Download 3| 2. The External Data Bus

Chapter 4, The Central Processing Unit
|1|
Chapter Overview
A.
B.
Microprocessors
Replacing and Upgrading a CPU
Chapter 4, Lesson 1
Microprocessors
|2|
1.
Microprocessor Basics
A.
B.
C.
|3|
2.
The External Data Bus
A.
B.
C.
D.
E.
F.
G.
|4|
3.
Components
How microprocessors work
PC microprocessor developments and features
A microprocessor is an integrated circuit that contains a complete CPU
on a single chip.
The external data bus is the primary route for data in a PC.
The width of the bus determines the amount of data flow.
Expansion slots act as “on ramps” for additional devices.
The computer uses the external data bus to move data between
components.
Coded messages are sent into or out of devices connected to the
external data bus.
The CPU turns the coded messages into data.
The CPU
A.
B.
C.
Is the computer component that performs arithmetic and logical
operations and decodes and executes instructions
Controls the operation of the computer
Includes the following main components:
1.
Transistors
a.
Small electronic switches
b.
On-off positions form the binary codes.
c.
Silicon is used to make most transistors.
2.
Integrated circuits
a.
Are electronic devices consisting of a number of miniature transistors
and other circuit elements such as resistors and capacitors
b.
Were developed in the 1950s by putting two transistors on one silicon
wafer
3.
Microprocessors
a.
1971: Intel ships the first commercial microprocessor, Model 4004.
b.
1972: Intel ships the 8008, which is used to build the first personal
computer.
c.
|5|
4.
Microprocessor Design
A.
B.
C.
D.
E.
|6|
5.
B.
C.
D.
6.
C.
7.
Instruction fetch: transfers data between itself and the memory section
Instruction decode: manipulates data in the memory section or stores it
internally
Instruction execution: transfers data between itself and I/O devices
PC Microprocessor Developments and Features
A.
2
RAM allows the CPU to place and retrieve data from any RAM location
at any time.
The address bus addresses segments of memory.
The external data bus transfers data between the processor and
memory subsystem.
The memory controller controls access to the memory subsystem.
How Microprocessors Work
A.
B.
|8|
Microprocessors usually include three subsystems:
1.
Control unit (CU)
a.
Allows CPU operations to be based in part on code provided by an
external program
b.
Extends the ability of a PC to use new hardware components
2.
Arithmetic Logic Unit (ALU), which handles basic computation
functions
3.
Input/output (I/O) unit, which fetches data and passes it to the
external bus
Registers provide temporary memory storage.
Codes transfer information to and from the CPU and other hardware.
The clock synchronizes all system activities.
Clock speed represents the fastest speed at which the CPU can reliably
operate.
Memory
A.
|7|
1974: Intel introduces the 8080, which becomes the core for the
Altair computer.
The six elements for gauging CPU performance are:
1.
Speed
2.
Number of transistors
3.
Size of internal registers
4.
Size of the external data bus
5.
Size of the address bus
6.
Amount of internal cache
Outline, Chapter 4
ALS: A+ Certification, Third Edition
B.
|9|
|10|
8.
The First Pentiums
A.
|11|
The birth of the PC
1.
The 8086 and 8088 addressed up to 16 KB of RAM running at
4.77 MHz to 8 MHz.
2.
The 80286 addressed up to 16 MB of RAM running at 10 MHz to
20 MHz.
a.
Introduced virtual memory support
b.
Introduced two operating modes: real mode and protected mode
3.
The 80386 addressed up to 4 GB of RAM running at 12 MHz to
40 MHz.
a.
Virtual real mode allowed the PC to run more than one program at
once.
b.
Intel and AMD produced faster versions.
4.
The 80486 addressed up to 4 GB of RAM running at 25 MHz to
133 MHz.
a.
Intel, AMD, and Cyrix produced versions of the chip.
b.
Introduced system memory management (SMM), which could extend
battery life
c.
