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2.12.1 Components of the CPUComponents of the CPUCentral Processing Unit (CPU) consists of
Control Unit
Arithmetic and Logic Unit
Registers
The components are connected by internal buses.
2.12.1 Components of the CPUComponents 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
2.12.1 Components of the CPUComponents of the CPU
Registerhigh-speed storage locations
temporarily hold data and instructions during processing
2.12.1 Components of the CPUComponents of the CPU
CPU
Machine CycleFetchDecodeExecute
2.12.1 Components of the CPUComponents of the CPU
CUALU
Memory Unit
(1) fetch
(2) decode(3) execute
Fetchingobtaining a program instruction or data item from memory
2.12.1 Components of the CPUComponents of the CPU
Decodingtranslating instructions into commands the computer can execute
2.12.1 Components of the CPUComponents of the CPU
Executingcarrying out the command
2.12.1 Components of the CPUComponents of the CPU
Storingwriting the result to the main memory
2.12.1 Components of the CPUComponents of the CPU
Determining factors of CPU performanceclock rate
word size
size of the cache
integrated circuit technology
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Clock ratenumber 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
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Word sizenumber 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
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Cachesmall amount of high-speed memory located inside or outside of the CPU
supply the processor with the most frequently requested data and instruction
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Integrated circuit technologysmaller process dimension smaller transistor gate lengths faster switching speed of transistor
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Complex instruction set Simple instruction set
Longer instruction execution cycle
Allow each instruction to do more
Shorter instruction execution cycle
Allow each instructionto do less
Complex Instruction Set Computer (CISC)computers designed with full set of computer instructionsCISC CPU executes complex instruction more quickly than RISC CPUe.g. Intel Pentium microprocessors
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Reduced Instruction Set Computer (RISC)microprocessor designed to perform a smaller number of simple computer instructionsreduce instructions to those used more frequentlyRISC CPU executes simple instruction more quickly than CISC CPUe.g. PowerPC microprocessor
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Advanced technology used in CPUPipeliningSuperscalarParallel processing
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
PipeliningCPU begins executing a second instruction before it completes the first instructionfaster processingeffective only if the CPU execute programs sequentially for most of the time
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Fetch Decode Execute Fetch Decode Execute
Instruction 1 Instruction 2
Instruction flow without pipelining
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
Fetch Decode Execute
Instruction flow with pipelining
Instruction 1
Instruction 2
Instruction 3
Superscalarpossible for executing more than one instruction at a time during a single clock cycle
Parallel Processingallocation of program execution to many execution units to execute more than one instruction in one cycle
2.22.2 Performance and Instruction Sets Performance and Instruction Sets of the CPUof the CPU
All the peripherals plug into the main board via various types of connector
Advantages of ATX main boardIntegrated I/O connectors
Reduced overlap between board and drivers
Reduced processor interference with add-on cards
User-friendly power connector
Better cooling conditions
2.32.3 Layouts of the Main BoardLayouts of the Main Board
2.32.3 Layouts of the Main BoardLayouts 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 Bridgecommunicate with CPU
control interaction with memory, PCI bus, Level 2 cache and AGP
communicate with the processor using Frontside Bus (FSB)
2.42.4 North Bridge / South BridgeNorth Bridge / South Bridge
South Bridgemanage the basic forms of input/output (USB, serial, audio, IDE, ISA)
2.42.4 North Bridge / South BridgeNorth 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
2.52.5 I/O Expansion Slots of the Main I/O Expansion Slots of the Main BoardsBoards
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
2.52.5 I/O Expansion Slots of the Main I/O Expansion Slots of the Main BoardsBoards
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.
2.52.5 I/O Expansion Slots of the Main I/O Expansion Slots of the Main BoardsBoards
PCI and AGP
2.52.5 I/O Expansion Slots of the Main I/O Expansion Slots of the Main BoardsBoards
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