1.1.1 - The factors affecting the performance of the CPU, Pipelining

Question 1

What are the main factors affecting processor performance?

Answer 1

• Clock Speed
• Number of cores or duplicate processors
• Amount and type of cache memory

Question 2

What is clock speed?

Answer 2

The speed in which the system clock switches between 0 to 1 and back to 0.

Question 3

What is clock speed measured in?

Answer 3

Gigahertz (GHz) which is 1 billion cycles per second.

Question 4

What is an average clock speed for a PC?

Answer 4

Between 2 and 4 GHz. The higher the clock speed the quicker the instructions will be executed.

Question 5

What is cache memory?

Answer 5

Very fast and expensive memory inside the CPU.

Question 6

What is cache memory used for?

Answer 6

When an instruction is fetched from main memory it is copied into the cache incase it is needed again soon after. After the cache fills up unused instructions are replaced by more recent ones.

Question 7

What are the different levels of cache and what are fastest?

Answer 7

• Level 1 cache. Extremely fast but small (2-64Kb)
• Level 2 cache. Fairly fast and medium sized (256Kb-2MB)
• Some CPUs also have Level 3 cache.

Question 8

What is pipelining?

Answer 8

A technique that allows the next instructions to be fetch at the same time as the processor is performing arithmetic or logic operations.

Question 9

Words and Word Sizes

Answer 9

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