2023 Paper Flashcards
Explain why virtual storage is well suited for backups
• Allows a section of hard drive to be freed to act as RAM
• Backups not currently being used can be stored in that RAM through paging freeing up memory for other programs in RAM
Advantages of LAN networks
• Easier to setup the network in a local area
• Inexpensive compared to a Wide Area Network
• Faster communication speeds between networks in a small geographical area
Explain what is meant by a network protocol
• A network protocol is an established set of rules that determine how data is transmitted between different devices in a same network
What two protocols may be used in a LAN
• File transfer protocol
• TCP/IP
Explain why protocol layering is used
• Layers each have defined responsibilities and are ordered
• So data moves from one layer to next from application to point where it can be transmitted across a network
• Allows communication systems to be as open as possible.
Give the names of three operating systems and state it’s purpose for each
• Distributed OS is where load is distributed across the OS to reduce time handling tasks.
• Embedded OS performs a small range of specific tasks catered towards a specific device.
• Multitasking OS enables the user to carry out tasks appearing simultaneously by using time slicing to quickly switch between applications and programs in memory.
Explain how an OS deals with an interrupt
• FDE cycle stops and processor saves current tasks ongoing
• Special registers on processor saved onto stack.
• Processor focuses on interrupt and depending on quantity of interrupts the interrupt handler will place them on a queue
• Processor loads Interrupt Service Routine into RAM and sets a flag signal to start ISR.
• After interrupt is serviced flag is reset and ISR repeats for any more interrupts.
• Contents of stack is transferred back onto registers and FDE cycle resumes.
Explain how an OS can manage the memory available to applications and why doing so is important (9)
• An OS can manage memory available to applications by storing frequently used applications and programs into RAM which loads up these saved applications faster increasing efficiency of OS
• Paging can split up memory into 4K chunks increasing efficiency for organisation of memory in program.
• This then can be swapped between main memory and hard disk when needed.
• Segmentation can be used where memory is split up into sizes which can vary representing the logical flow of the program.
• Virtual memory can be used where the section of the hard drive acts as RAM to shore programs being used when spaces in memory is insufficient.
• Sections of program not currently being used is temporarily moved into virtual memory through paging.
• Memory management important to organise data in an Os to improve performance and efficiency while freeing up space ensuring blocks of memory space are managed to prevent data loss.
Describe one difference between a stack and a queue
In a stack the last element to be added is the first to be removed (FILO) whereas in a queue the first element added is the first to be removed (FIFO)
Describe one difference between an array and a list
A list can consist of elements of multiple data types but an array consists of elements of the same data type
How is a tuple different to a list
A tuple cannot be changed but a list can be changed
Describe how the second item in a linked list would be accessed using pointer values
• The counter variable needs to be set to 0
• The local pointer variable should be pointing to the first node in the list
• If pointer = NULL then it’s the last node on the list
• If local and main pointer = NULL list is empty
Describe two differences between assembly language and high level languages
• Assembly languages uses an assembler to convert instructions into machine code and is machine specific which the processor directly understands
• A high level language is easier to learn and use accepting the input of strings closer to human language then turns this into binary behind the scenes providing abstraction
Compare the robots use of encryption and hashing for storing and communicating data (9)
• Encryption is the process of scrambling data before sending it and decrypts data upon arrival. Hashing is the process of turning a string of characters into a fixed size value using hash functions which cannot be reversed.
• Symmetric encryption is where both sender and receiver use one key to encrypt and decrypt data and this one private key must be protected to prevent interception from third parties.
• Asymmetric encryption is where both sender and receiver uses two keys to encrypt and decrypt data. Public key is used for encryption and private key is used for decrypting. Keys work as a pair and one robot can communicate using encryption as well as a user while another robot can decrypt the data or a programmer to ensure smooth connection sending messages with security. Private key helps verify sender’s identity through digital signatures.
• Hashing can be used to store passwords across the wireless network by hashing the user’s password and compares it to the stored key for authentication and prevents unauthorised access to passwords that can interfere with robot communication.
• Hash tables are appropriate since it’s used in databases and can store a large amount of information about multiple humans in this context.
• Encryption is used by the robot so data/messages is effectively and safely communicated between robots wirelessly and hashing is used so user’s passwords are protected across wireless network which prevents interception of confidential data providing security for robots.
Programmers do not want other people to download and use these images. State name of one piece of relevant legislation and describe it
Legislation: Copyright, Design and Patents Act 1988
Description: Protects people’s property online and the copyright automatically applies for original work
Programmers need to use images they have not created. Give ways to make sure images used legally:
• Ask for permission to use these images from owner
• Buy the patent/license
