- 1. Using Management Information Systems David Kroenke Hardware
and Software Chapter 3
2. Learning Objectives
- Learn the terminology necessary to be an intelligent consumer
of hardware products.
- Know the functions and basic features of common hardware
devices.
- Understand the essentials of the representation of computer
instructions and data.
- Know the purpose of the CPU and main memory, and understand
their interaction.
3. Learning Objectives (Continued)
- Understand the key factors that affect computer
performance.
- Learn basic characteristics of the four most popular operating
systems.
- Know the sources and types of application software.
- Learn about viruses, Trojan horses, and worms and how to
prevent them.
4. Essential Hardware Terminology
- Computing devices consists of computerhardwareandsoftware.
- Hardware is electronic components and related gadgetry that
input, process, output, and store data according to instructions
encoded in computer programs or software.
- Your personal computer and other computers like it
aregeneral-purpose computers.
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- They can run different programs to perform different
functions.
5. Essential Hardware Terminology (Continued)
- Some computers arespecial-purpose computers.
-
- The programs they run are fixed permanently in memory.
-
- The computer in your cell phone is a special-purpose computer,
and so is the computer in your car that meters fuel to your cars
engine.
- The principles and fundamental components of general-purpose
and special-purpose computers are the same;
-
- The sole difference is the computer can process a variety of
different programs
6. Input, Processing, Output, and Storage Hardware
- One easy way to categorize hardware is by its primary
function:
7. Figure 3-1 Input, Process, Output, and Storage Hardware 8.
Processing Hardware
- Processing devicesinclude thecentral processing unit (CPU) ,
which is sometimes called the brain of the computer.
-
- The CPU selects instructions, processes them, performs
arithmetic and logical comparisons, and stores results of
operations in memory
- The CPU works in conjunction withmain memory.
-
- The CPU reads data and instructions from memory, and it stores
results of computations in main memory (RAM).
- Computers also can havespecial function cardsthat can be added
to the computer to augment the computers basic capabilities.
-
- A common example is a card that provides enhanced clarity and
refresh speed for the computers video display.
9. Storage Hardware
- Storage hardwaresaves data and programs.
-
- Amagnetic diskis by far the most common storage device,
althoughoptical disks , such as CDs and DVDs are popular.
-
- In large corporate data centers, data are sometimes stored
onmagnetic tape .
10. Binary Digits
- Computers represent data usingbinary digits , calledbits.
-
- A bit is either a zero or a one.
-
- Bits are used for computer data because they are easy to
represent physically.
- A computer can be designed so an openswitchrepresents zero and
a closed switch represents a one.
- Or, the orientation of amagnetic fieldcan represent a bit;
-
- Magnetism in one direction represents a zero
-
- Magnetism in the opposite direction represents aone
- Or, foroptical media , small pits are burned onto the surface
of the disk so that they will reflect light
-
- In a given spot, a reflection means a one
-
- No reflection means a zero
11. Figure 3-4 Bits Are Easy to Represent Physically 12.
Computer Instructions
- Computers use bits for two purposes:Instructions and Data
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- Instructions Add two numbers together
-
-
- The collection of instructions that a computer can process is
called thecomputers instruction set.
-
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- Microsoft Intel instruction set.
-
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- Macintosh -PowerPC instruction set
-
-
-
- In 2006, Apple began offeringMacintosh computers with a choice
of either Intel or PowerPC processors.
-
-
- Currently, you cannot run a program designed for one
instruction set on a computer having a different instruction
set.
13. Computer Data
-
-
- All computer data are represented by bits.
-
-
- The data can be numbers, characters, currency amounts, photos,
recordings, or whatever.
-
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- Bits are grouped into 8-bit chunks calledbytes.
-
-
- For character data, such as letters in a persons name, one
character will fit into one byte.
-
-
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- Thus, when you read a specification that a computing device has
100 million bytes of memory, you know that the device can hold 100
million characters.
14. Figure 3-5 Important Storage-Capacity Terminology 15.
Ambiguity of Binary Data
- It is not possible to determine the type of computer data just
by looking at the data.
-
- The bit string 01000001 can be interpreted as the decimal
number 65, as the character A, or as part of a picture or a sound
file.
-
- Further, it could be part of a computer instruction.
- The CPU determines how to interpret a bit string from the
context in which it encounters it.
-
- If the string occurs in the context of reading instructions, it
will be interpreted as a computer instruction.
-
- If it occurs during arithmetic operations, it will be
interpreted as the number 65.
