1.1.2 CPU Performance

Today's Knowledge

- Clock Speed

- Cache Size

- Number of Cores

 

What you need to know:

Cores

-        A core acts as an additional processing unit (basically a CPU on a CPU)

-        A core contains an ALU, control unit and registers

-        CPUs with multiple cores have more power to run multiple programs at the same time.

The CPU with six cores will have more power to run multiple programs at the same time than the quad-cord does, so you could say that the six-core processor is the more powerful computer… Although other factors such as clock speed, RAM and cache also play a massive factor to the overall outcome of a PCs performance.

 

 

Clock speed

-        Is measured in Mhz (megahertz) or Ghz (Gigahertz).

-        Indicates the number of fetch-decode-execute cycles the CPU can perform in a second.

-        1(Ghz) CPU is doing 1 billion cycles per second. 3(Ghz) CPU is doing 3 billion cycles per second.

-        You can increase a CPU clock speed, which will make your computer run faster - this is called overclocking.

 

 

 

Cache (Static Random Access Memory)

-        Cache stores copies of data and instructions from memory that is waiting to be used by the CPU.

-        It holds common data that it thinks the CPU is going to access over and over again.

-        It is faster to transfer to and from cache than transferring data to and from the RAM.

-        The greater the cache you have, the more instructions can be stored, the faster your computer can perform.

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1.1.1 Systems Architecture

Today's Knowledge

 - The Purpose of the CPU

- Common CPU components and their functions

- Von Neumann Architecture

What you need to know:

1.1.1 Fetch Decode & Execute Cycle.

The fetch-decode-execute cycle describes the basic operation

of modern computers.

 

Fetch

-        Instructions are loaded into the RAM (main memory)

-        Each instruction is then fetched from main memory (in order)

 

Decode

-        The instruction is then decoded (works out what it needs to do)

 

Execute

-        The decoded instruction is then executed (carried out)

-        Examples of an instruction can be… performing a calculation. Storing information back into RAM 

Related topic:

Clock speed:  3Ghz CPU = 3 billion (FDE) cycles per second

Common CPU components and their function & Von Neumann Architecture:

ALU (Arithmetic Logic Unit)

Performs calculations and logical decisions.

Manages: Arithmetic and logical operations, calculations and comparisons.

 

CU (Control Unit)

Sends signals to other components controlling how data moves around the CPU.

Manages: The instructions            Controls:  The other components

 

Cache

Stores and provides fast access to frequently used instructions and data.

 

Registers (high speed memory that helps the control of data around the CPU)

Program Counter (PC): Stores the address of the next instruction to be run.

Memory Address Register (MAR): Stores the address of where data is fetched from.

Memory Data Register (MDR): Stores the data that is fetched from main memory.

Accumulator (Acc): Stores the results of the calculation.

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