Year 9 CPU architecture

• Computing
• Upper Secondary (Key Stage 4)
• Lower Secondary (Key Stage 3)

Year 9 Computer architecture

Log into your student accounts and go to the following website

www.lessonup.app

the code is written on the whiteboard.

Log into your student accounts and go to the following website

www.lessonup.app

the code is written on the whiteboard.

What is binary?

What is a computer?

What is an input device?

What is 9 in binary?

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Learning intension

By the end of this lesson will know what the architecture of the CPU looks and functions like.

Create a PowerPoint drawing of the CPU diagram caption it with your own words to help you remember what these things are.

The Central Processing Unit or CPU is arguably the most important component of a computer​

What does it do?​

What organ in the human body ​

is it often compared to?​

What are the similarities it has ​

to this organ?​

                         The CPU processes instructions​

• When you run a program, it is the ​CPU which runs the instructions​.
• It is often thought of as being ​the ‘brains’ of the computer​.
• The way that a brain works is ​very different to a CPU​.
• A CPU simply runs one ​simple instruction at a time​.
• It carries out billions of ​instructions per second​.

Essentially this means anything to do with a computer process is stored in the same box meaning memory.

The CPU accesses both instructions and data from the ​

same RAM.

The CPU has two major components 

• The​ Control Unit 
• Arithmetic-Logic Unit (ALU)​.

These connect to the memory unit inside of the CPU chip.

Inside the memory unit is registers and cache memory, these are used to carry out instructions. ​

• A register is a very fast ​memory location in the ​CPU.
• Cache is located on the CPU, it is slower to access than ​registers but faster than RAM​.

Write down what you have learned so far.

There are three logical operations what are they?

The ALU or Arithmetic Logic Unit is where the actual arithmetic operations are done​.

It also carries out logical operations such as those including AND, OR and NOT​.

CPU Registers

• Program Counter (PC) ​- holds the address of the next instruction to be executed​.
• Memory Address Register (MAR)​ - holds the memory address of the current instruction, and then the data that it uses, so that these can be fetched from memory​.
• Memory Data Register (MDR)​ - holds the actual instruction, and then the data that has been fetched from memory.​
• Accumulator​ (ACC) - holds the result of an instruction before it is transferred to memory​.

Von Neumann architecture uses the ‘stored program’ concept.
What does this mean?

Used for temporarily storing arithmetic and logic results. 

Points to the next instruction that needs to be executed. It is located in the Control Unit 

Used for holding the address of the

current instruction to be executed,

and the address of data to be used in instruction 

Used for holding the actual instruction or data that is stored in RAM. 

MAR

MDR

ACC

PC