the walls and turns into light
73
Plasma Color
coloring each pixel wall a certain color
74
Plasma Intensity
the amount of electricity sent to each pixel, controls the amount of light produced
75
Resistive Touch Advantages
- affordable and widely accepted
- functional even with non-conductive inputs
- unaffected by water on the surface
76
Resistive Touch Disadvantages
- limited to single touch functionality
- less durable compared to other tech due to wear
- typically capped at smaller sizes
77
Infrared Touch Advantages
- high durability and resistance to wear and tear - supports multi-touch functionality
- works with any input such as fingers, gloves ect
78
Infrared Touch Disadvantages
- poor performance in direct sunlight or high-temp environments as infrared beams can be disturbed by external light sources
79
Optical Imaging Touch Advantages
- versatile input options
- durability and supports multi-touch
- ideal for large-scale applications
80
Optical Imaging Touch Disadvantages
- bulkier design compared to other touch panel types
81
Projected Capacitive Touch Advantages
- high-speed response and precision
- supports multi-touch
- durable surface resistant to scratches and wear
82
Projected Capacitive Touch Disadvantages
- Expensive
- Limited scalability for larger screens due to increased complexity and cost
83
CPU, a computer system that uses:
- a single processor (controlled unit)
- Main memory (RAM, ROM cache)
- Secondary memory (HDD, SSD)
- I/O devices
84
Main CPU components
- Control Units
- Arithmetic logic Unit
- Registers (Special/General purpose)
- Busses
85
Control Unit
managers and coordinates the operations of the CPU by interpreting instructions and directing other components
86
Arithmetic Unit (ALU)
- Performs mathematical calculations and logical operations.
- Does math and Boolean/relational comparison (true or false)
- Stores the accumulator (ACC)
87
Program Counter (PC) stores
the memory address of the next instruction to be fetched
88
Memory Address Register (MAR) stores..
the memory address of the current instruction to be fetched. Receives its content from PC
89
Memory Data Register (MDR) holds..
data being read from or written to memory. Acts like a buffer between CPU and RAM.
90
Current Instruction Register (CIR) stores
a copy of the MDR's contents. Responsible for decoding
91
Accumulator (ACC) is..
A register that stores intermediate and logic results during CPU instructions.
92
Register transfer notation (Fetch stage)
MAR <- PC
MDR <- MAR
IR <- MDR
PC <- PC +1
93
Opcode
an instruction in low level assembly language
94
Operand
a value or address
95
Instruction set
The low level commands that a particular family of processor understands
96
Buses
connections/pathways between;
- Different paths/registers within the processor
- between different components attached to a motherboard
97
Address bus
- Transmits memory (RAM) locations between the processor registers (PC and CIR) and MAR
- Unidirectional, Data flows one way
98
Data Bus
- Transmits data and instructions between the processor registers (MDR, CIR) and ALU
- RAM and the processor - visa versa
- HDD/SSD and RAM - visa versa
- Bidirectional, flows both ways
99
Control Bus
Sync communications between:
- registers and parts of the processor
- the processor and connected hardware
- Unidirectional
100
Control bus uses..
electrical signals to direct the computers system and execute instructions in stored programs
101
Factors of CPU performance
Clock speed
Cache memory - size and type
Number of cores
102
Clock Speed
- Measured in Gigahertz
- Specifies how many fetch- execute cycles may be completed each sec
- higher clock speed, higher job throughout
103
CPU Cores
- Multiple "processors" on a single CPU unit.
- Each processor usually has its own L1 and L2 cache.
- L3 cache is commonly shared by the cores
104
Status Register stores...
metadata about the CPU after the ALU operations
105
Index Register holds...
off set for memory addressing modes improving flexibility in accessing data.
- Used internally when
accessing data.
106
Communication needs..
- A Channel (A way to send Data)
- An address (A direction for where to send data)
- Data (content - though address info is also data)
107
Simple Serial (one wire 2 components)
- Communication between 2 components is simple as receiver always KNOWS where the data has come from.
- Transmitters always know where to send it (no need for address).
108
Serial benefits
- Data is sent one bit at a time down 1 wire.
- May have several bits travelling along the wire at a time (least significant figure first).