16. Knowledge for the Informed Professional
- Suppose that your IS department states that you can buy three
different computer configurations for three different prices.
- The computers are described by expressions like the
following:
-
- Intel Pentium 4 Processor at 2.8 GHz with 533MHz Data Bus and
512K cache, 256MB RAM
-
- Intel Pentium 4 Processor at 2.8 GHz with 533MHz Data Bus and
512K cache, 512 MB RAM
-
- Intel Pentium 4 Processor at 3.6 GHz with 533MHz Data Bus and
1MB cache, 256 MB RAM
17. Knowledge for the Informed Professional (Continued)
- Now, you, have two choices :
-
- You can tell the people in the IS department to specify what
they think is best;
-
- Or, with a little bit of knowledge on your part, you can work
with the IS department to ask intelligent questions about the
relationship of these computers to the kind of work your department
does
18. Figure 3-6 Computer with Applications Loaded 19. CPU and
Memory Usage
- Themotherboardis a circuit board upon which the processing
components are mounted and/or connected.
- Thecentral processing unit(CPU)reads instructions and data from
main memory, and it writes data to main memory via adata
channel,orbus.
- Main memoryconsists of a set of cells, each of which holds a
byte of data or instruction.
-
- Each cell has an address, and the CPU uses the addresses to
identify particular data items.
-
- Main memory is also calledRAM memory , or justRAM.
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- RAM stands forrandom access memory.
-
-
- The termrandomis used to indicate that the computer does not
need to access memory cells in sequence; rather, they can be
referenced in any order.
20. CPU and Memory Usage (Continued)
- To store data or instructions, main memory or RAM must have
electrical power. When power is shut off, the contents of main
memory are lost.
-
- The termvolatileis used to indicate that data will be lost when
the computer is not powered.
- Magnetic and optical disks maintain their contents without
power and serve as storage devices.
-
- You can turn the computer off and back on, and the contents of
both magnetic and optical disks will be unchanged.
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- Magnetic and optical disk arenonvolatile.
21. The Contents of Memory
- Memory is used for three purposes:
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- It holds instructions of the operating system
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- It holds instructions for application programs such as Excel or
Acrobat.
- The operating system (OS) is a computer program that controls
all of the computers resources
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- It processes key strokes and mouse movements.
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- It sends signals to the display monitor.
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- It reads and writes disk files.
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- It controls the processing of other programs.
22. Memory Swapping
- Memory swappingoccurs when there is a request to the operating
system to store data in memory and the data will not fit because
there is not enough free memory to store the requested data.
-
- For this case, the operating system will have to remove or swap
something to make space.
- Smaller degrees of swapping occurs when:
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- Your computer has a very large main memory.
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- You use only one or a few programs at a time.
- You may have a serious problem if:
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- Your computer has a small memory capacity.
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- You need to use many programs or process many large data
files.
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- Solution - add more main memory!
23. Work at the CPU
- The CPU reads instructions and data from memory via the data
bus.
- The maximum speed at which it transfers data is determined by
the speed of main memory and the speed and width of the data
bus.
- A bus that is 16 bits wide can carry 16 bits at a time; one
that is 64 bits wide can carry 64 bits at a time.
- The wider the bus, the more data it can carry in a given
interval of time.
24. Work at the CPU (Continued)
- Because the data transfer rate depends on both the width of the
data bus and the speed of main memory, another way to speed up the
computer is to obtain faster memory.
- Some data are accessed more frequently than other data.
-
- Because of this, computer engineers found they could speed up
the overall throughput of the CPU by creating a small amount of
very fast memory, calledcache memory.
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- The most frequently used data are placed in the cache.
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- Typically, the CPU stores intermediate results and the most
frequently used computer instructions in the cache.
25. Figure 3-7 Picture File Overlays Memory Previously Used by
Excel 26. Work at the CPU (Continued)
- Each CPU has a clock speed that is measured in cycles per
second, or hertz.
- A fast modern computer has a clock speed of 3.0 gigahertz
(abbreviated GHz), or 3 billion cycles per second.
- In general, the faster the clock speed, the faster work will
get done.
27. Figure 3-8 Hardware Components and Computer Performance 28.
CPU and Data Bus
- A fast CPU and data bus are most useful when processing data
that already reside in main memory.
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- Once you have downloaded a large spreadsheet, a fast CPU will
rapidly perform complicated, formula-based what-if analyses.
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- A fast CPU also is useful for processing large graphics
files.
