Processors

1
Processors

• Based in part on Chapter 4 from
• PC Hardware in a Nutshell
• (Thompson and Thompson)
• And information from
• http//www.intel.com/intel/intelis/museum/exhibit/
  hist_micro/index.htm

2
CPU

• The Central Processing Unit (CPU) is the brain
  of the computer.
• The CPU can be thought in terms of two basic
  pieces
• The Arithmetic Logic Unit (ALU) which modifies
  data by executing arithmetic and/or logical
  operations on it.
• The Control Unit which takes the instructions
  from memory, decodes it, and then moves the data
  to the appropriate places and ensures that the
  ALU performs the desired operation.

3
Generations

• The CPU is often just called the processor.
• For the ENIAC and other computers of the first
  generation, the processor was comprised of vacuum
  tubes.
• The processors individual vacuum tubes were
  replaced by individual transistors in the second
  generation of computers.
• Several transistors could be placed close
  together on an integrated circuit (IC) or chip.
  In third generation computers the processor
  consisted of several ICs.

4
Processor ? Microprocessor

• Eventually the entire processor was placed on a
  single chip. When this became standard computers
  were said to enter the fourth generation.
• In this case, the processor is known as a
  microprocessor.
• Some large machines today may have the processor
  spread over more than chip. But PCs typically
  have a single processor.

5
Tubes

• A computer of the first generation consisted of
  tubes.
• Tubes started with an effect Thomas Edison
  noticed while experimenting with light bulbs.
• John Ambrose Fleming discovered that one could
  exploit the effect to detect radio waves and
  convert them to electricity, but the signal was
  too small.
• Lee de Forest added to the device, making the
  triode Edwin Armstrong pointed out it could be
  used to amplify signals.

6
Transistors

• A computer of the second generation consisted of
  transistors.
• William Shockley, John Bardeen and Walter
  Brattain developed the transistor while working
  at Bell Labs in 1947. (Nobel Prize 1956)
• The transistor could play the same role as the
  vacuum tube but was significantly smaller and
  thus faster and less power consuming.

7
Integrated Circuit

• A computer of third generation consisted of
  integrated circuits.
• The problem with computers is that they required
  so many transistors connected to one another
  the so-called tyranny of numbers.
• This problem was solved by the monolithic idea
  the idea the many circuit elements (mainly
  transistors) could be placed on the same piece of
  semiconductor, i.e. an integrated circuit (IC).
• In 1958 Jack Kilby of Texas Instruments invented
  the IC. In 1959 Robert Noyce of Fairchild
  Semiconductor independently developed a
  better-designed IC. (Nobel Prize 2000.)

8
Microprocessor

• A computer of fourth generation has a
  microprocessor.
• What distinguishes a microprocessor from other
  integrated circuits is that a microprocessor can
  be programmed.
• So along with the idea of the microprocessor
  comes the idea of the instruction set the set
  of actions the programmer can have the
  microprocessor perform.

9
Intel
Noyce
Moore

• Intel was founded by Bob Noyce and Gordon Moore
  who formerly worked for Fairchild Semiconductor.
• In a collaboration between Busicom (a Japanese
  firm) and Intel to make calculators, Ted Hoff
  devises a plan to put all the main circuitry on
  one chip instead of the original plan of twelve
  (in 1968).
• The microprocessor was born.

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The Microprocessor is born
Intel made the 4004 (the first microprocessor)
for Busicom. Knowing they had a good thing, they
bought the rights to the 4004 from Busicom for
60,000.
Ted Hoff
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4004
12
4004

• The 4004 was introduced in November 1971.
• It was the first commercial microprocessor.
• It had 2,300 transistors and could execute
  approximately 60,000 instructions per second.
• Compare that to todays microprocessors, which
  have both the number of transistors and the
  number of instructions per second are in the
  millions.
• Moores law in action.

13
4004 Specs

• Clock speed Initially 108 kHz but upped to
  500kHz and then to 740kHz.
• Bus width 4 bits (though its instructions were 8
  bits)
• It addressed up to 1 Kb of program memory and up
  to 4 Kb of data memory.
• The program memory and data memory were separate.
• There were sixteen 4-bit (or eight 8-bit) general
  purpose registers.
• Executed 45 instructions.

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Relative Processor size
This diagram shows the relative sizes of the
Intel family of microprocessors. While the number
of transistors has grown substantially the size
of the chip has not imply that the density (the
number of transistors per area) has increased
dramatically.
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8008 Double your pleasure, double your fun

• The first 8-bit microprocessor.
• Actually work began on the 8008 before the 4004
  but it took longer to finish.
• Differs architecturally from the 4004. The
  microprocessors that follow were based on (and
  backward compatible with) the 8008.
• The 8008 was used in the Mark-8, one of the first
  home computers. 

