information process cycle

1. CPU and Its Parts

2. Components of the CPU
Central Processing Unit (CPU) consists of
• Control Unit
• Arithmetic and Logic Unit
• Registers
• The components are connected by internal
buses.

3. Components of CPU

4. Components of the CPU
Control Unit (CU)
• “nerve centre” of CPU
• send control signals to other components
• sense their states to coordinate their operations
• Arithmetic and Logic Unit (ALU)
• perform arithmetical, comparison and logical
operation
• work closely with the accumulation

5. Components of the CPU
Register
• high-speed storage locations
• temporarily hold data and instructions during
processing
Fetched instruction is placed in the instruction register
• Categories
– Processor-memory
• Transfer data between processor and memory
– Processor-I/O
• Data transferred to or from a peripheral device
– Data processing
• Arithmetic or logic operation on data
– Control
• Alter sequence of execution

6. Instruction Execution Cycle
• The time period during which one instruction
is fetched from memory and execute when
computer given an instruction in machine
language.
• Each instruction is further divided into
sequence of phases.
• After the execution of program counter
is incremented to point to the next instruction.

7. • Processor reads instruction from memory
time .
• Decodes the instruction.
• Execute the instruction
Process

8. Machine Cycle
• Fetch
• Decode
• Execute
Instruction Cycle

9. Fetch Cycle
The Program Counter (PC) contains the address
of the next instruction to be fetched.
The address contained in the PC is copied to the
Memory Address Register (MAR).

10. • The instruction is copied from the memory
location contained in the MAR and placed in the
Memory Buffer Register (MBR).
• The entire instruction is copied from the MBR
and placed in the Current Instruction Register
(CIR)

11. • The address part of the instruction is placed
in the MAR
• The instruction is decoded and executed.
• The processor checks for interrupts and
either branches to the relevant interrupt
service routine or starts the cycle again.

12. Start
Halt
Fetch
Instruction
Decode
Instruction
Execute
Instruction

13. Fetching
• obtaining a program instruction or data item from
memory
Instruction Cycle

14. Instruction Cycle
Decoding
• translating instructions into commands the
computer can execute

15. Executing
carrying out the command
Instruction Cycle

16. • Storing
writing the result to the main memory
Instruction Cycle