Download Unit 2 Hardware Systems

Unit 2 Hardware Systems
Goals:
1. Learn about how the computer processes information and how memory works.
2. Learn about how data can be moved among components inside and outside the system unit.
3. Learn about the different media for storing data.
4. Understand how a computer works.
The microprocessor, also called the processor, is the main component that executes instructions stored in
the main memory. The microprocessor is sometimes referred to as the "brain" of the computer system,
making decisions and sending commands to the other components to complete a set of instructions. The
main memory stores instructions to be executed by the microprocessor. The data stored in main memory is
lost when the computer is turned off. In contrast to main memory, storage devices such as CD-ROM
drives and floppy disk drives store data permanently even when the computer is turned off.
Peripherals enable data input and output. Examples of peripheral devices include the monitor, the printer,
the keyboard, and the mouse. The peripherals also include mechanisms that allow data to be transferred in
and out of a computer system.
The chipset acts as the traffic cop controlling the flow of data and coordinating interactions among
components in the system. Components pass data through the chipset, and the chipset monitors the data
flow and passes data to other components.
A. Motherboard: Provides sockets for microprocessor and memory chips, slots for circuit boards, and the
circuitry that enable electrical signals to travel from component to component. Most of the hardware
components inside the system unit are attached to the motherboard.
B. Power supply: Provides electrical power to the computer system.
C. Microprocessor: Processes instructions stored in main memory. Sometimes, the microprocessor is found
underneath a cooling fan to prevent it from overheating.
D. Expansion slot: Serves as a socket on the motherboard into which an expansion card maybe inserted.
E. Expansion card: Enables a computer to control peripheral devices such as the monitor and the
microphone.
F. Chipset: Controls data flow among components.
G. IDE (Integrated Drive Electronics) cable: Transfers data from storage devices to the motherboard.
H. Disk drives: Stores data permanently (even after the computer is turned off). They include the floppy
disk drive, the CD-ROM (compact disk read-only-memory) drive, and the hard disk drive.
2.1 Processor and Memory
2.1.1 Processor Basics
Learning Goal: Obtain general knowledge of how a microprocessor works in a computer and become
familiar with different types of microprocessors. Gain more knowledge about microprocessor performance
and about tools called "benchmarks" that are used to compare the performance of different
microprocessors.
Processor
A computer's processor is usually referred to as the microprocessor due to its size, which is about the size
of your fingernail.
A microprocessor processes all the instructions given to the computer (for example, add two numbers,
execute program instructions, or print documents). Physically, the microprocessor is a single chip known
as an integrated circuit (IC). Each chip is made out of silicon and it contains millions of transistors packed
onto a chip.
The Intel Pentium M Processor, introduced on March 12, 2003, has 77 million transistors, and the width of
the smallest wire on the chip is 0.13 micron, or 0.00000013 meter. As a reference, 0.13 micron is about
1/800 of the width of a human hair.
The microprocessor is referred to as the Central Processing Unit (CPU). The job of a microprocessor is to
execute a series of machine instructions. These instructions are procedures to carry out a task written in a
form that the computer can understand.
Instruction Execution with the CPU
Instructions are stored in the computer's memory, RAM (random access memory).
There are two main components of the CPU. One is the control unit, which accesses instructions stored in
RAM, interprets what they mean, and then dispatches them. The other is the Arithmetic/Logic Unit (ALU)
that performs arithmetic (i.e. addition, subtraction, multiplication, division) and logic (i.e. greater than, less
than, equal to) operations needed to process the instructions.
There are four steps that the CPU performs when executing an instruction; they are called the
fetch-execute cycle. The four steps are as follows:
1. Fetch- The control unit gets the instruction from memory.
2. Interpret- The control unit decodes what the instruction means and directs the necessary data to be
moved from memory to the ALU.
3. Execute- The control unit directs the ALU to perform the necessary arithmetic or logic operations.
4. Store- The result of the computation is stored in memory.
The diagram below illustrates the steps taken by the CPU to execute an instruction that adds two numbers.
The instruction is: Let R = X + Y.
Another component of the microprocessor is the cache, a special high-speed memory that stores most
recently used data in order to speed up the process of instruction execution.
Performance: Factors and Measures
The rate at which instructions are processed is controlled by an internal clock, also known as the system
clock. The internal clock sends pulses at a fixed rate to synchronize all computer operations. The unit of
measure for cycles per second is the hertz (Hz). Computer clock cycles are closely related to the execution
of instructions. So, a 3 GHz Pentium 4 machine can execute more instructions per second than a 2 GHz
Pentium 4 machine.
