YEAR 1 CO1 WEEK 5 FACTORS AFFECTING PERFORMANCE OF CPU Flashcards
What is clock speed and how does it relate to a computers performance?
CPU is a sequential machine so carries one instruction at a time in order.
To coordinate this it has a internal clock which runs at certain speeds which indicates how fast a CPU can run.
What is clock speed measured in and what does it indicate?
Measured in megahertz (MHz) or gigahertz (GHz) and corresponds to how many instruction cycles the CPU can deal with in a second.
(A 4 GHz CPU performs four billion cycles a second.)
How does clock speed relate to heat generated and how can this be mitigated?
Every time clock ticks it uses up power which causes heat to be produced.
Faster CPU = more heat produced.
A Heat Sink needed to keep temperature as low as possible.
What is overclocking?
Where some people increase CPU clock speed to try to make their computer run faster.
Possible to change max CPU clock speed in BIOS settings.
What is a core?
A Complete processing unit within the CPU having an ALU, CU and registers.
What are the ways cores can improve performance of a computer?
Parallel Processing where a task or problem is split up across all the available cores so each core tackle part of the overall problem. (In theory doubles or quadruples performance.)
Multitasking where multiple tasks can be performed at the same time
e.g. each core handles a seperate piece of software.
Does increasing number of cores increase performance?
Doubling number of cores doesn’t necessarily double computer speed as this extra speed is used up when they communicate between eachother.
What is cache and state its purpose.
Cache is small volatile memory stored closer to CPU than RAM which temp stores data and instruction frequently used.
How does cache improve computer performance?
As it is closer to the CPU than RAM it automatically checks first whether it has the data needed as it is a lot quicker to access saving time having to request data from RAM.
What are the different grades of cache?
L1 part of the CPU itself both being the smallest but fastest to access.
Each level the cache gets larger but slower to access.
More L2 and L3 memory available the faster the computer can run.
What is ROM?
Read Only Memory which stores a limited number of instructions or data not meant to be changed.
Very useful for things like storing BIOS settings which are not meant to be changed being the recommended settings by manufacturers as well as storing instructions relating to setting.
Read Only, non-volatile and random access.
What does memory do?
Stores data and instruction.
What is RAM and state its function.
Random Access Memory is used to temp store data and instruction being used by the current program running.
The phrase ‘Random’ means that data and instruction can be read from or written to any part of the memory.
Why is RAM needed?
As there is a huge gap in the speed of CPU processing data extremely fast vs hard disk slow to access, RAM acts as a temp storage space inbetween these two.
How does more RAM increase computer performance?
More instructions/programs held in RAM and run at same time.
Software responds faster.
Can run more memory intensive software.
Reduces use of Virtual memory.
Less use of Hard Disk which slower to access.
