3. Hardware Flashcards
1
Q
FDE cycle
A
- PC contains the address of the next instruction
- Contents of the PC are copied to the MAR
- PC is incremented by 1
- Address bus carries the value in the MAR to RAM
- Control bus sends a “read” signal to RAM
- Data bus carries the contents of the desired RAM address from RAM to the MDR
- Contents of the MDR is copied to the CIR
- CU decodes the instruction in the CIR (opcode = what the instruction is, operand = what to do it to)
- The instruction is sent to the ALU to be executed
- ALU may use the ACC to temporarily store its results
2
Q
Purpose of a core in the CPU
A
- to process/execute instructions, OR
- to perform a fetch-decode-execute cycle
3
Q
Role of a register in the CPU
A
- to store/hold data/address/instruction
- …temporarily
4
Q
Embedded system
A
- built into a device
- has a single purpose/dedicated function
- runs on firmware
- does not have additional peripherals
5
Q
Microprocessor
A
- type of integrated circuit
- on a single chip
6
Q
Opcode
A
the operation to be performed
7
Q
Operand
A
the location where the operation is to be performed/the data to be operated on
8
Q
Virtual memory
A
- the hard drive is partitioned to create virtual memory
- when RAM is full
- …pages of data that are not required
- …are transferred from RAM to virtual memory
- when the data is required again the pages are transferred back to RAM
9
Q
Purpose of RAM
A
- volatile storage
- stores data for the CPU to access quickly/directly
- stores currently running data/instructions
10
Q
Why a computer needs ROM
A
- to store data permanently
- to store the instructions to start up the computer
- to store the BIOS (Basic Input Output System)
11
Q
Features of magnetic storage
A
- data is stored on platters
- (platters) are divided into tracks and sectors
- has components that are spun
- data is read/written using a read/write arm
- data is read/written using electromagnets
- magnetic field determines the binary value
- non-volatile
12
Q
Features of solid-state storage
A
- flashes data onto chips
- uses transistors
- uses NAND/NOR technology
- uses control gates
- controls the flow of electrons
- volatile or non-volatile
13
Q
Features of optical storage
A
- laser is shone at the disk and reflection is processed
- arm moves the laser across the surface of the disk, and the laser is also used to read data from the pits and lands
- when the laser hits the point where the pit changes into a land or vice versa the light scatters and is not reflected back as well
- this is captured by a sensor and can be interpreted as a change in the binary value
- non-volatile
14
Q
Cloud storage
A
- a collection of servers
- …that store data in a remote location
- …that are often maintained/backed up by a third-party company
- …that are accessed using an internet connection
15
Q
Advantages of cloud storage
A
- data can be accessed from any computer, but an internet connection is required
- capacity is added very quickly by upgrading a subscription
- initial costs lower, but monthly fees charged per tebibyte (TiB)
- some cloud providers add other features, e.g. ability to collaborate on shared documents
16
Q
Disadvantages of cloud storage
A
- always slower than local storage even with a fast internet connection
- risk from unauthorised access, risk of hardware failure in data centre
- data stored remotely, maybe in a different country (could be subject to different privacy laws). backups are the responsibility of the cloud provider
- environmental concerns about energy use of data centres which operate 24/7
17
Q
Features of MAC addresses
A
- unique address
- assigned by the manufacturer
- can be used to identify a device
- contains the manufacturer ID
- contains the serial code
- written in hexadecimal
- has 6 bytes/64 bits
- does not (usually) change/is static
18
Q
Characteristics of IPv4
A
- denary based
- …with numbers between 0 and 255
- 32 bits
- 4 sets/groups of numbers
- …separated by dots
- it is a unique address
- can be static or dynamic
- can be public or private
- contains the network prefix
- …and the host number
19
Q
Characteristics of IPv6
A
- hexadecimal based
- …with values between 0 and FFF
- 128 bits
- 6 sets/groups of digits
- …separated by colons
- it is a unique address
- can be static or dynamic
- can be public or private
- contains the network prefix
- …and the host number
20
Q
Differences between IPv4 and IPv6
A
- IPv4 has 32 bits while IPv6 has 128 bits (not 64!)
- IPv4 is written in denary, IPv6 is written in hexadecimal
- IPv4 is separated using dots, IPv6 is separated using colons
- IPv4 has 4 groups of digits, IPv6 has 8 groups of digits
- IPv4 has digits between 0 and 255, IPv6 has digits between 0000 and FFFF
- IPv4 all 0s are displayed, IPv6 can use double colons to replace repeated groups of 0000
- IPv4 has fewer available addresses, IPv6 has more
21
Q
Dynamic IP address
A
- can be used to uniquely identify a device on a network
- it can change
- …each time the device is connected to the network
22
Q
Router
A
a device that forwards packets to their correct destinations in a network
23
Q
Network interface card (NIC)
A
a component in a device that enables it to connect to a network
24
Q
Tasks carried out by a router
A
- send and receive packets of data
- connect a local network to the internet
- assign IP addresses to nodes/devices
- convert packets from one protocol to another
