TYPES OF PROCESSOR

Question 1

Describe how parallel processing would increase the performance of the computer system.

Answer 1

• Parallel processing allow multiple program instructions to be executed concurrently
• Different CPU cores can tackle different sections of a job simultaneously
• Longer rendering jobs can be split, increasing the speed of execution

Question 1

Describe what is meant by the term ‘RAM’

Answer 1

• Random Access Memory
• A form of primary memory
• Used to hold data and / or programs in use
• Volatile / loses its contents when power is lost

Question 1

Explain why GPUs are more suitable than CPUs for graphics processing

Answer 1

• CPUs are general purpose processors
• Whereas GPUs are coprocessors designed specifically for graphics
• They are parallel processors which are not well suited to general multitasking duties performed by the CPU
• And so likely to have built in circuitry / instructions for common graphics operations
• GPUs are able to perform and instruction on multiple pieces of data at one time
• Often we want to do this when processing graphics (e.g. transforming points in a polygon or shading pixels)
• Which means it can perform transformation to onscreen graphics quicker than a CPU

Question 2

Describe the differences between CISC and RISC architectures

Answer 2

• CISC has a larger instruction set
• RISC has a smaller instruction set
• CISC is difficult to pipeline
• RISC is easier to pipeline
• CISC tends to have more addressing modes
• RISC tends to have fewer addressing modes
• CISC instructions may take multiple clock cycles to execute
• RISC instructions take one clock cycle to execute
• RISC can only do complex tasks by combining multiple instructions
• CISC can do complex tasks in one line
• In assembly for CISC, a statement takes one mnemonic
• May take multiple mnemonics in RISC
• Some instructions in CISC will rarely get used
• In RISC instructions get used regularly
• CISC has more complex circuitry / more transistors
• RISC has less complex / simple circuitry
• CISC uses less RAM
• RISC uses more RAM as programs tend to be larger

Question 3

Describe the suitability of CISC and RISC for different devices

Answer 3

• RISC has smaller instruction set
• Requires fewer transistors / less complex circuitry
• Means less power is required
• No cooling
• Smaller battery
• Longer battery life

Question 4

Describe non-graphical uses for GPUs

Answer 4

• Performing complex numerical calculations
• Calculations on matrices / vectors / multiple data at the same time

Question 5

Give examples of uses for the GPU

Answer 5

• To render models
• Run CAD software
• Run modelling calculations

Question 6

Explain the effect of using a co-processor for:
Complex calculations for scientific research
Printing personalised letters

Answer 6

• Calculations are done by the maths co-processor
• So processing is faster
• When using floating point arithmetic
• No increase in speed
• As co-processor not suitable for task / as there are no calculations

Question 7

State the differences between RAM and ROM

Answer 7

• RAM is volatile / ROM is not volatile
• RAM is read and write (editable) / ROM is read only (cannot be altered)
• RAM is larger / ROM is smaller

Question 8

State what is stored in RAM and give a reason why it is used

Answer 8

• User files / programs / OS currently in use
• User must be able to alter contents of the file / computer needs access to the software but needs to be able to replace it
• RAM offers direct access
• RAM operates at a much faster speed than most secondary storage devices

Question 9

State what is stored in ROM and give reason why ROM is necessary

Answer 9

• Bootstrap / BIOS
• Must be available when the computer switched on (therefore must be stored on medium which is non-volatile)
• The bootstrap / BIOS must not be deleted / unintentionally amended ( and therefore is best stored on a read-only medium)

Question 10

Explain the advantages of storing an operating system on ROM

Answer 10

• ROM is quick to start up so the system can be started up quickly
• ROM cannot be altered so there is no change of the OS being accidentally or maliciously changed

Question 11

Discuss the different approaches that can be used to provide increasingly larger amounts of computing power and the types of problem they are suited to

Answer 11

• Processors have increasingly large clock speeds and can be overclocked
• Processors can have multiple cores
• Supercomputers can have multiple processors (and GPUs)
• GPUs can be applied to problems other than graphics processing
• Problems can be distributed across a number of computers working together
• Having multiple cores can speed up smaller problems but this will not be enough for larger problems
• Supercomputers are prohibitively exceptionally expensive to buy and run for all but large organisations
• GPUs are becoming a cost efficient way of tackling problems
• GPUs tend to have large number of cores so can run on highly parallelisable problems
• But only where the same instruction is being applied to multiple pieces of data (SIMD)
• Increased clock speed is limited to smaller problems
• Even doubling the clock speed would only halve the time taken
• Parallel Processing isn’t suited to all problems
• Most problems are only partially parallelisable
• Writing algorithms for parallel processing is more challenging than GPUs
• GPUs suited to a subset of science / engineering problems where the same calculation is repeated on multiple data sets

Question 12

Other than the maths co-processor, state other types of coprocessors and describe why they may no longer be used

Answer 12

• I/O coprocessors in mainframe systems
• Coprocessors managing network operations (NPUs)
• Many of the examples are now obsolete as CPUs have become more comprehensive and functionally more comprehensive

Question 13

What is a coprocessor

Answer 13

Any additional processor used for a specialised task