Model answers for ppq

How is a character set used to store a word

• unique binary/denary value allocated to each character

• Code for each character stored in sequence/order

How does increasing sample resolution increase quality of recording

• More bits for each amplitude

• Amplitudes more precise

• Wider range of amplitudes recorded

Increasing cores improves performance

• More FDE cycles executed each second

• …because each core runs one FE cycle, allows instructions to be carried out simultaneously

More cache improves performance

• More cache means processor can access more frequently used data/instructions faster

• … instead of having to access data from slower-access RAM

Purpose of virtual storage

Run programs when there is insufficient RAM to run them

Managing memory (operating system)

• Allocates memory to processes

• Prevents two processes from accessing the same memory

Managing peripherals (operating system)

• allocates data to buffers

• Transmits data to hardware

• Receives data from hardware

Purpose of interrupt

Indicate that something requires the attention of the CPU/processor

How programs manage current process and interrupts

• Interrupt is given priority and placed in interrupt queue

• Processor finishes current FDE cycle for program

• Processor checks interrupt priority queue // checks for higher priority interrupt than program

• If interrupt has lower priority, program runs next FDE cycle / continues with program

• If higher priority, processor stores current process on stack

• Checks source of interrupt and calls ISR

• ISR handles interrupt

• Repeats if there is another higher priority interrupt

• Retrieves content from stack to continue process

Software

Instructions/program that is used to operate a computer

Operating system

Software that manages inputs and outputs for the computer

File compression

Reducing size of a file

Benefit of compression

Take up less storage space

Why a device needs ROM

• Stores BIOS

• Starts bootstrap

• Store start up instructions

• Store data permanently

Cloud storage

• Collection of servers

• Store data in remote location

• Hardware managed by third party

• Data accessed using internet

Benefits of using cloud storage

• No need to maintain hardware

  • Third party responsible for maintaining hardware

• Need less storage on watch

  • Watch can remain small

  • Cost of watch kept lower

• Can access data from other devices

  • If watch breaks, data still available

Watch = embedded system

• Can only perform dedicated function

  • General purpose performs many functions

• Can’t plug in peripherals

• Can’t reprogram

• No CPU (only microprocessor)

Barcode scanning - check for errors

• Check digit calculated from barcode data

  • Using algorithm

  • And digit is added to barcode

• When barcode is scanned, check digit recalculated

  • Using same algorithm

• If check digits don’t match, error occurred

Data errors after transmission

• Data can be lost/gained/added (changed)

• Bits reassembled in wrong order

• Interference

• Hop count

Robot uses machine learning

• gather data

  • Learn/adapt its own process

  • Learn from mistakes

  • Choose most efficient method

  • Learn where … placed, what not to do

Run length encoding

• Store consecutive pixels of same color and number of repetitions

Break down file + transmission

• fixed size packets

• Header - IP addresses

• Payload - actual data

• Trailer- error checking

• Router directs packet to destination, most efficient route

• Each packet takes different route, arrive out of order

• Once last packet arrives, reordered

CPU purpose

• Carry out FDE cycles

• Process instructions & data to produce output

Lang. for processors

• clock speed

• More FDE per second

• More instructions executed per second

Embedded system features

• dedicated function

• Dedicated hardware

NIC purpose

• provide MAC address to computer

• Receive data from network, convert to be understood by computer

• Convert data from computer to be transmitted over network

• Allow physical connection between computer and network

HTTPS process

• Uses ssl

• Encrypts data, asymmetric encryption

• Data encrypted with web servers public key, only decrypted with web servers private key

• Data transmitted to server can only be decoded by server

AI characteristics

• Collection of data

• Rules for data

• Ability to reason

• Ability to adapt

Search engine machine learning

• Change data and rules according to feedback

• Supervised/unsupervised learning

• Use ranking algorithm to decide what appears first

Interpreter advantage

• each statement translated and executed before next, stops when error found

• Can correct and continue from where stopped

• No need to retranslate all of code again

• Can test sections of code without all of program being functional

Analogue sound to digital

• Record w/ microphone

• Sample sound wave

• Measure amplitude - each has unique binary value

• Sample rate set

• No. Samples per second

• Set sample resolution

• No. Bits per sample

• Each sample converted to binary

Software

Program used to operate hardware

Symmetric encryption

• Plain → cipher text

• Encrypted with algorithm - uses key

• Key generated with algorithm

• Key transmitted to receiver

• En + de with same key

Firmware

Allow communication with hardware