1
Q
What is a CPU?
A
A CPU processes and executes instructions that are input to the computer so that the result can be output
2
Q
What is a microprocessor?
A
An integrated circuit on a single chip
3
Q
What are the 2 types of units?
A
- Arithmetic Logic Unit (ALU)
- Control Unit (CU)
4
Q
What is the function of the ALU?
A
- carries out all mathematical & logical operations (e.g. AND, OR, NOT and binary shifts)
- Stores interim values in the ACC
5
Q
What is the function of a control unit?
A
- Coordinates all CPU actions in the F-D-E cycle and decode instructions
- sends and receives control signals to fetch & write data
6
Q
What are registers?
A
High speed volatile memory components that temporarily store data in the CPU
7
Q
What is program counter (PC)?
A
Stores the memory address of the next instruction to be fetched
8
Q
What is MAR?
A
Stores the memory address of the instruction that is about to be fetched from RAM
9
Q
What is MDR?
A
Stores the instruction/data that have just been read from RAM
10
Q
What is CIR?
A
Stores the instruction that is currently being decoded and executed by the CPU.
11
Q
What is ACC?
A
Stores any interim values created during ALU calculations
12
Q
What is the control bus?
A
sends & receive signals that controls the CPU and other parts of the computer system (bidirectional)
13
Q
What is the address bus?
A
carries the memory address (unidirectional from CPU to RAM)
14
Q
What is the data bus?
A
Carries the actual binary data (bidirectional)
15
Q
Explain the fetch in FDE cycle
A
- PC holds the memory address of the next address to be fetched
- memory address is copied to MAR and copied to RAM all via address bus
- RAM uses the address to locate the data/instruction that must be processed
- Instruction is copied and sent to the MDR via the data bus
- The MDR copies the instruction to the CIR
- PC increments
16
Q
Explain the decode in FDE cycle
A
The CU decodes the data/instruction using instruction sets
17
Q
What are instruction sets?
A
A predefined list of commands that can be processed by a CPU and is machine specific
18
Q
What do instruction sets consist of?
A
OPCODE - commands (e.g. ADD, MUL)
OPERAND - the data being operated on/location of where the operation is to be performed in
OPERATOR - mathematical operators
19
Q
Explain the execute in FDE cycle
A
- The ALU carries out arithmetic & logical operations, storing interim values in the ACC
- Instruction is executed and the cycle repeats
20
Q
What is stored program concept? (General-purpose systems)
A
a computer that stores instructions and data together in the same memory
21
Q
Why is stored program concept better than fixed program concept?
A
- flexible; can be reprogrammed for new tasks whereas fixed is limited
- can store and execute multiple programs
22
Q
CPU internal clock and what is it measured in?
A
- Controls the synchronization and number of FDE cycles completed per second
- Measured in Hertz (Hz)
23
Q
Effect of overclocking?
A
- unsynchronisation of data which can cause a crash
- overheating
24
Q
What is a core?
A
A core is a single processing unit that performs FDE cycle
(multi-core processors can run multiple FDE cycles at the same time)
25
What is cache memory?
High-speed volatile memory built inside the CPU and can be accessed faster than main memory and stores frequently used programs.
26
Effect of higher cache? (good & bad)
- faster access to data & instructions (better CPU performance)
- extremely large cache would take more time to look through while fetching information so it can slow down the search process (a limit is set)
27
What are embedded systems?
A system that carries out a specific function
28
Advantages of embedded systems
- small & easy to fit
- Cheap and easy to make
- consumes little power
29
Disadvantages of embedded systems
- susceptible to hackers
- difficult to update
- limited processing resources
30
Compare embedded systems with general purpose systems
- embedded is slow // general is fast
- one purpose whereas general is multipurpose
- embedded is very reliable whereas general may have bugs in certain softwares
- programs stored on ROM whereas general purpose systems has programs stored on hard drives
31
Examples of embedded systems?
