Computer Architecture

1
Computer Architecture

• Part II-D Survey of Processor Architecture

2
Microprocessors in the Market
Whats the difference?
3
Areas of Development

• Below are technologies which can be improved in
  CPU design
• System bus speed
• Internal and external clock frequency
• Casing
• Cooling system
• Instruction set
• Material used for the die
• End result enhance speed of the CPU and the
  system in general

4
The System Bus

• Conduit for moving data between the processor and
  other system components

5
System Bus Speeds

• Intel Pentium Core 2 Quad/Duo have CPU clocks of
  2.66/3 GHz with system bus speeds of 1066/1333
  MHz
• AMD 2nd Generation Opteron (dual core) processor
  has clock speed of 1.8 GHz with a 1000 MHz system
  bus

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Split Clock Frequency

• Internal clock frequency
• Speed of data processing inside the CPU
• External clock frequency
• Speed of data transfer to and from the CPU via
  the system bus
• Intel 486DX2 25/50 was first to use clock
  doubling to implement split clock system

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The GHz Race in CPU Frequency

• June 1999 API (Alpha Processor Inc.)
  demonstrated a 1 GHz chip
• March 2000 AMD released Athlon 1 GHz within
  days Intel released 1 GHz Pentium III
• 2002 AMD, Intel uses 0.13 micron technology
• Athlon XP 2200 (June)
• Pentium 4 2.53 GHz (May), mobile Pentium 4 2 GHz
  (June)
• 2004
• Pentium 4 3.6 GHz, 800 MHz system bus
• AMD 3200, 2.2 GHz, 400 MHz Same as 2003
  32-bit CPUs ? now concentrating on 64-bit
• 2005
• Pentium 4 3.73 3.8 GHz, 800/1066 MHz system
  bus
• AMD Same as 2004

8
Is Moores Law Dead?

• Intels vision of a 10 GHz CPU cannot be realized
  due to heat problems
• Some have pushed speed limits through high-end
  cooling systems
• Both Intel and AMD no longer concentrating on
  speed as performance driver
• SIA says Moores Law is still going strong after
  40 years

9
Micron Technology

• A micron is 1 millionth of a meter
• Human hair strand about 100 microns
• Objective thinner wires
• Allow CPU to operate at lower voltage
• Results in CPU generating less heat and operating
  at higher speeds
• Currently, processors are in the range of 0.065
  microns (65 nm)
• Intels Roadmap 45 ? 15 nm

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Micron Technology Through the Years
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Thinner Wires Increased Transistors
Pertium 4 42,000,000
AMD K6 8,800,000
486SX/486DX 486DX2/486DX4 1,200,000
386DX/386SX 250,000
Pentium, Cyrix AMD K5, MMX 3,100,000
8086/8088 22,000
286 128,000
Athlon 1.4 GHz 37,000,000
12
The Switch to Copper

• Aluminum limits making chips smaller
• Copper is a good choice because it
• is a better conductor
• consumes less energy, and
• takes up less space than aluminum
• Copper allowed processors to boost speeds to the
  GHz range
• IBM pioneered the use of copper on September 1,
  1998 (IBM Power PC 740/750)

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PC on a Chip

• Integrates a number of key components into one
  chip
• Result The chip replaces dozen or so separate
  chips (memory, FPU, graphics, video, etc.)
• Applications PDAs, cellphones, set-top boxes,
  embedded processors, etc.

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Impact of PC-on-a-Chip

• Smaller and quieter desktops
• Battery of devices lasts longer because of the
  low power drain
• Proliferation of information appliances

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CPU Receptacle

• ZIF
• Zero Insertion Force socket - type of socket
  designed for easy insertion of chips that have
  high density of pins
• Socket 7 - popular implementation of ZIF

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CPU Receptacle

• Slot 1
• Consists of receptacle on the motherboard that
  holds an Intel Single Edge Contact (SEC)
  cartridge
• Cartridge may contain up to two CPUs and an L2
  cache (runs at half the speed of CPU) and plugs
  into 242-pin receptacle
• Started with Pentium II