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Mark-8
1During those days another large crowd gathered.
Since they had nothing to eat, Jesus called his
disciples to him and said, 2"I have compassion
for these people they have already been with me
three days and have nothing to eat. 3If I send
them home hungry, they will collapse on the way,
because some of them have come a long distance."
4His disciples answered, "But where in this
remote place can anyone get enough bread to feed
them?" 5"How many loaves do you have?" Jesus
asked. "Seven," they replied. 6He told the
crowd to sit down on the ground. When he had
taken the seven loaves and given thanks, he broke
them and gave them to his disciples to set before
the people, and they did so. 7They had a few
small fish as well he gave thanks for them also
and told the disciples to distribute them. 8The
people ate and were satisfied. Afterward the
disciples picked up seven basketfuls of broken
pieces that were left over. 9About four thousand
men were present.
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8080
18
8080

• Federico Faggin, who was involved with both the
  4004 and the 8008 (and would eventually leave to
  found Zilog) was as the lead designer for the
  8080.
• The 8080, released in 1974, was used in the first
  widely known personal computer the Altair.
• The Altair is said to have gotten its name from
  the destination of the Starship Enterprise from
  the Star Trek television show.
• Hobbyists could buy the Altair kit for 395.

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8080 Specs

• 16-bit address bus and an 8-bit data bus.
• Seven 8-bit registers (A-E, H, L)
• Pairs BC, DE and HL could be combined to make
  16-bit registers.
• A 16-bit stack pointer.
• A 16-bit program counter.
• Several I/O ports.

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8088
21
8086 8088

• Used in early word processors (Display-Writer and
  DataMaster).
• Used in IBMs first personal computer IBM PC/XT
  and its clone the Compaq DeskPro.
• PCs were moving out of the basements and into
  offices.
• Intel becomes a Fortune 500 company. They were
  named one of the "Business Triumphs of the
  Seventies by Fortune magazine.

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Display-Writer and IBM PC/XT
23
FPU

• Floating point operations are more tedious to
  perform than integer operations.
• The floating point unit (FPU) is circuitry
  devoted to floating point operations.
• In processors of the 8086 generation, the FPU was
  not standard but could be purchased as a separate
  chip (known in this case as a Math co-processor).
  
• In modern processors, the FPU can also help with
  multimedia and communications.

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286 a.k.a. 80286
25
286

• The 286, a.k.a. the 80286, was the first
  microprocessor in the Intel family that could
  execute all the code written for its predecessor
  (8086).
• Backward compatibility is an important feature of
  the Intel family of microprocessors.
• Six years after its release (1982), there were
  about 15 million 286-based PCs being used.

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286 Specs

• Executed instructions five time faster than 8086
  at the same clock speed.
• Addressable memory increased from 1 MB to 16 MB.
• The FPU (in this case 80287) remained separate.
• Introduced protected mode.

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Protected mode

• Allows multi-tasking so that the processor can
  juggle more than one program at a time.
• Each program is assigned to a certain range of
  memory. Only that program can use that range of
  memory. It is protected from interference by
  other programs. And other programs are protected
  form it.
• Uses extended memory and virtual memory so that a
  program seems to have access to more memory than
  it is assigned.

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386
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386

• Contains 275,000 transistors.
• Recall the 4004 had 2,300.
• 32-bit address bus and 32-bit data bus.
• Allowed multi-tasking.
• FPU still separate (80387).
• L1 cache a unit of fast memory included on the
  microprocessor.

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Levels of cache

• At the microprocessor level, cache refers units
  of SRAM used to speed up the processors
  interaction with memory.
• Level 1 (L1) or primary cache is built onto the
  processor chip.
• Level 2 (L2) or secondary cache originally was
  packaged separately from the processor (so one
  could change the amount of it) but started to be
  included as part of the processor package (around
  the time of the Pentium II).
• In the latter case, one can have Level 3 (L3)
  cache which is separate from the processor
  package.

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486
32
486

• Released 1989.
• 486 not 80486.
• 32-bit bus.
• 8 KB to 16 KB of cache (L1).
• 20 MHz to 50 MHz.
• Built-in FPU.
• Processor ran faster (a multiple of) the memory
  bus speed.
• Allowed the move from command-line OS to GUI OS
  (DOS to Windows).

