Architecture of the central processing unit (CPU): Difference between revisions

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  [[File:Exclamation.png]] This is an '''important concept'''.  You should fully understand this.
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[[File:binary.png|frame|right|This is a basic concept in computer science]]
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* Output exits the CPU via a bus
* Output exits the CPU via a bus


== Comparing CPU's ==
When we compare CPU's, we weigh a number of important factors, such as clock speed, number of cores, [https://en.wikipedia.org/wiki/Thermal_design_power tdp], socket type and class (desktop, laptop, mobile device).


But really, in a nutshell, it comes down to how much computing can be done when all parts of a CPU come together in a single clock cycle. If performing Task X takes two clock cycles on CPU A and one clock cycle on CPU B, then CPU B might be the better processor even if CPU A has a higher clock speed.<ref>https://www.makeuseof.com/tag/compare-different-cpus-right-way/</ref>


 
== A more advanced discussion of a CPU ==
These videos are truly superb to help you understand parts of a CPU, and how they work.
This is an excellent video discussing how a CPU actually works.  
 


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<iframe width="560" height="315" src="https://www.youtube.com/embed/FZGugFqdr60?list=PL8dPuuaLjXtNlUrzyH5r6jN9ulIgZBpdo" frameborder="0" allowfullscreen></iframe>
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These videos are truly superb to help you understand parts of a CPU, and how they work.




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'''Parts of a CPU:'''  
'''Parts of a CPU:'''  


# ALU - arithmetic logic unit, does arithmetic, comparisons using LOGIC
# ALU - The arithmetic logic unit executes all calculations within the CPU
# CU - control unit, coordinates how data moves around
# CU - control unit, coordinates how data moves around


'''Registers''',  a memory location within the actual processor that work at very fast speeds
'''Registers''',  a memory location within the actual processor that work at very fast speeds. It stores instructions which await to be decoded or executed.


# PC - program counter - stores address of the -> next <- instruction in RAM  
# PC - program counter - stores address of the -> next <- instruction in RAM  
# MAR - memory address register - stores the address of the next address or data of next instruction
# MAR - memory address register - stores the address of the current instruction being executed
# MDR - memory data register - stores the data that is to be sent to or fetched from memory  
# MDR - memory data register - stores the data that is to be sent to or fetched from memory  
# CIR - current instruction register - stores actual instruction that is being decoded and executed  
# CIR - current instruction register - stores actual instruction that is being decoded and executed  
# ACC - accumulator - stores result of calculations   
# ACC - accumulator - stores result of calculations   
# IR - interrupt register - manages requests from I/O devices


'''Buses'''
'''Buses'''
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# address bus - carries the ADDRESS of the instruction or data
# address bus - carries the ADDRESS of the instruction or data
# data bus - carries data between processor and the memory
# data bus - carries data between processor and the memory
# control bus - sends control signals memory read, memory write
# control bus - sends control signals such as: memory read, memory write


Together, these buses may be referred to as the “system bus” or the “front-side bus”  
Together, these buses may be referred to as the “system bus” or the “front-side bus”  
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[[File:Blank CPU diagram.png|caption|Can you fill this in?|225px ]]
[[File:Blank CPU diagram.png|caption|Can you fill this in?|225px ]]
* Describe the function of the ALU
* Describe the function of the control unit
* Describe the function of the program counter
* Describe the function of the clock
* Describe the function of an instruction
* Define instruction register
* What does a bus do?


== See Also ==
== See Also ==
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[[Category:computer organization]]
[[Category:computer organization]]
[[Category:Very important ideas in computer science]]

Revision as of 08:58, 6 March 2020

This is a basic concept in computer science

A central processing unit (CPU) is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions. [1]


Major parts of a CPU[edit]

Below we see a simplified diagram describing the overall architecture of a CPU. You must be able to outline the architecture of the central processing unit (CPU) and the functions of the arithmetic logic unit (ALU) and the control unit (CU) and the registers within the CPU.

Cpu diagram.png[2]


Please know and understand:

  • Memory holds both data and instructions
  • The arithmetic/logic gate unit is capable of performing arithmetic and logic operations on data
  • A processor register is a quickly accessible location available to a digital processor's central processing unit (CPU). Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only[3]
  • The control unit controls the flow of data within the CPU - (which is the Fetch-Execute cycle)
  • Input arrives into a CPU via a bus
  • Output exits the CPU via a bus

Comparing CPU's[edit]

When we compare CPU's, we weigh a number of important factors, such as clock speed, number of cores, tdp, socket type and class (desktop, laptop, mobile device).

But really, in a nutshell, it comes down to how much computing can be done when all parts of a CPU come together in a single clock cycle. If performing Task X takes two clock cycles on CPU A and one clock cycle on CPU B, then CPU B might be the better processor even if CPU A has a higher clock speed.[4]

A more advanced discussion of a CPU[edit]

This is an excellent video discussing how a CPU actually works.

These videos are truly superb to help you understand parts of a CPU, and how they work.


Do you understand this topic?[edit]

Outline the architecture of the central processing unit (CPU) and the functions of the arithmetic logic unit (ALU) and the control unit (CU) and the registers within the CPU.

Parts of a CPU:

  1. ALU - The arithmetic logic unit executes all calculations within the CPU
  2. CU - control unit, coordinates how data moves around

Registers, a memory location within the actual processor that work at very fast speeds. It stores instructions which await to be decoded or executed.

  1. PC - program counter - stores address of the -> next <- instruction in RAM
  2. MAR - memory address register - stores the address of the current instruction being executed
  3. MDR - memory data register - stores the data that is to be sent to or fetched from memory
  4. CIR - current instruction register - stores actual instruction that is being decoded and executed
  5. ACC - accumulator - stores result of calculations

Buses

  1. address bus - carries the ADDRESS of the instruction or data
  2. data bus - carries data between processor and the memory
  3. control bus - sends control signals such as: memory read, memory write

Together, these buses may be referred to as the “system bus” or the “front-side bus”


Can you fill this in?

See Also[edit]

References[edit]