● domestic appliances
● security systems
● lighting systems
● vending machines
32
Acoustic sensor and uses
detects sound levels in an environment
security systems
33
Accelerometer sensor and uses
detects sudden movements and measure tilt/orientation
mobile phones, change in vehicle movement
34
flow sensor and uses
the amount of fluid flowing through an environment
monitoring gas flow in pipes
35
gas sensor and uses
detects amount and conc. of gases
carbon monoxide detectors
36
humidity sensor
measures the humidity levels in an environment
37
infra-red sensor and uses
detects infrared radiation and motion from objects
security systems
38
level sensor and uses
level of fluids
monitor petrol levels in cars
39
light sensor and uses
detects light levels of an environment
street lights automatically switching on
40
magnetic field sensor and uses
detects changes in magnetic field
anti-lock braking systems
41
Moisture sensor and uses
measures moisture levels in solids
checking moisture levels for farms
42
pH sensor and uses
measures the pH level of a substance
monitor soil acidity & water for pollution
43
proximity sensor and uses
detects how close an object is to the sensor
automatic doors
44
pressure sensor and uses
detects pressure exerted on an object
tyre pressure, security systems
45
temperature sensor and uses
measures environmental temperature
regulate central heating system/cooling system
46
What is a Network Interface Card?
a hardware component that connects a computer to a network, allowing it to communicate and share resources.
47
First 3 pairs of hex digits in MAC address is?
The Organizational Unique Identifier (OUI)
48
Last 3 pairs of hex digits in MAC address is?
Serial number
49
Role of router in a network (3)
- routes data packets between different networks
- assigns static private IP addresses
- connect LAN to WAN
50
What is a static IP address?
An IP address that doesn't change and is manually set on the device assigned by a router (easier to track, less secure)
| Routers and DHCP assigns private IP, ISP assigns public
51
What is a dynamic IP address?
IP address that changes each time the device connects to the network and is assigned by DHCP (harder to track, more secure)
| Routers and DHCP assigns private IP, ISP assigns public
52
What is cloud storage?
Data stored on 3rd party remote server accessible via the internet
53
Advantages of cloud storage
- accessible everywhere only with internet
- data backed up automatically
- easy to increase/decrease storage
54
Advantages of local storage
- full control over data
- safer if the device is physically secure
- one-time hardware cost
55
Disadvantages of cloud storage
- data may be hacked/misused
- can't access files without the internet
- may need to pay subscriptions
56
Disadvantages of local storage
- data only accessible on the same device
- risk of data loss
- changing storage size may be difficult
57
Virtual memory
An extension of the primary storage located in the secondary storage when RAM is full
58
What happens when RAM is full?
- Data is divided into pages and pages not current used by the cpu are moved to virtual memory
- this frees up space in RAM so it can load new data
- when required they are moved back (paging)
59
Purpose of virtual memory (3)
- to extend RAM capacity
- to prevent the computer from crashing when RAM is full
- to allow computers to process large amounts of data
60
What is primary storage
storages that contain data that can be directly accessed by the CPU
61
RAM characteristics
- holds the instructions that are currently in use
- volatile (loses its contents when switched off)
- allow read/write operations
62
ROM characteristics
- non-volatile and permanent
- read only
- stores the BIOS and bootstrap
63
What is secondary storage
storage that contains data that cannot be directly accessed by the cpu
64
What are the 3 types of secondary storage
- magnetic storage
- optical storage
- solid state (flash memory)
65
How does magnetic storage work?
- Uses circular platters divided into concentric tracks and sectors (allows simultaneous read/write operations)
- electromagnetic read/write heads magnetizes(1s) and demagnetizes(0s) spots whilst the disk is spinning
66
Example of magnetic storage
Hard disk drive (HDD)
67
How does optical storage work?
- Uses circular discs and lasers
- disc is spun with a read/write head over it which uses a laser beam
- laser burns pits (1s) and lands (0s)
- is read using a sensor processing the reflection of the pits and lands
68
Examples of optical storage
CDs, DVD, Blu-rays
69
How does solid-state (flash memory) work?
- Transistors & cells are arranged on a semi-conductor chip in a grid pattern
- uses NAND and NOR technology
- electrons are trapped in transistors to story binary data electronically
70
Example of solid-state (flash memory)?
- SSD
- USB Flash memory
71
Advantages and disadvantages of magnetic storage
- Cheaper per GB
- high storage
- reusable & rewritable
____________________________________
- not as portable
- noisy and generate heat
- moving parts can fail
72
Advantages and disadvantages of optical storage
- Portable
- Small
- low cost per GB
____________________________________
- low storage capacity
- easily scratched/damaged
- slower read/write speeds
73
Advantages and disadvantages of solid-state
- very fast read/write speeds
- silent
- portable and small
- no moving parts
- durable
________________________________________________
- more expensive per GB
- limited write cycles
- can wear out over time
74
characteristics of embedded systems
(name 3)
- performs a dedicated function
- it has dedicated hardware
- uses firmware
- doesn't require much power
- cheap to manufacture
- small in size