-
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- Example, manipulating the brightness of the elements of a large
picture
- If the applications that you or your employees use do not
involve millions of calculations or manipulations on data in main
memory, then buying the fastest CPU is probably not
worthwhile.
29. Main Memory
- Two key performance factors for main memory are speed and
size.
- Normally, a particular computer make and model is designed to
use a given memory type, and the speed for that type is fixed.
-
- There is nothing you can do to increase memory speed.
- You can, however, increase theamountof main memory, up to the
maximum size of memory that your computer brand and modelcan
hold.
- If your computer is constantly swapping files, installing more
memory will dramatically improve performance.
-
- Memory is cheap and is often the best way to get better
performance
30. Magnetic Disks
- Magnetic and optical disks provide long-term, nonvolatile data
storage.
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- The types and sizes of such storage devices will affect
computer performance.
- Data are recorded on magnetic disks in concentric circles.
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- The disks spin inside the disk unit, and as they spin magnetic
spots on the disks are read or written by theread/write head .
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- The time required to read data from a disk depends on two
measures:
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- Rotational delaythe time it takes the data to rotate to the
data point
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- Seek time -time it takes the read/write head arm to position
the head over the correct circle
31. Figure 3-9 Magnetic Disk Components 32. Optical Disks
- There are two kinds of optical disks: CDs (compact disks) and
DVD (digital versatile disks).
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- Both are made of plastic and coated with a photosensitive
material.
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- Bits are recorded by burning a pit into the photosensitive
material using a low-power laser.
-
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- The presence of a pit causes light to reflect and signifies a
one; the absence of reflection signifies a zero.
- Thepracticaldifferences between CDs and DVDs are capacity and
speed.
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- A typical CD has a maximum capacity of 700 MB, whereas a DVD
disk can store up to 4.7GB.
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- DVD transfer rates about 10 times faster than those for
CDs.
33. Video Displays
- There are two types of video display monitors: CRTs and
LCDs.
- CRT monitorsusecathode ray tubes , the same devices used in
traditional TV screens.
-
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- dot pitch -the distance between pixels on the screen.
-
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- The smaller the dot pitch, the sharper and brighter the screen
image will be.
- LCD monitorsuse a different technology calledliquid crystal
display.
-
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- With LCD monitors, no tube is required, so they are much
slimmer, around 2 inches or so deep.
-
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- pixel pitch- distance between pixels on the screen.
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- The smaller the pixel pitch, the sharper and brighter the image
will be.
34. Figure 3-10 Contemporary Operating Systems 35. Application
Software
- Application softwareconsists of programs that perform a
business function.
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- Some application programs are general purpose, such as Excel or
Word.
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- Other application programs are specific
-
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- QuickBooks, for example, is an application program that
provides general ledger, and other accounting functions.
- You can buy computer software several ways:
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- Off-the-shelf with alterations
36. Application Software (Continued)
- Horizontal-market application softwareprovides capabilities
common across all organizations and industries.
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- Word processor, graphics programs, spreadsheets, and all
presentation programs are all horizontal-market application
software.
- Vertical-market application softwareserves the needs of a
specific industry.
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- Examples of such programs are:
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- Those used by dental offices to schedule appointments and bill
patients
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- Those used by auto mechanics to keep track of customer data and
customers automobile repairs
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- Those used by parts warehouses to track inventory, purchases,
and sales
37. Application Software (Continued)
- Sometimes organizations developcustom application
software.
- They develop such programs themselves or hire a development
vendor.
- Custom development is difficult and risky.
- Every application program needs to be adapted to changing needs
and changing technologies .
38. Figure 3-11 Software Sources and Types 39. Firmware
- Firmwareis computer software that is installed into devices
like printers, print servers, and various types of communication
devices.
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- The software is coded just like other software, but it is
installed into special, read-only memory of the printer or other
device.
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- Users do not need to load firmware into devices memory.
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- Firmware can be changed or upgraded, but this is normally a
task for IS professionals.
40. Summary
- Computing devices consists of hardware and software.
- General-purpose computers can run multiple programs;
special-purpose computers, like those in cell phones, run only one
program that is fixed in memory.
- Hardware can be categorized according to its primary functions:
input, processing, output, and storage.
- Input hardware includes devices such as keyboards and
mice.
41. Summary (Continued)
- Processing hardware includes the CPU and main memory.
- Output devices are video displays, printers, and the like.
- Storage devices include magnetic and optical disks.