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CPU Receptacle

• A Pentium II mounted on Slot 1

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CPU Receptacle

• Slot 2
• An enhanced Slot 1
• Uses 330-pin SEC
• Holds up to four CPUs
• L2 cache runs at full processor speed
• First used in Intel's Pentium II Xeon

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CPU Receptacle

• AMDs Slot A
• Receptacle on motherboard for K7 CPU
• Physically similar to Slot 1, but has different
  electrical requirements

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Casing FC-PGA (Flip-Chip)

• Traditional Wiring Flip-Chip (IBM)

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Advantages of FC-PGA

• Greater of I/O pins available
• Shorter electrical connections
• Better manufacturing efficiency

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Casing FC-LGA
Bottom view of LGA/BGA-based CPU
LGA Socket 775
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Advantages of FC-LGA

• Lower voltage used (less distance traveled,
  reduced signal loss)
• Less heat dissipation

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Cache

• Works as buffer between CPU and memory
• Two types
• Internal
• External

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Levels of Cache

• Level 1
• Level 2
• Level 3

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Cache Placement

• Intel used to have external L2 cache
• Pentium Pro
• Internal but CPU and L2 cache are separate
• Result larger chip that requires a larger socket

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Overclocking

• Going beyond recommended clock frequency settings
• 3 method of overclocking
• System bus frequency
• CPU frequency multiplier
• Change both of the above
• Some CPUs have locked frequencies

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Overclocking How to...

• Done through BIOS program
• Older systems require motherboard jumpers
• Some motherboards (e.g. ASUS TX97) contain jumper
  codes

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Overclocking Issues

• Heat!
• Can main memory cope?
• Will the software still work?

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Cooling Systems

• CPUs get hotter as they get faster
• Developed to keep the CPU from overheating
• Sophisticated cooling systems allow more reliable
  CPU operation

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Liquid Nitrogen Extremely Cool!
CPU Pentium 4 (Northwood) Date Christmas 2003
32
The CPU Gets Watered Down
33
Multimedia Processing

• Multimedia applications require geometric
  transformation
• Re-computation of location and size of an image
  to determine new position
• Deals with FP
• FPU handles all real number computations
• Drawing landscapes (e.g. games) involves lots of
  computations and CPU may not handle it as fast as
  the player could react

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Ways of Handling Multimedia

• Speed up the CPU
• Improve the CPUs FPU by adding more pipelines
• Use high-end 3D graphics cards
• Add new multimedia instructions

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Multimedia Innovations in CPUs

• MMX
• 3DNow!
• SSE

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MMX

• Introduced 1995 in the Pentium processor
• Had 57 new instructions for 3D graphics
• Introduced SIMD (Single Instruction Multiple
  Data) instructions technique that processes more
  than one integer simultaneously
• Problems
• Only works with integers
• CPU can only work with either MMX or FPU, not
  both simultaneously because they share registers

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3DNow!

• Introduced summer of 1998 in the AMD K6-2
• Characteristics
• Supports SIMD instructions
• Improved handling of numbers
• Successful!
• Integrated in Windows, games, and drivers
• Does not use the same registers

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SSE

• Introduced in Pentium III (Katmai) 500 MHz as
  Intels response to 3DNow!
• Characteristics
• 8 new 128-bit registers (can hold four 32-bit s)
• Has Streaming SIMD Extensions
• 50 new instructions enabling simultaneous
  advanced calculations of more FP with a single
  instruction
• New Media Instructions designed for coding and
  decoding MPEGs

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Problems with SSE

• Pipelines can only handle two 32-bit numbers at a
  time
• To take advantage of 128-bit registers, FPU
  pipeline should have been doubled (would have
  pushed back release date of Katmai)
• Potentially, it could have enhanced 3D graphics
  since registers can handle four 32-bit numbers at
  a time

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SSE Enhancements

• SSE2
• Started in Pentium 4
• Has 144 new instructions (since SSE)
• Data width now 64 bits
• SSE3
• 13 additional SIMD instructions (since SSE2)
• New instructions primarily designed to improve
  thread synchronization and specific application
  areas such as media and gaming
• Supplemental SSE3 (Core 2) ? SSE4

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Other CPU Innovations

• Data width
• Internal How many bits can the CPU process
  simultaneously?
• External How many bits can the CPU receive
  simultaneously for processing
• Superscalar architecture
• Superpipelined architecture

