1.1.2 CPU Performance Flashcards
True or False: The clock speed of a CPU is measured in Hertz (for example, 1.8GHz)
True
What is the name of the cycles that the CPU completes? (Each cycle is where the CPU carries out one instruction.)
Every time a CPU completes an instruction is called a Fetch-Execute cycle.
What does the Control Unit do?
The Control Unit includes the Program Counter, which organises and holds all the next instructions and memory addresses, so that the instructions are managed and run in order.
True or False: The cache (sometimes also known as the Immediate Access Store) is contained within the CPU.
True
What is the third common characteristic that affects CPU performance, if the first two are clock speed and cache size?
Number of cores
Why does the cache affect the performance of the CPU?
The cache affects the CPU performance because data for instructions can be accessed quicker, by the CPU, than if the data was stored in RAM (which is slower). The CPU is not slowed down by having to go to the RAM.
True or False: Having more cores always makes the CPU run faster.
False. It usually does, but sometimes it will depend on the order or priority that the instructions need to be completed in. For example, one task might need to wait for another to be completed, so it can’t be sent to another core.
True or False: The clock speed is the number of fetch-execute cycles that can be completed in one second.
True. A 1.8 GHz (gigahertz) CPU processes 1.8 billion cycles per second.
Which CPU would run faster, a 1.8GHz or 1.2GHz?
1.8GHz. They are both gigahertz (GHz) and 1.8 is bigger than 1.2.
Which is a bigger memory store, 128Kb or 128Mb?
128Mb, because M (mega) is 1000 times a K (kilo) byte.
Which writes and reads data faster: cache memory in the CPU or memory in the RAM?
Cache memory is faster to write and read data and instructions than RAM.
True or False: Each core in a CPU can process data and instructions independently of the rest.
True.
True or False: Computer chip manufacturers made multi-core processors because they could not make CPUs run any faster.
True.
How many instructions can be executed per second by a 3.5GHz CPU?
3.5 billion.
Why does doubling the number of cores in the CPU not necessarily increase the speed of executing instruction by two?
Instructions may have to be executed in order, or according to a priority, so not all instructions can be shared between the cores; sometimes they have to wait for others.
Also, sometimes software has not been designed to use multiple cores.