- Simpler and more reliable transmissions.
109
Parallel benefits
- Multiple data bits are transferred over multiple channels at a time.
110
Synchronous Communications
- The transmitters and receivers agree on how fast the data comes down.
- A clock is used to read the data at the right time.
111
Network Communications: The Mesh
Connecting many devices to each other gives a complex "mesh"
(Cant put a pic so imagine 6 dots in a circle with lines connecting all of them on the outside and a star on the inside)
112
Network Communications: The Bus
connecting many devices to the same wire (bus) is simpler than a mesh.
o o o
I I I
-----------------------
I I I
o o o
113
Serial Bus communication
- Data is put onto the buses and received by all devices
- Need to add "address" info to each set of data so right devices use it
114
Parallel Bus communications
- Uses many wires to send data.
- The devices can read the data on all the wires at once.
- Needs address info if sending between many devices.
115
Problem with Serial:
- Only one device can send data at once (without error)
Solution:
- If error detected, wait and resend.
- Send error checking data with content data.
116
Problem with Serial:
- Needs an addressing mechanism
Solution:
- Send address with data.
- Have another bus that controls addressing (used together with data bus to provide address info)
117
CPU - RAM communication uses..
parallel bus technology
118
CPU - RAM communication has data communication..
Only between the CPU and RAM on the data bus.
119
CPU - RAM communication address bus
the byte of RAM involved in the data transfer is written on the address bus.
- Only the CPU writes to
the address bus.
120
To fetch data...
- CPU "writes" a RAM address
- The byte in RAM located on address is put on data bus
- CPU reads data from data bus and sends it to one of the registers
121
Validation checks: Presence
make sure something is entered
122
Validation checks: Length
make sure something is the correct length
123
Validation checks: Format
make sure all rules are enforced. eg. needs a 1
124
Validation checks: Range Check
make sure all values are between certain max and minimum values. eg. cant have 30th of Feb
125
Parity
- Detecting small errors in transmissions of bytes.
- A simple method for error detection in digital communications
126
Parity uses..
extra bits to verify data integrity.
127
Serial uses
- Many cables today are serial.
- Bit rates vary, therefore today we can say that this is faster than parallel.
128
Parallel Uses
- Data and address sent between registers in CPU
- Older (80's) printer cables
129
Simplex
data transmitted one way only. eg. satellite TV broadcast
130
Half-Duplex
data transmitted both ways but one at a time. eg. walkie talkie
131
(Full) Duplex
data transmitted in both directions at the same time. eg. phone calls
132
Data packets
- Data is split into smaller chunks called packets before trans-missioning.
- Packets are the smallest unit that may be sent over a network.
133
Packet Header
- Source of IP address
- Destination IP address
- Protocol being used to transmit data.
- Packet number (and how many out of a packet)
134
Packet Payload
- The data itself
- Packet size varies (depends on network) -> approx 48 bytes - 4kB
- The source and destination IP address receives the payload
135
Packet Trailer
Contents differ depending on the networks but typically contains:
- Bits indicating the end of the packet has been reached.
- A Cyclic Redundancy Check (CRC) which tells the computer that all packets have been received
136
Packet Switching is known as..
the independent routing where packets are sent in order and arrive out of order (hence packet number for reassembly).
137
Packets may..
"re-route" a packet to another router if necessary.
138
Parity Bit Disadvantages
- Parity still might go through
- When error is identified, it cannot be fixed
139
Parity Byte Advantage
Can identify which bit has been received in error
140
Data Verification
Checks to ensure that data input is accurate when copied from hard-copy documents or when transferred between computers.
141
Data Verification: Double Entry
- Data entered twice
- Sometimes by different people
- Both entries are compared
142
Data Verification: Visual Check
A person manually compares what they have typed with:
- What they think they typed/did they type something into the text book they wanted.
- Hard copy documents whose data is being input to a computer system.
143
Data Verification: Checksum
- Data to be sent through a hashtag algorithm.
- Sent with the block of data.
