1. Starter: Stored Program Concept (von Neumann Architecture)
Video
There is one main memory store
Both data and instructions reside in same memory store
Data and instructions are fetched (copied) from memory over the same set of buses

2. Role of the Processor in the Fetch-Decode-Execute Cycle
4.2.2
Teacher to explain

3. Starter: Stored Program Concept (von Neumann Architecture)
John von Neumann
Hungarian mathematician, physicist inventor
Born 1903
Died 1957
Optional Video

4. Learning Objectives
4.1.1 understand the input-process-output model understand the function of the hardware components of a computer system (CPU, main memory, secondary storage, input and output devices) and how they work together understand the function of different types of main memory (RAM, ROM, cache) understand the concept of a stored program and the role of components of the CPU (control unit (CU), arithmetic/logic unit (ALU), registers, clock, address bus, data bus, control bus) in the fetch-decode-execute cycle (the Von Neumann model)

5. How data is retrieved and stored
Step two.
The CPU tries to find the info in the cache of the CPU
Step three.
If it cant be found it tries to retrieve the data from the RAM
How data is retrieved and stored
Step Four.
If it cant be found it tries to retrieve the data from the Hard Drive
Step Five.
Once the data is found the data is sent back to the CPU for execution
Step one.
You search for a file. This message gets sent to the CPU

6. The difference in speed
You want to get something delivered to your house from Amazon. There are 3 ways to get this done.
Via lorry from the depot in Scotland which takes several days
You could use Amazon Prime and get it next day delivery, this is delivered via a car
You could use Amazon Prime Air and it will be with you within an hour, but this is delivered via drone and can only be small items.
Which one do you think is the Hard drive, RAM and CPU?

7. Meet: BORIS – A Simple Microprocessor
Beginner’s Optimised Reduced Instruction Set (you don’t need to remember that)
BORIS is the pink component in the image
Can you connect what you know about the von Neumann architecture to the image on the right?
What is added?
Clock
Control Bus

8. BORIS: Executing a Program
Computer program
Instructions to execute and data to work on
Main memory
Program instructions
Data needed by the program
Microprocessor
The hardware which decodes the instruction and executes the instruction, using the data
Clock
How often each instruction can be processed (metronome)
Control bus explained in a few minutes.

9. Your Turn: Executing a Program
5 Min
Your Turn: Executing a Program
Using ALL of these words and their definitions, write down how a program is executed
Computer program
Main memory
Microprocessor
Clock
Remember: von Neumann Architecture
Use the words: fetch, decode, and execute
Control bus explained in a few minutes.

10. Answer: Executing a Program
Red words are vocabulary; green words show your understanding.
Answer: Executing a Program
A computer program (instructions and data) is loaded into a computer’s main memory (random access memory).
On each clock tick, an instruction is fetched (copied) from main memory into the microprocessor.
The microprocessor decodes (interprets) and executes the instruction.
This is repeated for each clock tick.
Really Important
Control bus explained in a few minutes.

11. BORIS and External Busses
Address bus
Holds the address (location) in memory of the next instruction to be executed
Data bus
Holds the contents of a memory location (if reading)
Holds real data, if writing
Control bus
Coordinates different parts of the microprocessor
Like a conductor

12. Example: Read Read an instruction from memory Clock ticks
Red words are vocabulary; green words show your understanding.
Example: Read
Read an instruction from memory
Clock ticks
Address of next instruction to execute (0109) is put on address bus
Control bus indicates ‘read’
Contents of memory location held on address bus ( ) is put on data bus
Microprocessor receives ( ) off data bus
Address
Contents …
0109
010A
010B
010C
Where did go? We’ll look inside BORIS in a few minutes.

13. Example: Write Write data to memory Clock ticks
Red words are vocabulary; green words show your understanding.
Example: Write
Write data to memory
Clock ticks
Address of memory location to store/write data (010C) is put on address bus
Data ( ) is put on the data bus
Control bus indicates ‘write’
Contents of data bus is written to the memory location held on the address bus
Address
Contents …
0109
010A
010B
010C

14. Your Turn: Role of Busses
5 Min
Your Turn: Role of Busses
Using ALL of these words, write down how the different busses are used in executing instructions
Address bus
Data bus
Control bus
Remember: Read and Write

15. Answer: Role of Busses
The address bus holds the address of the next memory location to read from or write to.
The control bus issues either a ‘read’ or a ‘write’ signal to cause an operation to take place.
On a write operation, the data bus holds the data to write to the memory location whose address is on the address bus.
On a read operation, the data bus holds a copy of the contents of the memory location whose address is on the address bus.

16. Other Devices

17. BORIS: Inside a Microprocessor (1)
The microprocessor is everything inside the dotted line.
What can you recognise from previous images?
Data bus?
Address bus?
Control bus?
Clock?

18. BORIS: Inside a Microprocessor (2)
Cache
Very fast specialised memory
Acts as a storage location for frequently accessed instructions/data
If a requested instruction/data is found in cache, it saves an Input/Output operation to main memory
That speeds up processing time
Arithmetic Logic Unit (ALU)
Performs arithmetic and logic operations
+, -, AND, OR, NOT
Internal registers
Specialised storage (memory) locations which hold a single instruction, data, or address
There are several of them, each with different roles
Control unit
Issues signals to coordinate rest of components
Issues signals to give ALU the type of instruction to execute

19. BORIS: Execute ( )
The number 11 is copied from main memory or cache into Register 1
The number 22 is copied from main memory or cache into Register 2
The control unit sends a signal to the ALU to add Register 1 to Register 2 and put the result into Register 3
The arithmetic logic unit adds the contents of Register 1 to Register 2 and puts the result in Register 3

20. Plenary: Vocabulary Arithmetic Logic Unit Registers Cache Control Unit
Address Bus
Data Bus
Control Bus C F B G A D E
Fast memory which holds frequently accessed data
Holds the contents of a memory location
Fast memory which holds a single piece of data to work on
Holds signals being transmitted to components
Performs +, -, AND, OR, NOT
In charge of coordinating microprocessor components
Holds the location of data or instructions in memory

21. Homework How a CPU Works Inside your computer
Inside your computer
Complete the worksheet for this lesson
Due in 2 lessons time

22. Resources

23. Resources
Processor
Addresses
Main Memory
Data and Instructions