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RecapRecap(from Previous (from Previous

Lecture)Lecture)

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Computer ArchitectureComputer Architecture•Computer Architecture involves 3 inter-

related components– Instruction set architecture (ISA): The actual

programmer-visible instruction set and serves as the boundary between the software and hardware.

– Organization: includes the high-level aspects of a computer’s design such as: The memory system, the bus structure, and the internal CPU unit.

– Hardware: Refers to the specifics of the machine such as detailed logic design and packaging technology.

Computer Computer ArchitectureArchitecture

TechnologyProgrammingLanguages

OperatingSystems History

Applications

Measurement &

Evaluation

Computer Architecture:• Instruction Set Design• Organization• Hardware

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Three Computing Markets Today

EmbeddedDesktop Server

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Desktop Computer Systems

• For “General-Purpose” Use– Word-Processing, Web surfing, Multimedia, etc.– Computation and Programming

• What’s in the box– Microprocessor– Memory - DRAM– Hard disk(s), CDROM/DVD, etc.– I/O - mouse, keyboard, video card, monitor, network,

etc.

• Important Issues:– Optimized for price-performance– Performance - how fast is “fast enough”?– Cost– Basic capabilities (and expandability)

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Server Computer Systems

• Large-Scale Services– File storage– Computation (e.g., supercomputers)– Transaction Processing, Web

• What’s in the Box(es)– Microprocessor(s)– Hard disks– Network Interface(s)

• Important issues:– Performance– Reliability, availability– Scalability

One Rack-Mount PC Unit(Google uses ~ 10,000)

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Embedded Computer Systems

• Computer as part of larger system– Consumer electronics, appliances– Networking, telecommunications– Automotive / aircraft control

• What’s in the box– Microcontroller / Microprocessor / System on Chip (SOC)– Memory: RAM, ROM; Disk– Special-purpose I/O (including analog stuff)

• Important issues– Cost, Power Consumption– Performance (against real-time constraints)– Reliability and Safety

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Trends in Computer ArchitecturesTrends in Computer Architectures

• Computer architectures has been advancing at a very fast rate

• These advances can be attributed to advances in technology as well as advances in computer design

– Advances in technology (e.g., microelectronics, VLSI, packaging, etc) have been fairly steady

– Advances in computer design (e.g., ISA, Cache, RAID, ILP, etc.) have a much bigger impact (This is the theme of this class).

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Trends in TechnologyTrends in Technology

• Trends in Technology followed closely Moore’s Law “Transistor density of chips doubles every 1.5-2.0 years”

• As a consequence of Moore’s Law:

– Processor speed doubles every 1.5-2.0 years

– DRAM size doubles every 1.5-2.0 years

– Etc.

• These constitute a targettarget that the computer industry aim for.

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Growth in processor performance

1

10

100

1000

10000

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

Pe

rfo

rma

nce

(vs. V

AX

-11

/78

0)

25%/year

52%/year

20%/year

• VAX : 25%/year 1978 to 1986• RISC + x86: 52%/year 1986 to 2002• RISC + x86: 20%/year 2002 to present

From Hennessy and Patterson, Computer Architecture: A Quantitative Approach, 4th edition, October, 2006

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Integrated Circuits Capacity

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Today: VLSI Microprocessors

Pentium® 442M transistors / 1.3-1.8GHz

49-55WL=180nm

Pentium® 4 “Northwood”55M transistors / 2-2.5GHz

55WL=130nm Area=131mm2

Process Shrinks

Pentium® 4 “Prescott”125M transistors / 2.8-3.4GHz

115WL=90nm Area=112mm2

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Today: VLSI Microprocessors

Intel Itanium® 2410M transistors / 1.3GHz / 130W

L=130nm Area=374mm2

Image source: Intel Corporation www.intel.com

Intel Core 2 Duo 291M transistors / 2.67GHz / 65W

L=65nm Area=143mm2

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MOORE’s MOORE’s LAWLAW

µProc60%/yr.(2X/1.5yr)

DRAM9%/yr.(2X/10 yrs)1

10

100

1000

198

0198

1 198

3198

4198

5 198

6198

7198

8198

9199

0199

1 199

2199

3199

4199

5199

6199

7199

8 199

9200

0

DRAM

CPU198

2

Processor-MemoryPerformance Gap:(grows 50% / year)

Per

form

ance

“Moore’s Law”

Processor-DRAM Memory Gap (latency)

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We need a balanced Computer System

Memory Bus [Bandwidth]

CPU

Memory SecondaryStorage

[Clock Period,CPI,

Instruction count]

[Capacity,Cycle Time]

[Capacity,Data Rate]

Computer System

Chain: As strong as its Weakest ring