Microprocessors
Chapter 3
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Overview
• In this chapter, you will learn how to
–
–
–
–
–
Identify the core components of a CPU
Describe the relationship of CPUs and RAM
Explain the varieties of modern CPUs
Identify specialty CPUs
Install and upgrade CPUs
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Central Processing Unit (CPU)
Core Components
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Concepts
• The CPU (Central Processing Unit) works
as a very powerful calculator
• CPUs are not very smart…just very fast
at manipulating zeroes and ones
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Man in the Box
• Visualize the CPU as a man in a box.
– He will gladly perform anything you want him to do,
but he can’t see or hear anything outside the box.
– How can we communicate with him?
Is anyone out
there?
We need some
way to talk to the
guy inside the box
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Talking to the Man
• Imagine 16 lights
– 8 on the inside and 8 on the outside
– When an inside light is on, the corresponding
outside light is on. We can switch these lights
on and off.
– This communication system is like the
external data bus
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Talking to the Man
• In reality, a lot of little wires flash on or
off
– Voltage is applied or not
– Represented not as on, on, off, off…
but as 1, 1, 0, 0…
On
On
Off
Off
Off
On
On
On
1
1
0
0
0
1
1
1
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
External Data Bus
• The CPU communicates with the outside
world using the external data bus (EDB)
– Instead of light bulbs, the EDB is made up of tiny
wires
– The state of a wire is expressed in a binary format,
with zeroes and ones
– Each discrete setting (series of zeroes and ones
representing the state of the wires) of the EDB is a
line of code in a program
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Registers
• Inside the box are registers (temporary storage
locations)
• The four general-purpose registers found in all
CPUs are AX, BX, CX, and DX
10000101
11001001
00110101
10100001
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Codebook
• The man in the box needs one more tool:
the codebook or instruction set
– Called machine language
– One command is a line of code
– The complete set of commands for a processor is
its instruction set
Instruction
1000 0000
1001 0000
1011 0000
1100 0000
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Meaning
Store next line in AX
Store next line in BX
Add AX to BX & store in AX
Place AX on EDB
Codebook (Instruction Set)
Instruction
1000 0000
1001 0000
1011 0000
1100 0000
1000 0000
0000 0001
1001 0000
0000 0010
1011 0000
1100 0000
Meaning
Store next line in AX
Store next line in BX
Add AX to BX & store in AX
Place AX on EDB
Instruction (store data in AX)
Data (number 1)
Instruction (store data in BX)
Data (number 2)
Instruction (add AX and BX and place in AX)
Place AX on EDB
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Clock
• The CPU does no work
until told to—even
though data may be on
the EDB
• You need a buzzer to
tell the man in the box
to start
– This is referred to as a
clock
– A clock is actually a
stream of pulses
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
z
z
10000101
00110101
Time to
work
10000101
00110101
Clock
• A clock cycle is the time taken by the
special wire to charge up
– The CPU needs at least two clock cycles to act on
each command
– A cycle is one complete up and down segment of
the sine wave
• The maximum number of clock cycles
that can be handled by the CPU is called
the clock speed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
System Crystal
• The system crystal defines the speed at
which the CPU and the rest of the PC
operate
– Quartz oscillator, usually soldered to the
motherboard
• Overheating results from overclocking
the CPU (running it faster than its
maximum clock speed)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
In Summary
• The CPU is like a man in a box
• The external data bus gets data in and out of
the CPU
• Registers are used as temporary storage
inside the CPU
• The instruction set is like a codebook
• The clock defines the speed of the CPU
10000101
11001001
00110101
10100001
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Memory
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Memory
• Memory is a device that holds binary data
• Memory was first stored on paper cards and
then on magnetic cards and magnetic tapes
• Problems
– Serial access
– Slow
• Random access memory (RAM) to the rescue!
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAM
• RAM is organized similar to a spreadsheet
• Data can be read or written to by addressing
the RAM location
• Typically represented as KB, MB, or GB
• Volatile—zeroes out
when power lost
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Memory Controller Chip
• The memory controller chip (MCC) is a
device that facilitates the flow of data
from the RAM to the CPU
MCC
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Address Bus
• The address bus
enables the CPU to
control the MCC
– Another set of wires
in addition to the
external data bus
– Used by the CPU to
tell the Northbridge
which line of code it
wants from RAM
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
MCC
Address Bus
• The number of wires in the address bus
determines the maximum amount of
RAM the CPU can handle
– An 8088 had 20 wires, which provided 220
combinations (1,048,576 or 1 MB)
– Many current CPUs use 36 wires, which
provide 236 combinations (68,718,476,736 or
64 GB)
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Terminology
• Bits are represented as b (i.e., Kb)
• Bytes are represented as B (i.e., KB)
K
Kilo
210
M
Mega
220
G
Giga
230
T
Tera
240
1024
about 1000
1,048,576
about 1 million
1,073,741,824
about 1 billion
1,099,511,627,776
about 1 trillion
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
210
220
230
240
Decimal Compared to Binary
643 Decimal
101 Binary
102
101
100
22
21
20
100
10
1
4
2
1
6
4
3
0
1
1
600 +
40 +
3
643
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
4+
0+
1+
5 Decimal
CompTIA A+
Essentials
Modern CPUs
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
CPU Overview
• Several specification are used to
describe and compare CPUs:
–
–
–
–
–
–
–
–
–
Make (Intel, AMD)
Model (Pentium, Athlon, etc.)
