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Computer Organization and Architecture
IntroductionChapters 1-2
Architecture & Organization 1
zArchitecture is those attributes visible to the programmeryInstruction set, number of bits used for data
representation, I/O mechanisms, addressing techniques.ye.g. Is there a multiply instruction?
zOrganization is how features are implemented, typically hidden from the programmeryControl signals, interfaces, memory technology.ye.g. Is there a hardware multiply unit or is it done by
repeated addition?
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Architecture & Organization 2
z All Intel x86 family share the same basic architecturez The IBM System/370 family share the same basic
architecture
z This gives code compatibilityyAt least backwardsyBut… increases complexity of each new generation. May be
more efficient to start over with a new technology, e.g. RISC vs. CISC
z Organization differs between different versions
Structure & Function
zComputers are complex; easier to understand if broken up into hierarchical components. At each level the designer should consideryStructure : the way in which components relate to
each otheryFunction : the operation of individual components
as part of the structure
zLet’s look at the computer top-down starting with function.
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Function
zAll computer functions are:yData processingyData storageyData movementyControl
Functional view
zFunctional view of a computer
DataMovementApparatus
ControlMechanism
DataStorageFacility
DataProcessingFacility
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Operations (1)
zData movementye.g. keyboard to screen
DataMovementApparatus
ControlMechanism
DataStorageFacility
DataProcessingFacility
Operations (2)
zStorage ye.g. Internet download to disk
DataMovementApparatus
ControlMechanism
DataStorageFacility
DataProcessingFacility
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Operation (3)
zProcessing from/to storage ye.g. updating bank statement
DataMovementApparatus
ControlMechanism
DataStorageFacility
DataProcessingFacility
Operation (4)
zProcessing from storage to I/Oye.g. printing a bank statement
DataMovementApparatus
ControlMechanism
DataStorageFacility
DataProcessingFacility
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Structure
zMajor Components of a ComputeryCentral Processing Unit (CPU) – Controls the
operation of the computer and performs data processingyMain Memory – Stores datayInput Output (I/O) – Moves data between the
computer and the external environmentySystem Interconnect – Some mechanism that
provides for communications between the system components, typically a bus (set of wires)
Structure - Top Level
Computer
Main Memory
InputOutput
SystemsInterconnection
Peripherals
Communicationlines
CentralProcessing Unit
Computer
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Structure - CPU
zMajor components of the CPUyControl Unit (CU) – Controls the operation of the CPUyArithmetic and Logic Unit (ALU) – Performs data
processing functions, e.g. arithmetic operationsyRegisters – Fast storage internal to the CPU, but
contents can be copied to/from main memoryyCPU Interconnect – Some mechanism that provides
for communication among the control unit, ALU, and registers
Structure - The CPU
Computer Arithmeticand Login Unit
ControlUnit
Internal CPUInterconnection
Registers
CPU
I/O
Memory
SystemBus
CPU
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Structure – Inside the CPU
zThe implementation of registers and the ALU we will leave primarily to EE 241zWe will say a bit about the architecture of the
control unit, there are many possible approaches. yA common approach is the microprogrammed control
unit, where the control unit is in essence itself a miniature computer, where a CPU instruction is implemented via one or more “micro instructions”⌧Sequencing Logic – Controlling the order of events⌧Microprogram Control Unit – Internal controls
⌧Microprogram Registers, Memory
Structure – A MicroprogrammedControl Unit
CPU
ControlMemory
Control Unit Registers and Decoders
SequencingLogin
ControlUnit
ALU
Registers
InternalBus
Control Unit
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Outline of the Stallings Text (1)
zComputer Evolution and PerformancezComputer Interconnection StructureszInternal MemoryzExternal MemoryzInput/OutputzOperating Systems SupportzComputer ArithmeticzInstruction Sets
Outline of the Stallings Text (2)
zCPU Structure and FunctionzReduced Instruction Set ComputerszSuperscalar ProcessorszControl Unit OperationzMicroprogrammed ControlzMultiprocessors and Vector ProcessingzDigital Logic (Appendix)
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Computer Evolution and Performance
Better, Faster, Cheaper?