- 2 checksums are compared. If the same, integrity of that data is maintained, if not the same, data has been compromised
144
Secure Sockets Layer (SSL) uses asymmetric...
encryption to create a secure link between computers
145
Secure Sockets Layer (SSL) uses digital...
certificates and signatures
146
Secure Sockets Layer (SSL) protocol in a web browser
Https or a locked padlock
147
Secure Sockets Layer (SSL) steps
1) Web Browser sends message to connect via SSL
2) Web Browser requests a digital certificate
3) Web server sends a copy of SSL certificate
4) Web Browser conforms that certificate and sends a message to start communication
5) Web server acknowledges and the SSL data-encrypted communication begins.
148
Transport Layer Security (TSL)
- A more secure version of SSL
- Ensures the security and privacy of data transmitted between devices.
- Data is always encrypted
149
Two layers of TSL: Record Protocol
Contains the data being transferred over the internet
150
Two layers of TSL: Handshake Protocol
Web server and web browser authenticate each other using encryption algorithms.
151
Substitution: Caesar Cipher
- The smallest and easiest to crack.
- Key tells us how many spaces to move in the alphabet.
- Eg: A ---> E moving 5 places
152
Transposition: Rail Fence Cipher
- Order of the letters are changed, not the letters themselves.
- Need to know the number of "rails" (or "rows")
153
Polyalphabetic: Vigenère Cipher
- Once thought to be unbreakable
- Uses a word-based bey and a key system (the word repeated)
- 'Vigenère square' uses the keystream to sub characters
154
What is a computer network?
a network is two or more devices that are connected to exchange data
155
Networks allow..
- sharing files
- messaging
- share resources
156
Advantages of networks
- Easily shares files and data
- share resources
- communication
- store data centrally
157
Disadvantages of networks
- Greater risk of hackers and viruses
- cost
- when network is down, computers cant be used as a standalone
158
How router works
1) connects network to the internet
2) connects LAN + network together
3) transfers data between networks
159
Router purpose
- Router can connect to devices wirelessly
- Stores info about which computer is connected to which network
160
Web pages are stored on
web servers
161
Web pages have unique..
IP address and domain names to find/communicate with each other
162
A switch sends specific packets of data to...
specific computers on the LAN workstations using MAC addresses
- expensive but secure
- connects to switch ports
- Learns all addresses
163
A hub sends data packets to...
all the workstations on the networks which cause network traffic
- poor security
164
How a switch works
- switch sends data to all to identify the correct address, communication is remembered and able to go back and forth
165
Modems convert analogue signals from a..
telephone line to a digital signal which can be read by a computer.
- visa versa for telephone lines
166
Network Interface Card (NIC) allows you to connect a device to the...
network and will contain the MAC address which is used to identify the computer to the network.
167
A bridge is used to connect two parts of a...
LAN network so they function as a single LAN.
168
Wifi is a wireless networking tech that makes it possible to..
connect devices with a wireless connection to a network or to a single computer
169
Wifi advantages
- reduced cost
- easier to connect
- makes device portable
170
Wifi disadvantages
- limited work area
- weaker signal
- slow data transfer
- less secure
- Physical obstacles
171
Bluetooth is a wireless networking tech designed for..
short range connections
172
Bluetooth advantages
- connecting wireless devices
- transferring files
- printing wirelessly
173
Bluetooth disadvantages
- very slow data transfer
- short distance signal
- less secure
- limited amount of devices
174
Satellite can be used almost anywhere in the world since...
it connects with better coverage because of satellites, generally used for the internet.
175
4G/5G are used in phones to connect to wireless internet and allows..
for access on the move even within areas with no wifi as well as not affected by rain or snow.
176
Internet Server Provider (ISP) sets up an account with ISP to..
connect to the internet in your location
177
LAN (local area network) covers a ..
small area and consists of a number of devices that usually connects to a switch
178
WAN (wide area network) expands over..
large geographical areas and created by joining several LANs together
179
WLAN (wireless LAN) has devices known as access points that are connected to..
the wired networks at fixed locations that provide the wireless access to devices on the network.
180
Internet
- Public
- Global
- Network of Networks
181
Intranet
- within one organization
- more policed/managed
- extra security
- data more reliable/relevant
182
Network Communications: The Star
computers can communicate with any other computer, but not at the same time
183
IP Address
The address the computers use, it is designed to be fast - but it is hard for people to read
184
URL
Universal Resource Locator
The address people use.