Packages, or how it’s mounted (PGA, SEC, SEP)
External speed (speed of crystal)
Multiplier (applied to crystal)
Cache (L1 and L2)
Internal speed (speed when crystal multiplied)
Pipelining
Hyper-threading
• We’ll cover these in older and newer
CPUs
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Manufacturers
• Two main CPU makers
– Intel
– AMD
• CPUs might look similar, but they are not
interchangeable
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Common CPU Packages
• Pin grid array (PGA)
– Most common
– Number of pins vary by processor
– Plugs into sockets that vary by processor
• Single edge cartridge (SEC)
– Single edge processor (SEP) is similar
– Processor mounted on board
– Board plugs into motherboard
• Zero insertion force (ZIF)
– Allows processor to be easily inserted
– Arm locks processor in place
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pentium CPU—The Early Years
• CPU makers have added a large number
of improvements over the years
– Larger external data buses
– Larger address buses
– Faster clock speeds
• Intel introduced the Pentium CPU in the
early 1990s
–
–
–
–
–
32-bit registers
Speeds up to 300 MHz
Ability to run multiple programs at once
Access super-fast cache RAM
Processes two or more lines of code at the same
time
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32-bit Addressing
• Current operating systems are referred
to as 32-bit (232)
– Can directly address 4 GB of memory
• Early Pentiums had 32-bit address bus
• Newer CPUs have 36-bit address bus
– 236 allows addressing 64 GB of RAM
– Some 32-bit operating systems address the extra
memory via “extensions”
– Memory is swapped in and out of the 4 GB base as
needed
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pipelining
• A pipeline is a series of steps taken by the
CPU to process a command
• Pipelining is the process of processing more
than one command at a time through the
use of separate sets of circuitry
– Works like an assembly line
– Commands go through the processor on a
“conveyer belt”
– Enables the processor to work on more than one
thing at a time
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Cache
• Cache is separate storage
area used for quick access
of data
– CPU runs faster than RAM
– Using a faster RAM cache
close to the CPU helps the
CPU run without waiting
RAM
1011 0101
1100 1010
1001 1111
1100 0111
1101 1101
0001 1101
1011 0110
1001 0001
CPU
– L1: close to the CPU and
fastest
– L2: faster than RAM
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAM Cache
L2 Cache
• L2 was originally on
the motherboard
– Referred to as external
cache
– Not uncommon on
today’s CPUs
• Size of the cache
varies from 0 to
1 MB
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Clock Speed and Multipliers
• The clock is derived from
the crystal
– Referred to as external
speed
• Clock is multiplied and
CPU runs at quicker
speed
Original clock
– CPU runs at much quicker
multiplied speed
• 66 MHz crystal
• Sent through a 2X multiplier
• Gives a 132 MHZ CPU
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Clock with 2x multiplier
Has twice as many cycles
for CPU to operate with
CPU Voltages
• Older CPUs needed 5 volts
– CPU voltage was reduced to 3.3 volts
• Later improvements reduced voltage
even more with no single standard
– Smaller size resulted in lower voltage and smaller
chips
– Voltage regulator module (VRM) is a small card
that enables a CPU to standardize voltage
regulators
– CPU reports voltage requirements with CPUID
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Older CPUs
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
Remarks
Early
Pentiums
50–66 MHz
60–200 MHz
1x to 3x
16 KB
PGA
Socket 4, 5
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
AMD K5
Pentium
Pro
50–75 MHz
60–66 MHz
60–150 MHz 166–200 MHz
1.5x to 2x
2.5x to 3x
16 KB
16 KB
256 KB,
512 KB, 1 MB
PGA
PGA
Socket 7
Socket 8
High-end
systems
Improvements
• Out-of-order processing
– Enabled processors to predict data that was needed
– 90% accuracy in pulling the correct data
• On-chip L2 cache
– On the same package, but not necessarily on the
same chip
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Bus Types
• Frontside bus
– Address bus and external data bus are combined
together between the CPU, MCC, and RAM
• Backside bus
– Connection between the CPU and L2 cache
• Remember that L2 cache used to be external cache but is
now internal to the CPU housing
CPU
Backside
bus
MCC
L2 Cache
Frontside bus
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
RAM
Older CPUs
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
Remarks
Later
Pentiums
66–75 MHz
166–200 MHz
2.5x to 4.5x
32 KB
PGA
Socket 7
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Pentium II AMD K6
66–100 MHz
233–450 MHz
3.5x to 4.5x
32 KB
512 KB
SEC
Slot 1
AMD & Intel
Split
60–100 MHz
200– 550 MHz
3.5x to 5.5x
32 or 64 KB
0 to 256 KB
PGA
Socket 7
Pentium Improvements
• MMX (multimedia extensions)
– Designed for graphical applications
• Increased clocks and multipliers
– Up to 4.5x
• Pentium II
– Faster than Pentium Pro
– Used SEC
• AMD K6
– Proprietary 3DNow!