- Computers use bits to represent data.
- A bit, or binary digit, has a value of zero or one.
- Bits are used to represent computer instructions and data.
42. Summary (Continued)
- Four popular operating systems are Windows, Mac, OS, Unix, and
Linux.
- Computer software consists of the operating system and
application software.
- Software can be purchased off-the-shelf, purchased
off-the-shelf and then altered, or tailor-made.
- Types of software include horizontal, vertical, and
custom.
- Firmware is program code installed in read-only memory of
printers or communications devices.
43. Security GuideViruses, Trojan Horses, and Worms
- A virus is a computer program that replicates itself and
consumes the computers resources.
- The program code that causes unwanted activity is called
thepayload.
- There are many different virus types:
44. Virus
-
- Acomputer virusattaches itself to a program or file so it can
spread from one computer to another, leaving infections as it
travels. Much like human viruses, computer viruses can range in
severity: Some viruses cause only mildly annoying effects while
others can damage yourhardware ,softwareorfiles . Almost all
viruses are attached to anexecutable file , which means the virus
may exist on your computer but it cannot infect your computer
unless you run or open the malicious program. It is important to
note that a virus cannot be spread without a human action, (such as
running an infected program) to keep it going. People continue the
spread of a computer virus, mostly unknowingly, by sharing
infecting files or sendinge-mailswith viruses as attachments in the
e-mail.
45. Worm
- Awormis similar to a virus by its design, and is considered to
be a sub-class of a virus. Worms spread from computer to computer,
but unlike a virus, it has the capability to travel without any
help from a person. A worm takes advantage of file or information
transport features on your system, which allows it to travel
unaided. The biggest danger with a worm is its capability to
replicate itself on your system, so rather than your computer
sending out a single worm, it could send out hundreds or thousands
of copies of itself, creating a huge devastating effect. One
example would be for a worm to send a copy of itself to everyone
listed in your e-mail address book. Then, the worm replicates and
sends itself out to everyone listed in each of the receiver's
address book, and the manifest continues on down the line.Due to
the copying nature of a worm and its capability to travel across
networks the end result in most cases is that the worm consumes too
muchsystem memory(ornetworkbandwidth), causing Webservers , network
servers and individual computers to stop responding. In more recent
worm attacks such as the much-talked-about .Blaster Worm., the worm
has been designed to tunnel into your system and allow malicious
users to control your computer remotely
46. Trojan horses
- ATrojan Horseis full of as much trickery as the mythological
Trojan Horse it was named after. The Trojan Horse, at first glance
will appear to be useful software but will actually do damage once
installed or run on your computer. Those on the receiving end of a
Trojan Horse are usually tricked into opening them because they
appear to be receiving legitimate software or files from a
legitimate source. When a Trojan is activated on your computer, the
results can vary. Some Trojans are designed to be more annoying
than malicious (like changing your desktop, adding silly active
desktop icons) or they can cause serious damage by deleting files
and destroying information on your system. Trojans are also known
to create abackdooron your computer that gives malicious users
access to your system, possibly allowing confidential or personal
information to be compromised. Unlike viruses and worms, Trojans do
not reproduce by infecting other files nor do they
self-replicate.
47. Security GuideViruses, Trojan Horses, and Worms
(Continued)
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- Find and apply patches to the operating system and to
applications.
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- Never download files, programs, or attachments from unknown Web
sites.
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- Do not open attachments to emails from strangers.
-
- Do not open unexpected attachments to emails, even from known
sources.
-
- Run aretroactiveantivirus program at regular intervals, at
least once per week.
48. Key Terms and Concepts
Central processing unit (CPU) Clock speed Custom software Data
channel Dot pitch DVD-R DVD-ROM DVD-RW Firmware General-purpose
computer Gigabyte (GB) Hardware 49. Key Terms and Concepts
(Continued) Horizontal-market application Input hardware Intel
instruction set Kilobyte (K) LCD monitor License agreement Linux
Mac OS Macro virus Main memory Megabyte (MB) Memory swapping
Motherboard Nonvolatile OEM (original equipment manufacturer)
Off-the-self software Open-source community Operating system (OS)
Optimal resolution Output hardware Patch Payload Pixel 50. Key
Terms and Concepts (Continued) Pixel pitch Power PC instruction set
RAM memory Seek time Software piracy Special function cards
Special-purpose computer Storage hardware Terabyte (TB) Trojan
horse Unix Vertical-market application Virus Volatile Windows
Worm