Chapter 2 The CPU and the Main Board  2.1 Components of the CPU 2.1 Components of the CPU 2.1 Components of the CPU  2.2Performance and Instruction Sets of the CPU 2.2Performance and Instruction Sets of the CPU 2.2Performance and Instruction Sets of the CPU  2.3Layouts of the Main Board 2.3Layouts of the Main Board 2.3Layouts of the Main Board  2.4North Bridge/South Bridge 2.4North Bridge/South Bridge 2.4North Bridge/South Bridge  2.5I/O Expansion Slots of the Main Board 2.5I/O Expansion Slots of the Main Board 2.5I/O Expansion Slots of the Main Board

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

2.1Components 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 2.1Components of the CPU

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

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

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

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

Executing carrying out the command 2.1Components of the CPU

Storing writing the result to the main memory 2.1Components of the CPU

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

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

Complex instruction set Simple instruction set Longer instruction execution cycle Allow each instruction to do more Shorter instruction execution cycle Allow each instruction to do less

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 2.2Performance and Instruction Sets of the CPU

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

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

FetchDecodeExecuteFetchDecodeExecute Instruction 1Instruction 2 Instruction flow without pipelining

2.2Performance and Instruction Sets of the CPU FetchDecodeExecute Instruction flow with pipelining Instruction 1 Instruction 2 Instruction 3

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 2.2Performance and Instruction Sets of the CPU

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 2.3Layouts of the Main Board

PCI slots BIOS Battery Floppy drive IDE connectors I/O connectors Memory Power supply connector Southbridge CPU socket Northbridge AGP slot

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

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

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 2.5I/O Expansion Slots of the Main Boards PCI expansion slots

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 2.5I/O Expansion Slots of the Main Boards AGP slot

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. 2.5I/O Expansion Slots of the Main Boards

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

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