Instructions can differ a great deal. Some complex instructions require a lot of cycles and take a
comparatively long time to execute. Other instructions may be very simple and execute in very little time.
Sometimes machines are compared on the number of instructions per second (IPS) rather than on raw
clock speed.
Another measure of computer performance is its bandwidth, the volume of data that can be transmitted
within a fixed amount of time between components in a computer system (such as the transfer speed from
the disk to the motherboard) or through connections to other computers. Bandwidth is expressed in bits per
second (bps), or sometimes bytes per second (Bps) (recall that 8 bits equals 1 byte).
Different machines, however, should be compared by executing a standard suite of instructions with
execution times carefully measured and recorded. This is a more careful way to measure machine
performance, and it is known as benchmarking.
Types of Processors
Intel is a well-known microprocessor vendor. Microprocessors produced by Intel became popular with the
highly successful IBM Personal Computer (PC), introduced in 1981.
Companies such as Advanced Micro Devices (AMD) now market processor chips that are compatible with
the Pentium family.
Another widely-used processor architecture is the PowerPC used in the Macintosh family of computers.
The PowerPC was based on IBM's architecture and then modified by Motorola and Apple. Database
servers storing large amounts of data are sometimes built around the SPARC family of processors
developed by Sun Microsystems. On the smaller side, there are many specialized processor chip families
created for embedded applications, such as automobiles or cellular phones.
2.1.2 Post-Course Reading
Parsons/Oja, Section 2B
Learning Goal: Knowledge of the central processing unit (also "CPU" or just "processor") and different
types of computer memory
Parsons/Oja, Tech Talk: "How a Microprocessor Executes Instructions" in Chapter 2
Learning Goal: Knowledge of how microprocessors work. This reading introduces a simple
microprocessor architecture with an accumulator, some registers (R1 and R2), and some RAM (memory
locations M1 through M7). The memory is used to store both program instructions and the data the
program will operate on.
2.1.3 Types of Memory
Learning Goal: Knowledge of different types of memory used in a computer
Memory components include the main memory, also known as RAM, and the memory components needed
to boot or start a computer, ROM and CMOS.
RAM
RAM (random access memory) is a temporary holding area for both data and instructions. It is also
referred to as main memory. RAM stores data and instructions needed to execute programs. The data in
RAM is lost when the computer is turned off.
In contrast to accessing data serially, searching sequentially for the data to be retrieved, data in RAM can
be accessed directly via its address. Therefore, RAM stands for "random access memory." Random access
is similar to accessing a song on a CD directly via its track number, as opposed to finding a song serially
on tape.
RAM is measured by its memory capacity and latency.
Two major categories of RAM called DRAM and SRAM are discussed below.
DRAM - Dynamic RAM is a common type of RAM. It is made of an integrated circuit (IC), composed of
millions of transistors and capacitors. A capacitor can hold electrons, just as a cup can hold water. An
empty capacitor represents a zero, and a non-empty capacitor represents a one. The transistor is like a
switch that controls whether the capacitor's state (charged or not charged, 1 or 0) is to be read or changed.
Changing the state of a capacitor is like writing new data to a memory cell. However, a capacitor is like a
cup that leaks, in order to keep its charge, the memory control needs to be recharged or refreshed
periodically. Therefore, it is called the dynamic RAM because its state is not constant. Refreshing
capacitors also takes time and slows down memory.
SRAM - Static RAM is a type of RAM that uses transistors to store data. Because SRAM does not use
capacitors, reading data from SRAM does not require recharging the capacitors. Therefore, it is faster than
DRAM. But, because it consists of more electronic parts, it holds fewer bits and costs more compared to
DRAM of the same size. SRAM is appropriate for use in the cache because it is fast and cache does not
require a large memory capacity.
ROM
Read-only memory (ROM) is programmed with data hard-wired when it is manufactured. Data and
instructions on a ROM are permanent, or nonvolatile.
Why is ROM needed when RAM enables all the memory operations necessary for a computer? Because
data in RAM is lost when the computer is turned off, some instructions are needed for the CPU to start or
boot the computer when the computer is first turned on.
Currently, a type of ROM, electrically erasable programmable read-only memory (EEPROM), can be
updated by applying an electrical field changing instructions stored on the chip one byte at a time.