History: ENIAC background
zElectronic Numerical Integrator And ComputerzEckert and MauchlyzUniversity of PennsylvaniazTrajectory tables for weapons, BRLzStarted 1943zFinished 1946yToo late for war effort
zUsed until 1955
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ENIAC - details
zDecimal (not binary)z20 accumulators of 10 digits (ring of 10 tubes)zProgrammed manually by switchesz18,000 vacuum tubesz30 tonsz15,000 square feetz140 kW power consumption (about $10/hr today)z5,000 additions per second
Vacuum Tubes
Grid regulates flow from of electrons from the cathode
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von Neumann/Turing
zENIAC : Very tedious to manually wire programszvon Neumann architecture:yStored Program conceptyMain memory storing programs and datayALU operating on binary datayControl unit interpreting instructions from memory and
executingyInput and output equipment operated by control unityPrinceton Institute for Advanced Studies ⌧IAS
yCompleted 1952
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Structure of von Neumann machine
MainMemory
Arithmetic and Logic Unit
Program Control Unit
InputOutputEquipment
IAS - detailsz 1000 x 40 bit wordsyBinary numbery2 x 20 bit instructions
z Set of registers (storage in CPU)yMemory Buffer RegisteryMemory Address RegisteryInstruction RegisteryInstruction Buffer RegisteryProgram CounteryAccumulatoryMultiplier Quotient
0 1 39
Sign bit
Number Word
Instruction Word
0 8 20 28 39
LeftOpCode Address
RightOpCode Address
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Structure of IAS - detail
MainMemory
Arithmetic and Logic Unit
Program Control Unit
InputOutputEquipment
MBR
Arithmetic & Logic Circuits
MQAccumulator
MAR
ControlCircuits
IBR
IR
PC
Address
Instructions& Data
Central Processing Unit
IAS Instruction Cycle
z The IAS repetitively performs the instruction cycle:yFetch⌧Opcode of the next instruction is loaded into the IR⌧Address portion is loaded into the MAR⌧Instruction either taken from the IBR or obtained from memory by
loading the PC into the MAR, memory to the MBR, then the MBR to the IBR and the IR
• To simplify electronics, only one data path from MBR to IR
yExecute⌧Circuitry interprets the opcode and executes the instruction⌧Moving data, performing an operation in the ALU, etc.
z IAS had 21 instructionsyData transfer, Unconditional branch, conditional branch,
arithmetic, address modification
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Commercial Computers
z1947 - Eckert-Mauchly Computer CorporationzUNIVAC I (Universal Automatic Computer)zUS Bureau of Census 1950 calculationszBecame part of Sperry-Rand CorporationzLate 1950s - UNIVAC IIyFasteryMore memoryyUpward compatible with older machines
IBM
zPunched-card processing equipmentz1953 - the 701yIBM’s first stored program computeryScientific calculations
z1955 - the 702yBusiness applications
zLead to 700/7000 series
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Transistors
zReplaced vacuum tubeszSmallerzCheaperzLess heat dissipationzSolid State devicezMade from Silicon (Sand)zInvented 1947 at Bell LabszShockley, Brittain, Bardeen
Transistor Based Computers
zSecond generation of machineszNCR & RCA produced small transistor machineszIBM 7000zDEC - 1957yProduced PDP-1
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IBM 7094
zLast member of the 7000 seriesy50 times faster than the 701⌧1.4 uS vs. 30 uS cycle
y32K memory vs. 2KyMain memory: Core memory vs. TubesyCPU memory: transistors vs. Tubesy185 vs. 24 opcodesyInstruction fetch overlap, reduced another trip to
memory (exception are branches)yData channels, independent I/O module for devices
3rd Generation: Integrated Circuits
zSelf-contained transistor is a discrete componentyBig, manufactured separately, expensive, hot when
you have thousands of them
zIntegrated CircuitsyTransistors “etched” into a substrate, bundled
together instead of discrete componentsyAllowed thousands of transistors to be packaged
