2.1 Components of the CPU

1. 2.1 Components of the CPU • Central Processing Unit (CPU) consists of • Control Unit • Arithmetic and Logic Unit • Registers • The components are connected by internal buses.

2. 2.1 Components of the CPU

3. 2.1 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

4. 2.1 Components of the CPU • Register • high-speed storage locations • temporarily hold data and instructions during processing

5. (1) fetch Memory Unit CU ALU (3) execute (2) decode CPU 2.1 Components of the CPU • Machine Cycle • Fetch • Decode • Execute

6. 2.1 Components of the CPU • Fetching • obtaining a program instruction or data item from memory

7. 2.1 Components of the CPU • Decoding • translating instructions into commands the computer can execute

8. 2.1 Components of the CPU • Executing • carrying out the command

9. 2.1 Components of the CPU • Storing • writing the result to the main memory

10. 2.2 Performance and Instruction Sets of the CPU • Determining factors of CPU performance • clock rate • word size • size of the cache • integrated circuit technology

11. 2.2 Performance and Instruction Sets of the CPU • Clock rate • number of pulses per second generated by an oscillator that sets the tempo for the CPU • measured in MHz or GHz • determine the number of executed instructions per second • not always directly proportional to its performance level

12. 2.2 Performance and Instruction Sets of the CPU • Word size • number of bits the processor can interpret and execute at a given time • e.g. 64-bit processor manipulates 64 bits at a time • larger the word size, more data can be processed in the same amount of time

13. 2.2 Performance and Instruction Sets of the CPU • Cache • small amount of high-speed memory located inside or outside of the CPU • supply the processor with the most frequently requested data and instruction

14. 2.2 Performance and Instruction Sets of the CPU • Integrated circuit technology • smaller process dimension  smaller transistor gate lengths  faster switching speed of transistor

15. Longer instruction execution cycle Shorter instruction execution cycle Allow each instruction to do more Allow each instructionto do less 2.2 Performance and Instruction Sets of the CPU Simple instruction set Complex instruction set

16. 2.2 Performance and Instruction Sets of the CPU • Complex Instruction Set Computer (CISC) • computers designed with full set of computer instructions • CISC CPU executes complex instruction more quickly than RISC CPU • e.g. Intel Pentium microprocessors

17. 2.2 Performance and Instruction Sets of the CPU • Reduced Instruction Set Computer (RISC) • microprocessor designed to perform a smaller number of simplecomputer instructions • reduce instructions to those used more frequently • RISC CPU executes simple instruction more quickly than CISC CPU • e.g. PowerPC microprocessor

18. 2.2 Performance and Instruction Sets of the CPU • Advanced technology used in CPU • Pipelining • Superscalar • Parallel processing

19. 2.2 Performance and Instruction Sets of the CPU • Pipelining • CPU begins executing a second instruction before it completes the first instruction • faster processing • effective only if the CPU execute programs sequentially for most of the time

20. Fetch Decode Execute Fetch Decode Execute Instruction 2 Instruction 1 2.2 Performance and Instruction Sets of the CPU Instruction flow without pipelining

21. Fetch Decode Execute Instruction 1 Instruction 2 Instruction 3 2.2 Performance and Instruction Sets of the CPU Instruction flow with pipelining

22. 2.2 Performance and Instruction Sets of the CPU • Superscalar • possible for executing more than one instruction at a time during a single clock cycle • Parallel Processing • allocation of program execution to many execution units to execute more than one instruction in one cycle

23. 2.3 Layouts of the Main Board • All the peripherals plug into the main board via various types of connector • Advantages of ATX main board • Integrated I/O connectors • Reduced overlap between board and drivers • Reduced processor interference with add-on cards • User-friendly power connector • Better cooling conditions

24. I/O connectors Northbridge PCI slots CPU socket Memory BIOS Floppy drive Battery Power supply connector Southbridge AGP slot IDE connectors 2.3 Layouts of the Main Board

25. 2.4 North Bridge / South Bridge • North Bridge • communicate with CPU • control interaction with memory, PCI bus, Level 2 cache and AGP • communicate with the processor using Frontside Bus (FSB)

26. 2.4 North Bridge / South Bridge • South Bridge • manage the basic forms of input/output (USB, serial, audio, IDE, ISA)

27. PCI expansion slots 2.5 I/O Expansion Slots of the Main Boards • PCI (Peripheral Component Interconnect) • interconnection system between a CPU and attached devices • separate bus isolated from the CPU • use all active paths to transmit both address and data signals

28. AGP slot 2.5 I/O Expansion Slots of the Main Boards • AGP (Accelerated Graphics Port) • enable 3-D graphics to display quickly and smoothly on ordinary personal computers • useful in gaming, 3-D video, scientific graphic programs • intended exclusively for visual display devices

29. 2.5 I/O Expansion Slots of the Main Boards • AGP (Accelerated Graphics Port) • offer high-speed data transfer to and from RAM • optimize the use of memory • minimize the amount necessary for high-performance graphics • AGP data transfer rate is much greater than that of PCI video cards.

30. 2.5 I/O Expansion Slots of the Main Boards • PCI and AGP

31. END