an overview of the processors role in a computer system

1. THE
COMPUTER
SYSTEM
L E S S O N 1 : T H E B A S I C C O M P U T E R
A R C H I T E C T U R E ( PA R T 1 – T H E P R O C E S S O R )

2. LEARNING
INTENTIONS
Describe the purpose of the
basic computer architecture
components and how they are
linked together including:
• Processor
• Memory
• Buses
• Interfaces

3. WHAT IS A
COMPUTER?

5. COMPUTER ARCHITECTURE
• The structure of a computer system
• What a computer system is made up of
• The different parts of a computer system
and how they are connected together

6. HARDWARE • Physical parts of a
computer
• Parts that you can
see and touch
• Even physical parts
inside the system
unit

7. MAIN COMPONENTS
CPU
Main
Memory
Secondary

8. MAIN COMPONENTS
Processor
Main Memory
Backing Storage
input output

9. THE
PROCESSOR

10. WHAT IS THE PROCESSOR?
• Central Processing Unit (CPU)
• Brain of the computer
• Carries out all processing: fetching, decoding and
executing of instructions.
• Performs mathematical calculations & logical
decisions

11. WHAT IS THE PROCESSOR?
• Runs/executes one instruction at a
time
• Microprocessors are used in
personal computers
• Two or more CPU’s on the same
chip has made computers faster.

12. • Number of instructions executed per second.
• It is a frequency
• Measured in Hertz (Hz), nowadays in GigaHertz
(GHz)
•The faster the CPU the faster the computer, since
more instructions are worked out per second
PROCESSOR SPEED

13. PROCESSOR SPEED
Example – 2.5GHz CPU
frequency = 1 / time
2.5GHz = 1 / time
time = 1 / 2.5GHz
time = 1 / 2,500,000,000
time = 0.0000000004s
time = 4ns (nano seconds)

14. •Control Unit (CU)
•Arithmetic Logic Unit
(ALU)
•Memory Unit (MU)
COMPONENTS OF A CPU

15. • Controls the flow of
data inside the CPU
• Controls input and
output of data
• Controls and
monitors hardware
COMPONENTS OF A CPU – Control Unit

16. • Controls sequence of
instructions to be executed
• Control flow of data among all
parts of a computer
• Interpret instructions
• Regulate timing of the processor
• Send a control signal to and
receive a control signal from
peripheral devices
COMPONENTS OF A CPU – Control Unit

17. • Two sections:
Arithmetic and Logic
• Arithmetic part:
carries out all
mathematical operations
like + - * /
• E.g. z = x + y
COMPONENTS OF A CPU – Arithmetic Logic Unit

18. • Logic part:
AND, OR, NOT, >, <, >=,
<=, =, ≠
• Comparison of values
• E.g. if x > y
COMPONENTS OF A CPU – Arithmetic Logic Unit

19. • Registers
• Temporary Storage
• Very small, fixed size
• Store one value or
instruction at a time
COMPONENTS OF A CPU – MEMORY UNIT

20. • Fast Speed since they are already inside the CPU so
no need for travelling
• One register is divided into spaces each with a 0 or a
1
COMPONENTS OF A CPU – MEMORY UNIT

21. • General Purpose Registers:
Store any value/instruction
• Special Purpose Registers:
Store one type of
value/instruction
COMPONENTS OF A CPU – MEMORY UNIT

22. Registers in the Control Unit:
• Program Counter (PC)
• Instruction Register (IR)
AddressBus
DataBus
Control Unit
Program Counter (PC)
InstructionRegister (IR)
COMPONENTS OF A CPU – MEMORY UNIT

23. • Program Counter (PC) stores the address of the
next instruction to be executed.
• Updated every time an instruction is run.
AddressBus
DataBus
Control Unit
Program Counter (PC)
InstructionRegister (IR)
COMPONENTS OF A CPU – MEMORY UNIT

24. • Instruction Register (IR)
• Contains a copy of the instruction being executed at
that time
AddressBus
DataBus
Control Unit
Program Counter (PC)
InstructionRegister (IR)
COMPONENTS OF A CPU – MEMORY UNIT

25. Registers in the ALU:
• Accumulator stores results
• Shift Register carries out
multiplications and
divisions
COMPONENTS OF A CPU – MEMORY UNIT