01Introduction – Computer Evolution &

Performance

Computer Organization

Architecture & Organization 1Architecture is those attributes visible to the

programmerInstruction set, number of bits used for data

representation, I/O mechanisms, addressing techniques.

e.g. Is there a multiply instruction?Organization is how features are

implementedControl signals, interfaces, memory

technology.e.g. Is there a hardware multiply unit or is it

done by repeated addition?

Architecture & Organization 2All Intel x86 family share the same basic

architectureThe IBM System/370 family share the same

basic architecture

This gives code compatibilityAt least backwards (with some notes)Virtual machine?Emulator?

Organization differs between different versions

Structure & FunctionStructure is the way in which components

relate to each otherFunction is the operation of individual

components as part of the structure

FunctionAll computer functions are:

Data processingData storageData movementControl

Functional View

Operations (a) Data movement

Operations (b) Storage

Operation (c) Processing from/to storage

Operation (d)Processing from storage to I/O

Structure - Top Level

Computer

Main Memory

InputOutput

SystemsInterconnection

Peripherals

Communicationlines

CentralProcessing Unit

Computer

Structure - The CPU

Computer Arithmeticand Login Unit

ControlUnit

Internal CPUInterconnection

Registers

CPU

I/O

Memory

SystemBus

CPU

Structure - The Control Unit

CPU

ControlMemory

Control Unit Registers and Decoders

SequencingLogin

ControlUnit

ALU

Registers

InternalBus

Control Unit

ENIAC - backgroundElectronic Numerical Integrator And

ComputerEckert and MauchlyUniversity of PennsylvaniaTrajectory tables for weapons Started 1943Finished 1946

Too late for war effortUsed until 1955

ENIAC - detailsDecimal (not binary)20 accumulators of 10 digitsProgrammed manually by switches18,000 vacuum tubes30 tons15,000 square feet140 kW power consumption5,000 additions per second

von Neumann/TuringStored Program conceptMain memory storing programs and dataALU operating on binary dataControl unit interpreting instructions from

memory and executingInput and output equipment operated by

control unitPrinceton Institute for Advanced Studies

IASCompleted 1952

Structure of von Neumann machine

IAS - details1000 x 40 bit words

Binary number2 x 20 bit instructions

Set of registers (storage in CPU)Memory Buffer RegisterMemory Address RegisterInstruction RegisterInstruction Buffer RegisterProgram CounterAccumulatorMultiplier Quotient

Structure of IAS – detail

Commercial Computers1947 - Eckert-Mauchly Computer

CorporationUNIVAC I (Universal Automatic Computer)US Bureau of Census 1950 calculationsBecame part of Sperry-Rand CorporationLate 1950s - UNIVAC II

FasterMore memory

IBMPunched-card processing equipment1953 - the 701

IBM’s first stored program computerScientific calculations

1955 - the 702Business applications

Lead to 700/7000 series

TransistorsReplaced vacuum tubesSmallerCheaperLess heat dissipationSolid State deviceMade from Silicon (Sand)Invented 1947 at Bell LabsWilliam Shockley et al.

Transistor Based ComputersSecond generation machinesNCR & RCA produced small transistor

machinesIBM 7000DEC - 1957

Produced PDP-1

MicroelectronicsLiterally - “small electronics”A computer is made up of gates, memory

cells and interconnectionsThese can be manufactured on a

semiconductore.g. silicon wafer

Moore’s LawIncreased density of components on chipGordon Moore – co-founder of IntelNumber of transistors on a chip will double

every yearSince 1970’s development has slowed a little

Number of transistors doubles every 18 monthsCost of a chip has remained almost unchangedHigher packing density means shorter

electrical paths, giving higher performanceSmaller size gives increased flexibilityReduced power and cooling requirementsFewer interconnections increases reliability

Growth in CPU Transistor Count

IBM 360 series1964Replaced (& not compatible with) 7000 seriesFirst planned “family” of computers

Similar or identical instruction setsSimilar or identical O/SIncreasing speedIncreasing number of I/O ports (i.e. more

terminals)Increased memory size Increased cost

Multiplexed switch structure

DEC PDP-81964First minicomputerDid not need air conditioned roomSmall enough to sit on a lab bench$16,000

$100k+ for IBM 360Embedded applications & OEMBUS STRUCTURE

DEC - PDP-8 Bus Structure

Semiconductor Memory1970FairchildSize of a single core

i.e. 1 bit of magnetic core storageHolds 256 bitsNon-destructive readMuch faster than coreCapacity approximately doubles each year

Intel1971 - 4004

First microprocessorAll CPU components on a single chip4 bit

Followed in 1972 by 80088 bitBoth designed for specific applications

1974 - 8080Intel’s first general purpose microprocessor

Speeding it upPipeliningOn board cacheOn board L1 & L2 cacheBranch predictionData flow analysisSpeculative execution

Performance BalanceProcessor speed increasedMemory capacity increasedMemory speed lags behind processor speed

Processor and Memory Performance Gap

SolutionsIncrease number of bits retrieved at one

timeMake DRAM “wider” rather than “deeper”

Change DRAM interfaceCache

Reduce frequency of memory accessMore complex cache and cache on chip

Increase interconnection bandwidthHigh speed busesHierarchy of buses

I/O DevicesPeripherals with intensive I/O demandsLarge data throughput demandsProcessors can handle thisProblem moving data Solutions:

CachingBufferingHigher-speed interconnection busesMore elaborate bus structuresMultiple-processor configurations

Typical I/O Device Data Rates

Key is BalanceProcessor componentsMain memoryI/O devicesInterconnection structures

Intel Microprocessor Performance

New Approach – Multiple CoresMultiple processors on single chip

Large shared cacheWithin a processor, increase in performance

proportional to square root of increase in complexity

If software can use multiple processors, doubling number of processors almost doubles performance

So, use two simpler processors on the chip rather than one more complex processor

With two processors, larger caches are justifiedPower consumption of memory logic less than

processing logicExample: IBM POWER4

Two cores based on PowerPC

Pentium Evolution (1)8080

first general purpose microprocessor8 bit data pathUsed in first personal computer – Altair

8086much more powerful16 bit instruction cache, prefetch few instructions8088 (8 bit external bus) used in first IBM PC

8028616 Mbyte memory addressableup from 1Mb

8038632 bitSupport for multitasking

Pentium Evolution (2)80486

sophisticated powerful cache and instruction pipelining

built in maths co-processorPentium

SuperscalarMultiple instructions executed in parallel

Pentium ProIncreased superscalar organizationAggressive register renamingbranch predictiondata flow analysisspeculative execution

Pentium Evolution (3)Pentium II

MMX technologygraphics, video & audio processing

Pentium IIIAdditional floating point instructions for 3D graphics

Pentium 4Note Arabic rather than Roman numeralsFurther floating point and multimedia enhancements

Itanium64 bitsee chapter 15

Itanium 2Hardware enhancements to increase speed

See Intel web pages for detailed information on processors

Generations of ComputerVacuum tube - 1946-1957Transistor - 1958-1964Small scale integration - 1965 on

Up to 100 devices on a chipMedium scale integration - to 1971

100-3,000 devices on a chipLarge scale integration - 1971-1977

3,000 - 100,000 devices on a chipVery large scale integration - 1978 -1991

100,000 - 100,000,000 devices on a chipUltra large scale integration – 1991 -

Over 100,000,000 devices on a chip

ReferencesStallings W., Computer Organization and

Architecture, 7th Ed., 2006, Prentice Hall