An alternative to EEPROM is flash memory. Flash memory is a type of EEPROM that rewrites data in
chunks, usually 512 bytes in size, instead of 1 bit at a time.
CMOS Memory
Configuration settings of a computer such as storage capacity, memory capacity (RAM), and display
configurations also need to be stored permanently. This information is stored in CMOS (complementary
metal oxide semiconductor) memory. The CMOS chip requires very little electrical power to hold data. It
can be powered by a small battery on the motherboard, or packaged with the chip.
2.2 Peripherals
2.2.1 Connecting Peripherals
Learning Goal: Knowledge of how components such as expansion slots, expansion cards, and types of
connectors and ports used to transfer data between peripherals and the computer system
An expansion slot is a slit-like socket on the motherboard into which a circuit board can be inserted. The
circuit board is called the expansion card; it is used to extend the capability of a computer. Examples of an
expansion card include the sound card and the video card.
An expansion card also provides port(s), which are connector(s) between the expansion card and the
peripheral device.
See the diagram below for how peripheral devices and their connectors attach to other components in a
computer.
Expansion Slots and Cards
An expansion slot is a socket on the motherboard where expansion cards can be plugged into. An
expansion card, also referred to as "expansion boards," "controller cards," or "adapters," is a small circuit
board that enhances the functionality of a computer by enabling a computer to control storage devices,
input devices, or output devices. Examples of expansion cards include graphics cards (or video cards) and
sound cards.
The image below shows an expansion card being inserted into an expansion slot.
The two most common types of expansion slots are Peripheral Component Interconnect (PCI) and
Accelerated Graphics Port (AGP). A PCI slot can hold a variety of expansion cards such as a sound card or
an Ethernet card (discussed later in this section).An AGP slot is primarily used for graphics cards (see
discussion on graphics cards below).
In laptops, a PCMCIA (personal computer memory card international association) slot, which is relatively
smaller than a PCI slot, fulfills the role of a PCI slot. Typically, a notebook computer is equipped with
PCMCIA slots for expansion cards also called CardBus cards or PC cards.
Some commonly used expansion cards are:
Graphics card- transforms images into analog data that we perceive as light when displayed on the
computer monitor.
Sound card- allows a computer to play sounds such as music from CDs, sound files, games, or DVDs. It
can also record sounds from a microphone, cassette player, or CD player.
Modem- one type of modem is the dial-up modem, which enables a computer to exchange information
with a remote computer through ordinary telephone lines.
Ethernet card- serves as the interface to a Local Area Network (LAN) at a rate of 10 Mb/s, 100 Mb/s or 1
Gb/s (1000 Mb/s).
Ports
An expansion card usually includes ports, which are connectors that enable signals to be passed in and out
of a computer or peripheral device to exploit the functionality of the expansion card. The image below
shows the ports on the back of a computer.
USB and FireWire
Universal Serial Bus (USB) ports now appear on desktop systems and laptops. Up to 127 devices can be
connected to the system unit via a USB hub, which provides multiple USB ports. These devices include
mouse, keyboard, scanner, printer, digital camera, and hard disk drive. One of the most convenient features
of a USB port is its support for "hot connectivity," which allows peripherals to be connected to the system,
configured, and used without restarting the machine.
Compared to USB, FireWire has a faster data transfer rate, and it supports up to 63 devices. It also
supports "hot connectivity." However, it is relatively more expensive than USB.
Comparing Different Ports
Below is a chart listing the relative price, usage, and status of ports. The ports are listed from fastest to
slowest data transfer rate.
Port
Usage
Status
FireWire
Camcorder and external mass storage
(e.g. CD-ROM, hard drive, etc.)
Becoming the standard for digital video devices
USB
Most devices
Becoming the standard for most peripheral devices
Parallel
Printer
Becoming obsolete
Serial
Modem
Becoming obsolete
PS/2
Keyboard, mouse
Becoming obsolete
2.2.2 Post-Course Reading
Parsons/Oja, 5th and 6th editions: Subsection "Expansion Slots, Cards, and Ports" or 7th edition:
Section 2D
Learning Goal: More in-depth knowledge of expansion slots, cards, and ports in a computer system
2.2.3 Buses
Learning Goal: Familiarity with types of bus standards used to transfer data within a computer
Information transfers to and from the CPU go through some type of bus. The illustration below indicates
how the physical bus lines are connected to components inside a system unit.
A bus is a pathway through which data is transferred from one part of a computer to another. It consists of
the data bus and the address bus. Every bus has a width, a speed, and a transfer rate. The tables below lists
various buses named according to the device that the data passes through.