Introduced internal clock doubling, which requires a heat sink or fan
to cool off the CPU
B.
C.
D.
Pentium (Series I)
1.
Runs at 60 MHz to 200 MHz
2.
Offers superscalar technology
a.
Includes two instruction pipelines, U and V, which allow the Pentium
to execute two instructions simultaneously
b.
The ability to execute instructions simultaneously is called
multithreading.
3.
The on-board cache features two 8-bit caches—one for data and one for
program code.
Pentium Pro
1.
Features a second cache memory chip
2.
Runs at 133 MHz to 200 MHz
Pentium MMX
1.
Features multimedia extensions (MMX) for graphics and games
2.
Runs at 166 MHz to 233 MHz
Pentium II
1.
Incorporates MMX technology and a high-speed cache memory chip
2.
Runs at 233 MHz to 450 MHz, with a 100-MHz system bus
3.
Enhancements include
a.
Multiple branch prediction
b.
Data-flow analysis
c.
SEC cartridge packaging
d.
512-KB L2 cache
e.
Error-correction coding functionality on the L2 cache bus
Outline, Chapter 4
ALS: A+ Certification, Third Edition
3
E.
F.
G.
H.
Celeron
1.
Is a low-cost version of the Pentium II
2.
Runs at 66 MHz system bus speed, 333 MHz to 500 MHz
Xeon
1.
Runs at 100-MHz system bus speed
2.
Features a larger internal cache (up to 2 MB)
Pentium III
1.
Runs at 450 MHz to 1 GHz
2.
Features system bus speeds between 100 MHz and 133 MHz
Motorola
1.
Industry mainstay CPU for Apple computers
2.
PowerPC processor developed jointly by IBM, Motorola, and Apple
Chapter 4, Lesson 2
Replacing and Upgrading a CPU
|12|
1.
Possible Upgrade Scenarios
A.
B.
|13|
2.
Inserting a CPU
A.
B.
4
Upgrading issues and decisions
Upgrade recommendations for existing CPUs
1.
8086/8088: cannot be upgraded
2.
80286 through 80486: generally better to replace the motherboard
3.
80386SX: generally better to replace the motherboard
4.
Pentium I: replace the motherboard, display adapter, and sound card.
5.
Pentium II: upgrade just the CPU, or upgrade the CPU, motherboard,
case, keyboard, and mouse.
6.
Pentium III: generally upgrade just the CPU.
Several types of CPU sockets are available:
1.
Low-insertion-force (LIF)
a.
Use a flathead screwdriver to pry evenly around the CPU.
2.
Zero-insertion-force (ZIF)
a.
Is the most popular mount for PCs with 486 and early Pentium CPUs
b.
Has a lever arm for simple removal and installation
3.
Single-edge connector (SEC / Slot 1)
a.
Usually used with Pentium II and III Series
b.
Be sure to mount the cooling system properly and check fan
operation before running the CPU.
Care when handling a CPU
1.
Watch out for electrostatic discharge (ESD), which can damage or
ruin a chip.
2.
Use a wrist-grounding strap or other approved antistatic device.
3.
Take care not to bend any pins.
4.
Ensure that the CPU is properly lined up.
Outline, Chapter 4
ALS: A+ Certification, Third Edition
|14|
Chapter Summary
A.
B.
C.
D.
E.
F.
Understanding processor development and progress is essential to
understanding how to mix older technology with new technology.
The three key elements for measuring a CPU’s performance are its
speed, address bus, and external data bus.
Key CPU developments since the 80286 processor include 32-bit
processing, memory improvements, advanced cache technology,
multithreading, and streamlined code handling.
Today’s standard processor is the Pentium III chip with speeds of
500 MHz and faster.
Replacing a CPU is usually a simple task.
You need to be very careful of ESD and potential pin damage when
handling a CPU.
Outline, Chapter 4
ALS: A+ Certification, Third Edition
5