Superscalar processing
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Intel Corporation

• Produced biggest impact on microprocessor
  technology
• Main line of business is CPU but also has other
  hardware products (e.g. motherboards)

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Short History of Intel

• 1968 Birth of Intel
• Started in memory business
• First product was 64-bit memory
• 1970s Increase in market share
• Early 1980s Japanese eats up memory market with
  16 - 256 KB chips
• 1984 Business slowing down ? Get us out of
  memory!
• 1986 Exited from memory due to success of 80386

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Intel Processor Time Line
1982 286 16-bit processor Optimized Instruction
handling
1978 8086 First 16-bit CPU from Intel
1988 386SX Cheaper version of the 386DX
2
1979 8088 Reengineered CPU to fit existing 8-bit
hardware
1989 486 Built in math co-processor L1 cache
on-chip
1985 386 First 32-bit CPU (32-bit system bus)
1971 4004 Intels first microprocessor (108 KHz,
4 bit bus width)
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Intel Processor Time Line
May 7, 1997 Pentium II (Klamath) 512 KB L2 L1
cache of 32 KB
1993 Pentium Classic Superscalar (5x 486DX-33
MHz) Width of system bus 64 bit Speed of system
bus 60 to 66 MHz Initially produced a lot of heat
486SX Discount chip No math co-processor
Nov 1, 1995 Pentium Pro RISC Processor 32 bit
processing L2 cache is built in
3
486DX4 Triple the clock speed From 25 MHz to 75
MHz 33 MHz to 100 MHz
Jan 8, 1997 Pentium MMX New set of instructions
for multimedia 32 KB L1 cache
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Intel Processor Time Line
2000 Pentium 4 7th Generation 0.18 micron
technology
1998 Celeron (Mendocino) 333 MHz 128 KB L2
internal cache
Jan 26, 1998 Deschutes 333 MHz 0.25 micron
technology
1999 Pentim III (Katmai) Enhanced MMX2 graphics
instructions
Core (2005)
2001 Itanium (formerly Merced) 64-bit CPU 0.18
micron technology gt 25 million transistors
1Q 1998 Celeron (Covington) Pentium II
without the L2 cache
July 26, 1998 Pentium II Xeon 450 MHz Custom
SRAM Different L2 caches 512, 1/2 MB Can have 4
- 8 Xeons in one server
1999 Pentium III Xeon (Tanner)
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Current Intel CPU Innovations

• Hyperthreading
• Multi-core
• Core
• Core 2 (64-bit architecture)

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Intels First 64-Bit Chip (Server) Itanium

• Was known as IA-64 (but IA-32 compatible)
• EPIC (Explicitly Parallel Instruction Computing)
  processor
• Enables up to 20 operations/clock cycle
• Employs branch prediction and speculation
• Three levels of cache 2 MB / 4 MB L3 cache, 96K
  L2 cache, and 32K L1 cache
• 128 integer registers, 128 FP registers

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Itanium 2

• Available from 1 - 1.66 GHz
• Internal L3 cache (1.5 MB, 3 MB, 4 MB, 6 MB, or 9
  MB)
• System bus 400/533/667 MHz, 128-bits wide
• 0.13 microns, 592 million transistors
• Next version (Montecito) has 1.72 billion
  transistors, 26 MB on-die cache, 90 nm

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Current Intel CPU Lineup

• Mobile
• Centrino (Core and Core 2)
• Desktop
• Core 2 Extreme
• Core 2 (now used in Apple Mac Mini)
• Servers and workstations
• Xeon (now used in Apple Mac Pro)
• Itanium 2

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AMD (Advanced Micro Devices)

• Incorporated in May 1969
• Challenging Intel even before Pentium-class
  processors
• Offered their own technology and cannot be
  considered as producing clones
• Achieved increased market sales starting with K6
  and K6-II

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AMD Series (From Pentium Class)

• K5
• Similar to the classic Pentiums
• 16 KB L1 cache and no MMX
• Not very impressive but much cheaper than similar
  Pentium models
• K6
• Technology brought in from NexGen put AMD back
  in business
• 32 KB L1 cache MMX
• Pentium compatible but performed better than MMX

