Lesson video

Hello, I'm Mrs. Jones and I'm really pleased that you are here to learn with me today.

In this lesson, we will look at system architecture and how the processor works within this.

So let's get started.

Welcome to today's lesson.

Today's lesson is called The Processor from the unit: Computer Systems. And by the end of this lesson, you will be able to explain the purpose of the CPU in a computer system and describe the individual characteristics of its components.

There are four keywords to today's lesson: computer architecture.

Computer architecture is the design of a computer system.

Control unit.

Control unit controls the instructions and other components in the processor.

Arithmetic logic unit, ALU is the calculator in the processor used to handle mathematical and logical operations.

And registers.

Registers: a selection of registers that are very small and fast memory locations in the processor.

There are two sections to today's lesson.

The first is define the von Neumann architecture structure, and the second, describe the different CPU component functions.

So let's start with define the von Neumann architecture structure.

Computer architecture is a term used to describe the design of a computer system.

Modern computers used the von Neumann architecture designed by John von Neumann.

And you can see a picture of him here on the slide.

In the beginning, computers were nowhere near as efficient or small as they are now.

The instructions they ran were hardwired, physical switches that your data went through.

This meant changing one thing in your programme could take months to check.

von Neumann proposed a new way to store and run programmes on a computer.

His idea was to store common instructions in memory alongside the data, making computers much more versatile; and both were stored in binary.

This computer architecture has been widely adopted today.

You can see an example of the binary on the right of the zeros and ones.

Let's have a quick check.

Which of the following is true about the von Neumann architecture? Is it A: instructions are stored in decimal format while data is stored in binary, B: data is stored using a different numbering system than instructions, C: Both instructions and data are stored in binary, or D: instructions are stored as high level programming code, which is then translated into binary? Pause the video to consider your answer and then we'll check it.

Let's check your answer.

The answer was C.

Both instructions and data are stored in binary.

Well done if you got that correct.

The von Neumann architecture consists of: a processor, a memory unit that communicates directly with the processor, connections for input and output devices, secondary storage for saving and backing up data.

Let's have a quick check.

Which of the following are key features of the von Neumann computer architecture? Is it A: processor and main memory, B: input and output device connections, C: secondary storage, or D: operating system? There's more than one answer.

Pause the video, go back through the slides, consider your answer and then we'll check it.

Let's check your answer.

The answers was A, B, and C, processor and main memory, input and output device connections and secondary storage.

Well done if you got that correct.

The von Neumann computer architecture has the following characteristics: Data and instructions are stored as binary digits.

The instructions are fetched from memory one at a time in order and the processor decodes an instruction before it executes it.

In the von Neumann computer architecture, data moves between different component via buses.

A bus is a communication pathway along which data signals are transmitted around the CPU.

There are three types of buses used: the address bus, the data bus and the control bus.

The address bus is used to tell the memory which specific location it wants to access.

This could be to fetch an instruction or to read or write data.

It's like sending a specific postcode or house number.

The data bus is used to transfer the actual data or instructions between the CPU, memory and input/output devices.

It is like the actual delivery truck carrying the information.

The control bus carries control signals that coordinate the activities of all the different components.

These signals ensure that everything happens in the correct order and at the right time.

It is like the traffic signals and the police officers of the computer's communication system.

Let's have an activity and you'll need your worksheet for this.

The first activity is to complete the diagram by labelling the von Neumann architecture.

Pause the video, use your worksheet, go back through the slides and label your diagram and then we'll check your answer.

Let's check your answer.

You have the input and output controllers in the middle, followed by slightly to the right, the processor, and far right, the main memory.

The buses are the black lines in between.

You have at the top, the input devices, and underneath at the bottom, the output devices, and on the far left, the secondary storage.

Well done if you got that correct.

Let's look at another activity.

This time, describe the different buses used in the von Neumann architecture.

Pause the video, go back through the slides and describe the different buses and then we'll check your answer.

Let's check your answer.

The address bus is used to tell the memory which specific location it wants to access.

This could be to fetch an instruction or to read or write data.

The data bus is used to transfer the actual data or instructions between the CPU, memory and input/output devices.

The control bus carries control signals that coordinate the activities of all the different components.

These signals ensure that everything happens in the correct order and at the correct time.

Well done if you've got that correct.

Let's move on to the second part of today's lesson.

Describe the different CPU component functions.

CPU stands for central processing unit.

It is the core of a computer as it receives and executes instructions.

In order to follow the von Neumann computer architecture system, modern CPUs contains several key components that all play a key role.

Inside the CPU, there are a number of key components: the control unit, the arithmetic logic unit, buses, registers, and clock.

The control unit runs the show.

It understands the instructions and tells the other components what each instruction needs from them.

The control unit is organised, efficient, and collaborative.

It manages the instructions and controls the other components.

You can see it labelled here, right in the centre of the CPU diagram.

The arithmetic logic unit, referred to as the ALU, is the calculator of the CPU.

It handles mathematical and logical operations that are required as part of an instruction.

The ALU is logical, good with numbers and precise.

