Characteristics of the CPU
What are the common characteristics of the CPU?
- There are 3 common characteristics
- Clock speed
- Cache size
- Number of processor cores
- Each of these characteristics has a significant impact on the performance of the CPU
How do the characteristics of the CPU affect performance?
Clock speed
- The clock speed is measured in Hertz (Hz)
- The clock speed measures the number of fetch-decode-execute cycles that can take place in 1 second
- The faster the clock speed, the more instructions can be fetched and executed per second
- Modern computers have a clock speed in Gigahertz (GHz), meaning billion
- A clock speed of 3.5GHz can perform up to 3.5 billion instructions per second
Cache size
- Cache is very small, very fast memory on or close to the CPU
- Cache is used as temporary storage to provide quick access to a copy of frequently used instructions and data
- The larger the cache size, the more frequently used instructions or data can be stored
- This results in the CPU having to complete fewer fetch cycles from memory (RAM), speeding up the performance
- Cache also has a significantly faster read/write speed than RAM, making it much quicker to retrieve instructions from there instead of from memory (RAM)
Number of processor cores
- A processor core works like it is its own CPU
- Multiple core processors mean they have multiple separate processing units that can fetch, decode and execute instructions at the same time
- For example, a dual-core processor would have 2 processing units, each with their own
- Control Unit (CU)
- Arithmetic Logic Unit (ALU)
- Registers
- Multi-core processors can run more powerful programs with greater ease
- Multiple cores increase the performance of the CPU by working with the clock speed
- Example: A quad-core CPU (4 cores), running at a clock speed of 3Ghz
- 4 cores x 3GHz
- 4 x 3 billion instructions
- 12 billion instructions per second
- Example: A quad-core CPU (4 cores), running at a clock speed of 3Ghz
Worked example
1. State the purpose of the CPU |
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2. State what is meant by a dual-core 2.5Ghz processor |
[2] |
Answer
1. State the purpose of the CPU | [1] |
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2. State what is meant by a dual-core 2.5Ghz processor | [2] |
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