185
URL; Protocol
Describes the rules used to exchange data
186
URL; Domain
The computer/network name’s on the internet
187
URL; Path
(directory / sub-directory). Folder location of the resource on the computer
188
URL; File Name
name of the resource user requests, often an HTML filename
189
What is extra info on a URL?
- QueryString.
- Extra information sent along with the URL to the web server.
190
IP; v4
4 sets of numbers between 0-255
Written in dotted decimal format
E.g. 104.26.15.135
191
IP; v6
8 Sets of Numbers. Written as hex digits between 0 - FFFF, separated by “:”.
E.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334
192
IPv4 vs IPv6
- Pv4 uses a 32 bit number
- The largest value of using 32 bits is 2^32
- So many devices are connected to the internet, IPv4 addresses are exhausted
- IPv6 was invented to cope with the growth of the internet
193
Packet Switching
- The data is broken up into small packets, containing just a part of the whole message
- Lots of computers can share the same channel
----> users are sharing the connection
194
DNS (Domain Name System) purpose
Translating the URL Into An IP Address
195
The DNS system acts as a..
massive phone book for the internet.
196
For DNS URLs can remain the same but..
an IP address may change. Computers need to be able to get the correct IP address whenever they use the URL
197
The DNS system (URL-IP)
- The computer CAN NOT use a URL.
- URL need to be converted into an IP address
198
the hardware is for knowing..
what devices are needed to access the internet
199
A single device that connects to a network to the internet.
Gateway
200
Encoding technique where the public and private keys are different
Asymmetric
201
Proving user identity online.
Authentication
202
An attempt to crack a secret code by trying every possibility.
Brute Force
203
Number added to end of a sequence of numbers to prevent data entry errors
Check Digit
204
A random number generated from given data, used to detect errors in its transmission.
Check Sum
205
A secret code
Cipher
206
Encrypted text
Ciphertext
207
Any unwanted change in data
Corruption
208
Turning ciphertext back into plaintext form.
Decrypt
209
Taking ordinary text (known as plaintext) or other data and turning it into a form that others can’t understand.
Encrypt
210
The validity of data (knowing data has not changed)
Integrity
211
Data (number) used to encode or decode a message with a known algorithm.
Key
212
A way of cracking a cipher, by knowing the plain text of an encrypted message.
Known Text
213
An attempt to read a message by intercepting it while it is being transmitted.
Man-In-The-Middle
214
A simple verification technique involving the counts of 1's in a small block of transmitted data.
Parity
215
Ordinary, readable text.
Plaintext
216
Key that is not shared, within an encryption
system.
Private Key
217
Key that is shared within an encryption system
Public Key
218
Extra information used for checking
Redundancy
219
Encoding technique where the public and private keys are the same
Symmetric
220
A security technique where users need to provide 2 means of authentication
Two-Factor Authentication
221
Ensuring data is entered correctly
Validation
222
Ensuring data is transmitted correctly
Verification
223
An identifier of a computer primarily used in locating a computer on a network.
Address
224
A set of step-by-step instructions designed to complete a task.
Algorithm
225
A step (from node to node) in a packet's path through the internet.
Hop
226
Simple connection device (between 2 bus networks)
Hub
227
Utility used to display a computer's internet
details
IPConfig
228
Communication system where multiple bits are sent simultaneously (through multiple wires)
Parallel
229
Utility to test internet connectivity
Ping
230
A set of rules used in computer-computer communication
Protocol
231
Device used to forward data around the internet.
(Endpoint Destination does not need to be connected to the router).
Router
232
Communication system where individual bits are sent one at a time
Serial
233
Communication in 1 direction only
Simplex
234
Connection device, usually at the center of a star network. Can learn computer addresses and only send data to the appropriate computer.
Switch
235
The way the computers are connected within a network
Topology
236
Utility used to display the path of a packet through the internet.
TraceRT
237
a type of system software designed to assist in managing, maintaining, and optimizing a computer system
Utility
238
MAC address example
00:1A:2B:3C:4D:5E
239
To manipulate data
Process