Bus Type
Front side
RDRAM
DRAM
PCI
AGP
Width (in bits)
64
16
64
32-64
32
Speed (MHz)
66-200
533
66-200
33-66
66-528
X-pumped
1-4
2
1-2
N/A
N/A
Y-channeled
N/A
1-2
N/A
N/A
Distance from chipset
<0.1m
<0.1m
<1m
<1m
Peak transfer rate
528MBps6.4GBps
2.1-4.3
GBps
132-528
MBps
264MBps
-2.1GBps
528MBps-6.4
GBps)
Bus Type
IDE
USB
FireWire
Width (in bits)
8
1
1
Speed (MHz)
33-133
variable
variable
X-pumped
N/A
N/A
N/A
Y-channeled
1-2
N/A
N/A
Distance from chipset
<1m
<10m
<10m
Peak transfer rate (MBps)
33-266MBps
1.5-60
50-100
2.2.4 Input/Output Devices
Learning Goal: Knowledge of various types of input and output devices
Input Devices
1. Cameras
2. Digital Camcorders
3. Scanners
Output Devices: Monitors and Projectors
1. CRT Monitors
2. LCD Monitors
3. Projectors
Output Devices: Printers
1. Ink Printers
2. Dye-Sublimation Printers
3. Laser Printers
2.2.5 Post-Course Reading
Parsons/Oja, Subsections "Installing Peripheral Devices," "Display Devices," and "Printers" in Section 2D
Learning Goal: Knowledge of the different types of printers and monitors available
Parsons/Oja, Sections 7A-D
Learning Goal: Knowledge of how visual and audio digital equipments work
Optional:
7th edition: Parsons/Oja, Computers in Context: "Astronomy" in Chapter 12
2.3 Storage Devices
2.3.1 Pre-Course Reading
Parsons/Oja, Section 2C
Learning Goal: Knowledge of the variety of storage media, magnetic and optical, used by modern
computers
2.3.2 Disk Controller Interfaces
Learning Goal: Knowledge of the IDE (Integrated Drive Electronics) interface used for connecting disks
to PC-based computer systems (The disk controller is responsible for the physical operation of the drive
mechanism and the transfer of bytes between the drive and main memory)
We have discussed Universal Serial Bus (USB) and FireWire. An IDE (Integrated Drive Electronics) is the
interface that enables data to transfer between storage devices and the chipset. IDE is designed specifically
as disk interface whereas USB and FireWire can interface with other devices besides storage devices such
as digital cameras and printers.
Below is a diagram illustrating the disk controller, the IDE interface, and the storage devices with respect
to other components in a computer system. Note that the functionality of the disk controller is often
integrated into the chipset.
2.3.3 Mass Storage
Learning Goal: Knowledge of numbering systems used to represent data in computing
How Mass Storage Devices Differ from RAM
Mass storage devices (magnetic disks, optical disks, and magnetic tape) have slow access times and low
transfer rates. But, mass storage technologies also have several important advantages:
1. They are nonvolatile—meaning that information is not lost when power is turned off.
2. They have huge capacities, measured in billions or even trillions of bytes.
3. Their cost per bit stored is far lower than RAM.
4. In some cases, they use removable media that can be popped into a drive, used as needed, and then
taken out of the drive, or mailed to a friend.
Disk Drive Reliability
The read/write head is very, very close to the disk surface. If a head encounters a dust particle sitting on
the surface of a disk while the disk is spinning at several thousand rpm, the head will crash into the disk,
damaging itself and the magnetic coating on the disk.
A common specification for disk drive reliability is mean time between failures (MTBF). Typically, disk
drives for PCs have MTBF ratings of about 500,000 hours, 57 years. However, MTBF is a theoretical
estimate. The MTBF rating should be used in conjunction with service life. Service life is the amount of
time before failures occur due to increased wear and tear of the component devices.
Optical Media: CDs versus DVDs
Data in an optical media is read and written using laser beams. Compact discs (CDs) and digital video
discs (DVDs) are optical disks. A DVD is an enhanced form of a CD. The two types of disks are
physically the same size, but they differ in format. DVDs offer much greater capacity, which they achieve
in two ways. First, DVDs have narrower tracks, so they can squeeze more tracks onto the same size disk.
The second way that DVDs achieve increased capacity over CDs is by using multiple layers of tracks.