together efficiently
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Microelectronics
zLiterally - “small electronics”zA computer is made up of gates, memory cells
and interconnectionszThese can be manufactured on a
semiconductor, e.g. silicon waferyThin wafer divided into chipsyEach chip consists of many gates/memory cellsyChip packaged together with pins, assembled on a
printed circuit board
Generations of Computer
z Vacuum tube - 1946-1957z Transistor - 1958-1964z Small scale integration - 1965 onyUp to 100 devices on a chip
z Medium scale integration - to 1971y100-3,000 devices on a chip
z Large scale integration - 1971-1977y3,000 - 100,000 devices on a chip
z Very large scale integration - 1978 to datey100,000 - 100,000,000 devices on a chipyPentium IV has about 40 million transistors
z Ultra large scale integrationyOver 100,000,000 devices on a chip (vague term)
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Moore’s Lawz Increased density of components on chipz Gordon Moore : co-founder of Intelz Number of transistors on a chip will double every yearz Since 1970’s development has slowed a littleyNumber of transistors doubles every 18 months
z Cost of a chip has remained almost unchangedz Higher packing density means shorter electrical paths,
giving higher performancez Smaller size gives increased flexibilityz Reduced power and cooling requirementsz Fewer interconnections increases reliability
Growth in CPU Transistor Count
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IBM 360 series
z 1964z Replaced (& not compatible with) 7000 seriesyReason: Needed to break out of constraints of the 7000
architecture
z First planned “family” of computersySimilar or identical instruction setsySimilar or identical O/SyIncreasing speedyIncreasing number of I/O ports (i.e. more terminals)yIncreased memory size yIncreased cost (not always the case today!)
z Multiplexed switch structure
DEC PDP-8
z1964zFirst minicomputer (after miniskirt!)zDid not need air conditioned roomzSmall enough to sit on a lab benchz$16,000 y$100k+ for IBM 360
zEmbedded applications & OEMzBUS STRUCTURE
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DEC - PDP-8 Bus Structure
OMNIBUS
ConsoleController
CPU Main Memory I/OModule
I/OModule
96 separate signal paths to carry control, address, data signalsHighly flexible, allowed modules to be plugged in for different configurations
Other Innovations -Semiconductor Memory
z1970zFairchildzSize of a single coreyi.e. 1 bit of magnetic core storageyHeld 256 bits
zNon-destructive readzMuch faster than corezCapacity approximately doubles each year
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Intel
z 1971 - 4004 yFirst microprocessoryAll CPU components on a single chipy4 bit
z Followed in 1972 by 8008y8 bityBoth designed for specific applications
z 1974 - 8080yIntel’s first general purpose microprocessor
z Evolution: 8086, 8088, 80286, 80386, 80486, Pentium Pentium Pro, Pentium II, Pentium III, Pentium IV, Itanium
Speeding it up
zSmaller manufacturing process (0.11 micron)zPipeliningzOn board cachezOn board L1 & L2 cachezBranch predictionzData flow analysiszSpeculative executionzParallel execution
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Performance Mismatch
zProcessor speed increasedzMemory capacity increasedzMemory speed lags behind processor speed
zCommon memory chip technologyyDRAM = Dynamic Random Access Memory
DRAM and Processor Characteristics
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Trends in DRAM use
Solutions
z Increase number of bits retrieved at one timeyMake DRAM “wider” rather than “deeper”
z Change DRAM interfaceyCache
z Reduce frequency of memory accessyMore complex cache and cache on chip
z Increase interconnection bandwidthyHigh speed busesyHierarchy of buses
z Similar problems with I/O devices, e.g. graphics, networkz Need balance in computer design
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