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MT-210 Computer Fundamentals
Tutorial 8 ( part 1 )
Group 17
Tutor : Kenny YUEN
http://learn.ouhk.edu.hk/~t441063
Chapter 5 (Set Book)Computer Architecture
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It refers to the design & construction of a computer system
Computer Architecture
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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 memory
Use space on hard disk, as an extension of RAM, to simulate RAM. 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 FactorsSystem 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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RegisterCache
CMOS, ROMRAM
Primary Storage
Secondary Storage
Hard to increase
Easy to increase
Performance
Cost (bit / $ )
Decreasing
Increasing
Storage Size
Punch card, Tape
Floppy,
Zip disk,
CD,
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 load process store
Instruction-2 load process store
Instruction-3 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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