Magnetic Media
Magnetic media range from some of the smallest capacity storage devices, floppy disks, to the largest
capacity devices, hard disk drives.
Smaller portable drives are being manufactured with larger capacities. For example, Iomega's Mini USB
storage device offers 64MB, 128MB, or 256MB of storage capacity on a storage device the size of a car
key. Another portable storage device offered by Iomega is the pocket-size HDD Desktop external hard
drive. It is available in 40GB, 80GB, or 120GB of storage capacity. Both devices can be connected to a
USB or FireWire port.
Fixed (non-removable) hard disk drives are still the main storage medium for computers today. They can
hold more data than any of the removable media types, optical or magnetic. On most personal machines,
the operating system, application programs, and user data all reside on one hard drive. Hard drives run
from 20 GB up to around 300 GB, with the limit continuing steadily upward each year. Another important
characteristic when comparing hard disk drives is the speed at which a disk drive rotates. Slower drives
spin at 4200 rpm (i.e. laptop computers); faster ones, at 15,000 rpm.
Optical versus Magnetic
Optical media are more durable. They are not ruined by dust or moisture, nor are they vulnerable to
electrical damage (however, they can be damaged by physical damages such as scratches). Optical media's
MTBF rating (average life expectancy) ranges between 30 and 300 years, while magnetic media utilize
magnetic properties that have a MTBF of about 3–7 years. Optical media are also less expensive per MB
than magnetic disks. On the other hand, magnetic disks, with the exception of floppy disks, can be written
and read faster than optical disks. Finally, most hard disk drives offer greater capacity than any currently
available optical device.
Solid State
A popular type of portable storage for small devices is flash memory. Examples of flash-memory storage
devices are CompactFlash and SmartMedia cards.
Comparing Storages
Name
Type
Capacity
Writability
High-density floppy disk
Magnetic
1.44 MB
Unlimited
SmartMedia card
Solid state
2 - 256 MB
Many
CompactFlash card
Solid state
4 MB - 4 GB
Many
Super floppy
Magnetic
120 or 240 MB
Unlimited
USB storage device
Solid state
64, 128, 256 MB, or more
Many
CompactFlash form factor—Microdrive
Magnetic
340 MB, 1 GB, 4 GB
Unlimited
Iomega Zip disk
Magnetic
100, 250, or 750 MB
Unlimited
CD-ROM
Optical
650 or 700 MB
Read only
CD-R
Optical
650 or 700 MB
Write once
CD-RW
Optical
650 or 700 MB
Many
Iomega Jaz disk
Magnetic
1 or 2 GB
Unlimited
DVD-R
Optical
4.7 GB
Write once
DVD-RW
Optical
4.7 GB
Many
DVD-ROM (SLSS)
Optical
4.7 GB
Read only
DVD-ROM (DLSS or SLDS)
Optical
9.4 GB
Read only
DVD-ROM (DLDS)
Optical
18.8 GB
Read only
Hard disk drive
Magnetic
20 GB and up
Unlimited
HDD Desktop external hard drive
Magnetic
20, 30, 40 GB, or more
Unlimited
2.4 Putting Together the Hardware Components
2.4.1 How Components Work Together
Learning Goal: Knowledge of how components introduced in this unit work with one another to enable a
computer to function
The CPU executes instructions stored in memory devices. When the computer is being booted, the CPU
fetches instructions from the permanent memory devices, ROM and CMOS. ROM is read-only memory
that stores instructions needed to start up the computer. CMOS contains system configuration data. Once
the computer is booted, RAM is used to load the rest of the instructions to be executed by the CPU. Data
in RAM is temporary and will be lost when the computer is turned off.
Data from storage devices such as the CD-ROM drive and the hard drive are passed through the disk
controller. Data can also be stored on hard disk or CD.
Data in the hardware system passes through buses. The buses are the communication channels among
components in the system unit.
Peripheral devices such as the keyboard, mouse, joystick, printer, speakers, microphone, etc. are connected
to the computer via ports typically in the back of a system unit. Graphics cards or sound cards are also
examples of expansion cards that can be plugged into the expansion slot of the computer to extend or
enhance the functionality of a computer.
When a computer processes requests from the user, the CPU directs the other components to carry out
specific tasks, and data is passed among components through buses and the chipset. Use the diagram
above as you follow through how data is transferred from component to component in the sample
scenarios provided below:
To save a file to hard disk, the CPU would pass the data to be saved through the front bus to the chipset.