It manages calculations and logic.

You can see it labelled there on the left of the CPU diagram.

The CPU contains an internal clock that is used to regulate the number of cycles carried out per second and synchronise the other components.

It is punctual, reliable, and has good rhythm.

It manages the cycles per second.

You can see it on the right of the CPU diagram.

Let's have a quick check.

Which of the following describes the control unit? Is it A: it handles mathematical and logical operations that are required as part of an instruction? Is it B: it understands the instructions and tells the other components what each instruction needs from them? Is it C: It is used to regulate the number of cycles carried out per second and synchronise the other components? Or is it D: they are very small, very fast memory locations located inside the CPU? Pause the video, go back through the slides and consider your answer and then we'll check it.

Let's check your answer.

The answer was B.

It understands the instructions and tells the other components what each instruction needs from them.

Well done if you got that correct.

Which of the following describes the arithmetic logic unit? Is it A: It handles mathematical and logical operations that are required as part of an instruction? Is it B: It understands the instructions and tells the other components what each instruction needs from them? Is it C: It is used to regulate the number of cycles carried out per second and synchronise the other components? Or is it D: they are very small, very fast memory locations located inside the CPU? Pause the video, go back through the slides and consider your answer and then we'll check it.

Let's check your answer.

The answer was A.

It handles mathematical and logical operations that are required as part of an instruction.

Well done if you got that correct.

Registers are very small, very fast memory locations located inside the CPU and there are different types of registers.

The memory address register referred to as the MAR, the mar, the memory data register, referred to as MDR.

The current instruction register, referred to as CIR, and the programme counter, referred to as the PC and the accumulator, referred to as Acc.

The memory address register, the MAR, stores memory addresses used when searching for data in RAM.

The memory data register, MDR, stores the data when it's fetched from memory.

Let's have a quick check.

Which of the following describes the memory data register, the MDR? Is it A: holds the binary representation of the instruction to be executed, B: stores the data when fetch from memory, C: stores memory addresses used when searching for data in RAM, or D: counts up as each instruction is executed? Pause the video, go back through the slides and consider your answer and then we'll check it.

Let's check your answer.

The answer was B.

It stores the data when fetched from memory.

Well done if you got that correct.

The current instruction register, the CIR, holds the binary representation of the instruction to be executed.

The programme counter, the PC, counts up as each instruction is executed, keeping track of how many instructions are in a programme.

The accumulator, Acc, stores important data being used in calculations.

All registers are fast and reliable memory.

Let's look at an activity and you'll need your worksheet.

The first part of the activity is to label the CPU diagram with the different components.

Pause the video, use your worksheet, go back through the slides and label your diagram and then we'll check your answers.

Let's check your answers.

We have the clock in the top right, the ALU on the left, control unit in the middle and the registers at the bottom.

And the lines connecting are the different buses.

Well done if you got that correct.

Let's look at the next part of the activity and in this one you need to complete the table to describe the different CPU component functions.

You have the component on the left, the control unit, arithmetic logic unit, and the clock.

You need to add the description of what that is, the characteristics of it, and what does it control or manage? Pause the video, go back through the slides, complete your table on the worksheet and then we'll check your answers.

Let's check your answers.

The control unit.

The description is: It understands the instructions and tells the other components what each instruction needs from them.

Characteristics.

It is organised, efficient, and collaborative and it manages the instructions and controls the other components.

The arithmetic logic unit is the calculator of the CPU.

It handles mathematical and logical operations that are required as part of an instruction.

The characteristics are that it's logical, good with numbers and precise, and it manages calculations and logic.

The clock.

If the CPU contains an internal clock that is used to regulate the number of cycles carried out per second and synchronise the other components.

The characteristics are that it's punctual, reliable, and good rhythm.

And it controls the cycles per second.

Well done if you got those correct.

The third part of this activity is to complete the table to describe the different registers and their functions in the CPU.

You have a table, on the left you have the registers, the memory address register, memory data register, current instruction register, programme counter and accumulator.

You need to add the abbreviation and a description of its function.

Pause the video, go back through the slides, complete the table on your worksheet, and then we'll check your answers.

Let's check your answers.

The memory address register, the abbreviation is MAR and it stores memory addresses used when searching for data in RAM.

Memory data register, the abbreviation is MDR, stores the data when fetched from memory.

Current instruction register, abbreviation is CIR, holds the binary representation of the instruction to be executed.

The programme counter, the abbreviation is PC, this register counts up as each instruction is executed, keeping track of how many instructions are in a programme.

The accumulator, abbreviation Acc, stores important data being used in calculations.

Well done if you got those correct.

In summary, the von Neumann computer architecture is a design of a computer system.

It stores common instructions in memory alongside the data.

Inside the CPU, there are a number of key components, each with its own function, including the control unit, arithmetic logic unit, buses, registers, and clock.

A register is very small and fast memory location inside the CPU.

These include the memory address register, MAR, memory data register, MDR, current instruction register, CIR, programme counter, PC, and accumulator, Acc.

Well done for completing this lesson on the processor.