– Requires a Super Socket 7
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Older CPUs
Ext. speed
Int. speed
Intel Celeron
(P II)
66 MHz
266–700 MHz
Multiplier
L1
4x to 10.5x
32 KB
Pentium III AMD
Athlons
100–133 MHz 100–133 MHz
450 MHz–1.2
500MHz–
GHz
1GHz
4x to 10x
5x to 10x
32 KB
128 KB
L2
Package
Socket
0 to 128 KB
SEP, PGA
Slot 1,
Socket 370
256–512 KB
SEC-2, PGA
Slot 1,
Socket 370
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512 KB
SEC
Slot A7
Older CPUs
• Celeron
– Offshoot of Pentium II for
the low-end PC
• Pentium III
– Intel’s answer to 3DNow!
by AMD
• AMD Athlon
– SEC package used slot A
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
More Current CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
AMD Athlon
Thunderbird
180 nm
38–75
100–133 MHz
650 MHz–
1.4 GHz
6.5x to 14x
128 KB
256 KB
PGA
Socket A
AMD Duron
180 nm
21–57
100 MHz
650 MHz–
1.8 GHz
6.5x to 13.5x
128 KB
64 KB
PGA
Socket A
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pentium 4
Willamette
180 nm
49–100
100–133 MHz
1.3–2 GHz
13x to 20x
128 KB
256 KB
PGA
Socket 423 or 478
IT Technician
CompTIA A+
Technician
Processing and Wattage
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Processing and Wattage
• Wattage is a measure of power
– Goal is to consume as little power as possible
while still having a powerful CPU
– Solution: make it smaller so it takes less voltage;
less voltage is less wattage
• Processing
– Measures thickness of wafers
– Some of today’s processors are 65 nanometers
• About as thick as 455 hydrogen atoms
• Or 1/3077th of the width of a human hair
Hydrogen atom
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pentium Competitors
• AMD Athlon Thunderbird
– Double-pumped frontside bus doubled the data rate
without increasing the clock speed
– Returned to PGA with Socket A
• AMD Duron
– Generic name given to all lower-end Athlon processors
– AMD’s competitor to Intel’s Celeron for the low-end PC
• Intel Pentium 4 (Willamette)
– Completely redesigned core called NetBurst
– Used 20-step pipeline
– Quad-pumped frontside bus
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
More Current CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
AMD Athlon
Palomino
180 nm
60–72
133 MHz
1.3–2.2 GHz
13x to 16.5x
128 KB
256–512 KB
PGA
Socket A
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
AMD Athlon
Thoroughbred
150 nm
49–70
166 MHz
1.3–2.2 GHz
13x to 16.5x
128 KB
256–512 KB
PGA
Socket A
More Current CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
Pentium 4
Northwood
130 nm
45–68
100 MHz
1.3–3.8 GHz
13x to 23x
128 KB
256, 512 KB
PGA
Socket 478 or
775
Pentium 4
Prescott
90 nm
~84
133 MHz
1.3–3.8 GHz
13x to 23x
128 KB
256, 512 KB
PGA
Socket 478 or
775
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pentium 4
Cedar Mill
65 nm
86
200 MHz
1.3–3.8 GHz
13x to 23x
128 KB
256, 512 KB
PGA
Socket 478 or
775
Newer Processors
• AMD Athlon XP (Palomino and Thoroughbred)
– Enhanced version of the Athlon core processor
• Intel Pentium 4 (Northwood, Prescott, Cedar
Mill)
– Increased frontside bus to 800 MHz
– Introduced hyperthreading
• Hyperthreading
– Looks like two CPUs
to the operating system
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
More Current CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
AMD Athlon XP
Palomino
180 nm
60–72
133 MHz
1.3–2.2 GHz
13x to 16.5x
128 KB
256–512 KB
PGA
Socket A
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
AMD Athlon
Thoroughbred
150 nm
49–70
166 MHz
1.3–2.2 GHz
13x to 16.5x
128 KB
256–512 KB
PGA
Socket A
More Current CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
L3
Package
Socket
Athlon XP
Thorton/Barton
130 nm
60–70
133, 166, 200 MHz
1.6–2.2 GHz
10x to 16x
128 KB
256, 512 KB
PGA
Socket A
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Pentium 4
Extreme Edition
130, 90 nm
85–115
200, 266 MHz
3.2–3.7 GHz
14x to 17x
128 KB
512 KB
2 MB
PGA
Socket 478 or 775
Mobile Processors
• Mobile processors
– For laptops
– Use less power to overcome problems of heat and
power requirements
• Utilize throttling
– Previously called system management mode
(SMM)
– Allows a CPU to slow down during low demand
times
– Intel calls it SpeedStep
– AMD calls it PowerNow!