The chipset sends the file data via the PCI bus to the disk controller, which would then send the data to the
hard disk storage device.
To open and display an image file, the CPU would signal the disk controller to fetch the image file on the
storage device and store it in RAM. The graphics card would then access the image data and display the
image as pixels on the computer monitor.
These are generalizations for how components interact. When trying to understand a hardware system,
keep in mind the general concepts of how components work together, and investigate the specifications of
components to gain more precise understanding of how a given hardware system works. The exact nature
of how each component works and interacts with other components is beyond the scope of this course.
2.4.2 Lab: Researching a Computer System
Learning Goal: Knowledge of how to use the Web to research a specific type of computer system by
searching for product reviews
1. Go to the Ziff Davis Web site (www.zdnet.com), and click "Reviews." Then click "Notebooks" and
select a notebook machine that looks interesting. Next, click the machine's link to call up the review
overview.
2. Now click the "Review" tab to read a detailed discussion of the product. Click "Latest Prices" to see
pricing and availability information.
3. Ziff-Davis also publishes the magazine Computer Shopper and its companion Web site
www.zdnet.com/computershopper.
4. You can also find product reviews and pricing info at the CNET Web site www.cnet.com.
2.4.3 Lab: Online Configuration
Learning Goal: Knowledge of how to use the Web to research and price the computer configurations you
are considering purchasing
1. Visit the site of a computer vendor. Assume that you have a budget of $1,200 and put together the
specification for a computer that is appropriate for a college student studying Computer Science.
2. Now assume you're buying a notebook computer for a businessperson who is a frequent airline traveler
and is concerned about weight and battery life. What can you get for $2,500?
2.5 Improving Computer Performance
2.5.1 Moore's Law
Learning Goal: Knowledge of the basis for the exponential growth in the computer's memory storage and
computational abilities
Gordon Moore, one of the founders of Intel, observed that in 1965, microchip capacity (the number of
transistors contained within a silicon wafer) had doubled every year. This trend in computing has become
known as Moore's Law. The law might be stated this way: the number of transistors that can be put on a
microchip will double every 12-18 months, until physical limitations are reached.
Below is a graph illustrating the exponential increase in the number of transistors on processors introduced
over the years.
Below is the log scaled graph to provide you with a different perspective of the exponential growth of
transistors on a microchip.
With the exponential growth of transistor density on microchips, many inferences can be made that allow
analysts to predict other developments in the computer industry. Extending the scope of Moore's Law, the
following predictions can be made:
1. Processing power (speed) doubles every 12-18 months.
2. Storage capacity of RAM doubles every 12-18 months.
Other observations are that storage capacity of hard disk drives is also increasing exponentially, and the
cost for consumers to purchase computer parts is decreasing over time.
Despite the growth in processing speed and storage capacity, the cost per byte of data processed or stored
decreases as lower-capacity memory chips become out-dated.
2.5.2 Bottlenecks
Learning Goal: An understanding of performance bottlenecks and how to correct them
Bottlenecks—Slowing a Process
A bottleneck is a step that takes a long time to complete, and thus reduces overall performance. It does not
pay to get a tremendously fast processor, if the memory is slow in letting information flow in and out. In
just the same way, a slow disk will impede overall system performance. If other parts of your computer are
too slow, buying a faster processor may not speed things up at all!
Typical Bottlenecks
The following are some areas of the hardware system that may contain a bottleneck:
1. Cache
2. RAM
3. I/O
4. Video card (particularly for 3-D gaming)
Eliminating Bottlenecks
Can we speed up a computer? Actually it isn't usually the computer that you want to speed up, but the
tasks it performs. This is an important distinction. Speeding up the computer suggests buying a faster
processor, installing faster memory, getting a faster bus, or installing faster disk drives and video
controllers. Improving your hardware for the purpose of speeding up your system will work, if you keep
the system uniformly balanced.
The key to making effective improvements is to understand why certain tasks take so long. Often, you can
do some simple experiments to see whether or not a certain item is the bottleneck. This idea is applied in a
very straightforward way by software developers, who use profiling tools to measure how long various
sections of their programs take. That way they can identify the bottlenecks and most time-consuming steps,
and focus their attention on improving those portions of the code.
2.5.3 Post-Course Reading
Parsons/Oja, Tech Talk: "Data Compression" in Chapter 7
Learning Goal: An understanding of how data compression can be used 1) to reduce the amount of space
required to store files and 2) to improve throughput by reducing the number of bytes that must be
transmitted