Transcript Unit-5 - GEOCITIES.ws

MT-210 Computer Fundamentals
Chapter 5 (Set Book)
Computer Architecture
Tutorial 8 ( part 1 )
Group 17
Tutor : Kenny YUEN
http://learn.ouhk.edu.hk/~t441063
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Computer Architecture
 It refers to the design & construction of a computer system
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Motherboard (底板) or main board
 Provide sockets for
chips (IC), slots for
small circuit board,
and circuitry that
connecting these
components
 Provide expansion
slots for connection
with peripheral
devices
 such as EISA,
PCI & APG
slot
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 Integrated Circuit (IC)
 A thin slice of silicon crystal packed with microscopic
circuits elements such as :
 Wires, Transistors, Capacitors, and resistors
 Chip Packages, including
 DIP (dual in-line pin),
 DIMM (dual in-line memory module)
 PGA (pin-grid array)
 SEC (single edge contact)
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Data Representation
 An Analog device operates on continuously varying data
 A Digital device works with discrete number,
 digital computer represent numeric data using Binary Number system
 Which has only 2 digits : [ 0 ] and [ 1 ]
 "Character data" composed of letter, symbol, & numeral that will not
be used in arithmetic operations
 digital computers represent character data using codes and "Code Set".
 ASCII := American Standard Code for Information Interchange
 EBCDIC := Extended Binary-Coded Decimal Interchange Code
 Most micro-computers use ASCII code to represent character data
 Some mini, mainframe computers use EBCDIC code to represent
character data
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Code Sets
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Data Transport
 [ Data bus ] is an electronic pathway or circuit that links the chips on the
motherboard for data to travel
 The bus contains data line and address line
 [data line ]
: carry the signals that represent data
 [address line ] : carry the signals that specify where the computer
can find the data that it is supposed to process
Memory
 There are 2 major categories : Primary & Secondary
 There are 4 major types of memory :
 RAM : Random Access Memory
 Virtual Memory : by the use of hard disk
 CMOS : Complementary Metal Oxide Semiconductor
 ROM : Read Only Memory
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RAM
 Temporarily holds {data, instructions } before/after it is processed until
the computer is turn off.
 Require power to hold. No power, then no data.
 A reusable computing resource as the contents can be changed
Virtual
 Use space on hard disk, as an extension of RAM, to simulate RAM.
memory  Works slower than RAM because
 RAM is electronic device
 Hard disk is mechanical device
 Like RAM : no power, then data in virtual memory become in-accessible
ROM
 One or more chips containing instructions that help a computer prepare
for processing tasks
 Instructions in ROM are permanent
 The only ways to remove instructions is to remove that chips
 Holds Basic I/O system (BIOS) for PC bootstrap & tells the computer
how to access disk drives and other peripheral devices
CMOS
 More permanent then RAM but less permanent then ROM
 Stores hardware configuration, which can be changed
 Memory is powered by battery
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Central Processing Unit (CPU)
 The circuitry in a computer that execute instruction to process date
 It takes instruction/data from RAM, process instructions then places the
results back into RAM
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There are 2 main parts :
1/. Arithmetic Logic Unit (ALU),
 performs arithmetic operations such as addition & subtraction
 performs Logical operations such as comparing 2 numbers to check
if they are the same
 Use registers to hold data that is being processed
 The result of the ALU will be kept in accumulator,
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2/. Control Unit (CU),
 direct & control processing
 Use instruction pointer to keep track of instruction sequence
 Retrieve each instruction in sequence from RAM and place it in
instruction register
 Interpret the instruction &
 may send signal to
data bus to :
 fetch data from RAM
 to the ALU to perform
a process
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Instructions
 tells the computer to perform arithmetic, logical, or control operation
 It has 2 parts
 [op code ] = "operation code", a command word for an operation
 Such as add, compare, or jump
 [operands ] specify the data or address of the data for the operation
 [ Instruction cycle] as, shown in margin,
refers to the process that a computer executes
a single instruction
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Processing Instructions
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Performance Factors
System Clock
 generates pulses to establish the timing for all system operations,
 sets speed/frequency for data transport & instruction execution
 Thus, limits no of instructions to be completed in a fixed time slot
Word size
 The no. of bits a CPU can manipulate at one time
 Based on size of registers in the CPU & no. of data line in the bus
Cache
 "RAM cache" or "cache memory", high speed memory that give the
CPU more rapid access to data
 when an instruction calls for data, the CPU 1st checks if it is in cache.
 If yes, it takes it from cache. Otherwise, it fetch it from RAM which
takes longer
 Generally, more cache means faster processing
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Decreasing
 Primary Storage
 Secondary Storage
 Performance
 Hard to increase
 Cost (bit / $ )
Register
Cache
 Easy to increase
Increasing
CMOS, ROM
RAM
 Storage
Size
Floppy,
Zip disk,
CD,
Punch card,
Tape
DVD
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Instruction Set Complexity
CISC (Complex Instruction Set Computer)
 Complex instructions are provided in this kind of machine, however
 20% of the instructions of a CICS machine do about 80% of the work
RISC (Reduced Instruction Set Computer)
 Has limited set of instructions that it can perform very quickly
 In theory a RISC machine is faster than CISC machine for most tasks
 Scientists believe that a balance or hybrid of CISC & RISC technologies
produces the most efficient and flexible computer
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Pipelining
 To speed up the processing
 A processor can begin executing part of the next instruction(s) before
the current instruction-1 completed, as shown below
Instruction-1
Instruction-2
Instruction-3
load
process
store
load
process
store
load
process
store
Time
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Parallel Processing
 these are Parallel Computers
 Increase the amount of processing that a computer can accomplish in
a specific amount of time
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Input & Output (IO)
 Refers to collecting data for the microprocessor to manipulate, and
transporting results to display, print and storage devices
 [ Expansion Bus ] is a segment of the data bus that transports data between
RAM and peripheral devices
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Expansion Slots & Cards
 Expansion Slot is a long, narrow socket on the motherboard, where
you can plug your expansion cards
 expansion card / controller card is a small circuit board that
provides a computer with the ability to control a storage, input, or output
devices
 Examples
 Sound card
 Modem card
 LAN card
 Capture card
 AGP graphic card
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ISA
 Industry Standard Architecture
 An obsolete technology, used for some modem and other relatively slow
devices
PCI
 Peripheral Component Interconnect
 Offers faster transfer speeds and a 64-bit data bus
 Houses graphics card, sound card, video capture card, modem or
network interface card (LAN card)
AGP




Accelerated Graphics Port
Primarily used for graphics cards,
Faster than a PCI slot
Provides a high speed data pathway for 3D graphics
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Expansion port & cable
 Expansion Port is any
connector that passes data in &
out of a computer or peripheral
device
 Ports are sometimes called
"jacks" or "connector"
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