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Pentinum
34
Pentium

• Released 1993.
• About 3.1 million transistors
• Upped memory bus speeds to 60 MHz or 66 MHz.
• Intel stopped using numbers because they could
  not register a number as a trademark.
• CISC (Complex Instruction Set Computer)
• 64-bit databus

35
Lowering the voltage

• More and more transistors with current flowing
  through them in a small amount of space means
  more and more heat is being generated.
• One development in microprocessors was a
  reduction of standard voltage at which the
  transistors function.
• Lower the voltage means reducing the heat and the
  power consumption. It can also affect speed and
  accuracy because the voltage ranges for a valid 1
  or 0 have been reduced.
• With some Pentiums, the long-standing standard of
  5 volts was reduced to 3.3 volts.

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About instructions

• The execution of a typical instruction involves
• Fetching the instruction from memory.
• Decoding the instruction.
• Fetching data necessary to execute the
  instruction.
• Executing the instruction.
• Placing the answer in the appropriate place.
• (Looking interrupts).
• One can gain speed by having consecutive
  instructions in different stages (have
  instructions in the pipeline).

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Branch prediction

• Pre-processing consecutive instructions will not
  help with speed when the next instruction to be
  executed is not the next instruction in the
  program (ifs, loops, subroutines, etc.)
• This situation is known as branching.
• Starting with some Pentiums, microprocessors
  included a branch prediction feature.

38
MMX/SIMD

• Some Pentiums have MMX.
• MultiMedia eXtensions?
• Matrix Math eXtensions?
• 57 additional instructions for making audio and
  video more efficient.
• Some Pentiums have Single Instruction Multiple
  Data (SIMD).
• One instruction can be used to operate on many
  pieces of data in parallel.

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Pentium Pro
40
Pentium Pro

• Released 1995
• 5.5 million transistors.
• Designed for the 32-bit server and workstation
  applications.
• Super-pipelining determines which instructions
  can be done out of order so less time is
  wasted.
• Introduced L2 cache (a separate cache memory
  chip).
• RISC (Reduced Instruction Set Computer)
  architecture.

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Pentium II
42
Pentium II

• Released in 1997.
• 7.5 million transistors.
• MMX technology.
• Designed specifically to process multimedia
  information (video, audio and graphics)
  efficiently.
• Introduced the Single Edge Contact (S.E.C.)
  Cartridge that also incorporated a high-speed
  cache memory chip.

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Pentium II Xeon
44
Pentium II Xeon

• Intel introduced high-end and low-end variations
  on its chip designs.
• The Xeon was used for mid-range and higher
  servers and workstations.
• For workstations and servers that utilize
  demanding business applications such as Internet
  services, corporate data warehousing, digital
  content creation, and electronic and mechanical
  design automation.
• Allows scaling using several processors
  together.

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Celeron
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Celeron

• Released in 1998.
• A cheaper version on the Pentium II
• Lower clock speeds
• Less Cache

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Pentium III
48
Pentium III

• Released in 1999.
• 9.5 million transistors.
• 0.25-micron technology.
• A micron is a millionth (10-6) of a meter.
• Recall that the number of transistors is going up
  but the chip size is not changing much.
  Therefore the transistors are getting smaller.
• 0.25-micron technology refers to the ability to
  manufacture chip having components (mainly
  transistors) whose length is no bigger than a
  0.25 microns.

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Pentium III

• Has 70 new instructions Internet Streaming SIMD
  (Single Instruction, Multiple Data) extensions
  to improve imaging, streaming audio, video and
  speech recognition applications.
• Designed to better the Internet experience. E.g.
  it allows users to browse through realistic
  online museums and stores or download
  high-quality video.

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Pentium III Xeon

• 1999
• PIII for workstations and servers.
• Has SIMD features.
• Improved cache speeds.
• Easily incorporated into multiprocessor
  configurations.

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Pentium 4
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Pentium 4

• 42 million transistors.
• Debuted with processor speeds of 1.5 gigahertz
  (1.5 billion hertz).

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Intel Xeon

• 2001.
• For workstations and servers.
• Based on Intel NetBurst architecture, which is
  designed to deliver the processing power needed
  for video and audio applications, advanced
  Internet technologies, and complex 3-D graphics.

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Itanium Processor

• 2001.
• Full 64-bit capability.
• For high-end, enterprise-class servers and
  workstations.
• The processor was built from the ground up with
  an entirely new architecture based on Intel's
  Explicitly Parallel Instruction Computing (EPIC)
  design technology.

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Moores Law
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References

• PC Hardware in a Nutshell, Thompson and Thompson
• http//www.intel.com/intel/intelis/museum/exhibit/
  hist_micro/index.htm
• http//antiquetech.com/chips/chips.htm
• http//www.webopedia.com
• The Chip, T. R. Reid (Random House, 2001)