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
More Processors
• Intel Xeon processors
–
–
–
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Series of powerful CPUs
Massive L2 caches
Xeon is codeword for high-end
Can easily be used in symmetric multiprocessing
systems (multiple physical processors)
– Early Xeon used slots
– Later Xeons went back to PGA packages
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
64-Bit Processors
• 64-bit processing refers to a 64-bit
address bus
– We already had 64-bit external data buses
• Intel Itanium processors
– Itanium was Intel’s first 64-bit chip
– Itanium II is made for the PC
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
64-Bit Processors
• AMD Opteron processor
– Runs both 32-bit and 64-bit code
• Athlon 64
– First desktop 64-bit processor
– Backward-compatible with 32-bit programs
– Two main groups (130 nm and 90 nm)
• AMD Sempron CPUs
– Less cache than the Athlon 64
– Offer a tradeoff between price and performance
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Dual-core CPUs
• Due to practical limit of ~4 GHz in clock
speeds, alternatives were sought
• Dual core features two CPUs on same
chip
– Pentium D
– Athlon Dual Cores
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Dual-core CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
Pentium D
Smtihfield/Presler
90, 65 nm
95–130
166, 200 MHz
2.6–3.6 GHz
14x to 20x
Two 128 KB
Two 1 or 2 MB
775 LGA
Socket LGA 775
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Athlon Dual Core
90 nm
89–110
200 MHz
2–2.4 GHz
10x to 12x
128 KB
Two 512 KB or 1 MB
PGA
Socket 939 or AM2
Intel Core CPUs
Codename
Process
Wattage
Ext. speed
Int. speed
Multiplier
L1
L2
Package
Socket
Intel Core
Yonah
90, 65 nm
95–130
166, 200 MHz
2.6–3.6 GHz
14x to 20x
Two 128 KB
Two 1 or 2 MB
775 LGA
Socket LGA 775
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Intel Core 2
90 nm
89–110
200 MHz
2–2.4 GHz
10x to 12x
128 KB
Two 512 KB or 1 MB
PGA
Socket 939 or AM2
Installing CPUs
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Why Replace a CPU?
• Cost
– Chances are you’ll need to replace the
motherboard as well as the CPU—is it worth it?
• Cooling
– Faster CPUs will probably need better cooling
• Performance
– Faster CPUs may not be the best answer to
speeding up your PC
• Many times you really need more RAM
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Right CPU
• Consult your motherboard manual
– You need a CPU that will fit
in the socket or slot on
your motherboard
• Buying a CPU
– Most stores will not accept
returns
– Retail-boxed CPUs are genuine and come
with a fan
– Lots of illegal CPUs on the market
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
CPU Installation Guidelines
• Don’t touch the
pins (ESD)
• Match the notch
and dot printed on
the corners of the
CPU…they must
line up
– Incorrectly
installing your CPU
may destroy the
CPU and/or
motherboard!
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
CPU Installation Guidelines
• Use a heat sink
compound
• Install a fan on top
of the CPU after the
CPU has been
inserted into the
socket
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Plugging in the CPU Fan
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
The Art of Cooling
• Modern CPUs need to be
kept cool
– OEM fans are included in
retail-boxed CPUs
– Specialized fans usually
exceed OEM fans
– Liquid cooling works by
running a liquid (usually
water) through a metal block
that sits on top of your CPU
to absorb heat
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
Overclocking
• Overclocking is running a CPU at a
speed higher than rated
– Voids the warranty
– Black market exists
© 2007 The McGraw-Hill Companies, Inc. All rights reserved
© 2007 The McGraw-Hill Companies, Inc. All rights reserved