3. Controls all the operations in the CPU
Transfers data to registers
Directs data to ALU for calculation
Ensures correct paths for data transfer
Synchronisation with the system clock
Click on image to
go to the Fetch-
Execute Cycle
4. Performs calculations
Tests logic functions
Determines relative relationships between values
Click on image to
go to the Fetch-
Execute Cycle
5. Storage register
Stores the next instruction to be executed
Accumulator
Stores the latest results from a calculation
Address register
Stores memory address locations
Instruction register
Stores instructions to be processed
Click on image to
go to the Fetch-
Execute Cycle
6. The system clock is an accurate, very fast
electronic timer.
The faster the system clock the more
instructions per second are executed.
7. Buses are pathways – separate wires / metallic
strips which transport signals (data).
http://www.webopedia.com/TERM/b/bus.html
8. Fetch:
•The instruction is fetched from memory.
•Instructions are stored in registers.
Decode
•the opcode is decoded by the CU so the instruction can be
executed.
Execute
•The instruction is executed, usually using the ALU.
Store
•The result of the instruction is stored.
Note: this is a simplified explanation (what is required knowledge for the Preliminary course – see link for further
detail).
http://en.wikipedia.org/wiki/Instruction_cycle
9. Decode:
• The typical instruction is divided into two parts: the Opcode
and the Operand
• The opcode is the instruction.
• The operand is the data on which the instruction needs to be
performed.
In the simplified example below:
Add 10
Add would be the instruction (opcode).
•
10 would be the data (operand).
•
10. More input / output devices
Increased processing speed
Larger memory (both primary and secondary)
which is better for working with sound and
graphics