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AMD Series (From Pentium Class)

• K6-II Chomper
• 0.25 micron, system bus speed of 100 MHz
• Introduced 3DNow!
• Also MMX-compatible really challenged the
  Pentium II and led to low-cost Celeron
• K6-III Sharptooth
• Three levels of cache L1 and L2 are in CPU L3
  is on motherboard up to 1 MB 133 system bus
• Was not as successful as the K6-II
• K7 Athlon

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Last of AMDs 32-Bit Processors

• Athlon XP
• Intel played catch-up to the Athlon XP on many
  occasions, but now stagnant in 32-bit computing
• Model 3200 has a 2.2 GHz CPU, 3 FP pipelines,
  128 KB of L1 cache, 512 KB L2 cache, system bus
  speed of 400 MHz, and 0.13 micron technology
• Sempron
• Counterpart of Intel Celeron
• Model 3300 has 2 GHz CPU, 754-pins, 90 nm
  technology, 128 KB L2 cache

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AMDs 64-Bit Chips

• Varieties
• Athlon 64 (desktop)
• Turion 64 (mobile)
• Opteron (servers or workstations)
• Provides seamless transition to 64-bit
• System bus runs at processor speed through
  on-chip memory controller
• Lead the Itanium 2 on many benchmarks
• AMD formed a partnership with Sun

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Current AMD 64-Bit CPU Innovations

• HyperTransport
• Dual core
• Direct Connect Architecture

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Transmetas Crusoe Processor

• Transmetas founders include David Ditzel, Linus
  Torvalds, and Paul Allen released Crusoe in
  January 2000
• Architectural achievements
• Only 25 the number of transistors compared to
  current Pentiums
• Needs only 1 or 2 watts of power for 400 MHz or
  700 MHz chips running at full speed
• Much less heat dissipated but can compete with
  same category Intel and AMD chips

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How Crusoe Pulled It Off

• Efficient instruction set bears no resemblance to
  x86
• Takes advantage of latest and best in hardware
  design
• Software layer (code morphing software) in flash
  ROM translates x86 commands

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Current Transmeta Processors

• Crusoe TM5900
• 667 MHz 1 GHz CPU speed
• 128 KB L1, 512 KB L2
• 133 MHz system bus
• 0.13 microns
• Efficeon TM8800
• Up to 1.7 GHz
• 128 KB L1 instruction cache 64 KB L1 data cache,
  1 MB L2
• 400 MHz system bus

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The PowerPC Microprocessor

• Originally designed by Apple, IBM, and Motorola
• Based on IBM POWER architecture used in IBM
  RS/6000 (RISC based)
• Provides seamless transition to 64-bit
• The PowerPC G5 is used in Apple iMac G5
• 2.7 GHz CPU speed, 1.35 GHz system bus, 512 KB
  on-chip L2 cache

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Sun UltraSparc IV

• 2nd generation dual core processor design (1368
  pins FC-LGA)
• 64-bit CPU, 90 nm, 295 million transistors
• CPU speeds of 1.95 / 2.1 GHz
• 2 MB L2 cache, 32 MB off-chip
• On-chip memory controller
• CMT (Chip Multi-Threading) with 2 threads per
  processor
• 14-stage non-stalling pipeline
• 4-way superscalar
• Runs Solaris, Linux, FreeBSD, and other UNIX
  versions

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Sun UltraSparc T1

• Available in 4-, 6- or 8-core
• 64 bits, 90 nm
• 4-way multithreaded core
• 14-stage non-stalling pipeline
• 4 integrated memory controllers
• 16 KB instruction, 8 KB data L1 cache per core, 3
  MB unified L2 cache
• Available in 1 and 1.2 GHz
• Low power (72 79 watts)

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Multiprocessor Systems

• Combines two or more CPUs of the same brand and
  model
• Allows systems to scale up
• Forms an N-way system

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Future Trends

• In Dec. 1997, the Semiconductor Industry
  Association (SIA) provided details about future
  requirements of microprocessors.
• Attempts to continue the pace predicted by
  Moores Law

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1999 SIA Roadmap for Microprocessors
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International Technology Roadmap for
Semiconductors