r Information Interchange (ASCII) specifies that each character of the alphabet requires seven bits of information with an eighth parity bit as insurance that the information has not been garbled. To an IBM mic
rocomputer the binary combination of 10000010 represents the letter a. This 8-bit unit of information is known as a byte.
The original IBM PC contains an Intel 8088 microprocessor, a microcomputer chip that se
rves as the central processing unit (CPU), or brains, of the computer. This particular chip can process 16 bits (2 bytes) of information at one time. The CPU has a clock speed of 4.77 megahertz (MHz). This mean
s that the microprocessor produces 4.77 million pulses each second. It schedules its work based on these pulses. Some microprocessors have faster clock speeds and thus can perform tasks such as mathematical ope
rations faster. The IBM AT (Advanced Technology), for example, uses an Intel 80286 microprocessor and has a clock speed of 8.0 MHz. The IBM PS/2 Model 80 uses a 32-bit Intel 80386 microprocessor and has a clock
speed that can reach 25 MHz. The next generation Intel 80486 microprocessors are already approaching a speed of 50 MHz. Since a local area network generally will use its fastest, most powerful computer to serv
ice network workstations, clock speed becomes a significant factor in a local area network's overall efficiency. In addition to performing routine mathematical operations, a PC's CPU also processes information
that comes to it from a variety of sources, including the keyboard. It needs a workspace in which to store some of its calculations temporarily, a need it satisfies by using some of the computer's memory.
LAN networks / RAM & ROM
Computers
Conclusion
Configurations
Connect
Connecting
Considered
Contain
Contains
Corporation
Could
Critical
Current
Cushion
Database
Define
Depend
Depending
Designed
Diagnose
Different
Digits
Diminishing
Discover
Disks
Display
Displayed
Displaying
Displays
Distance
Distributed
Dozen
Drive
Drives
Efficiency
Efficiently
Heads
Hercules
Ibm's
Ideal
Including
Information
Insurance
Intel
Interchange
Interfaces
Keyboard
Kilobytes
Knowledge
Known
Letter
Local
Located
Management
Mathematical
Means
Measured
Megahertz
Memory
Microcomputer
Microcomputers
Microprocessor
Microprocessors
Million
Model
Number
Offer
Offered
Operations
Original
Overall
Parity
Particular
Perform
Performing
Permanent
Picture
Pixels
Powerful
Process
Processes
Processing
Produces
Program
Programs
Properly
Provides
Pulses
Random
Random-access
Reach
Read-only
Refer
Represents
Require
Requires
Resolution
Retains
Routine
Through
day's
Total
Track
Travels
Turned
Types
Unlike
Unlit
Users
Using
Usually
Varies
Variety
Vertical
Vertically
Video
Whether
Which
While
White
Wished
Without
Working
Workspace
Workstations
Pro 1.0F!
Pro 1.0I
Main Dictionary
User Dictionary
ImpulseCMdt
Main
Impulse
Calculations
Capable
Cards
Central
Certain
Chapter
Character
Characters
Circuit
Clock
Close
Coated
Color
Colors
Colors/screen
Combination
Comes
Communication
Companies
Compared
Components
Computer
Computer's
Satisfies
Schedules
Screen
Screens
Sealed
Second
Selected
Sends
Separates
Serious
Serve
Serves
Service
Seven
Several
Share
Shortage
Signal
Signals
Significant
Simultaneously
Since
Single
Sixteen
Sixty-four
Store
Stores
System
Tasks
Technology
Temporarily
Temporary
Their
There
These
Though
Thousands
There are two types of memory associated with microcomputers
random- access memory (RAM) and read-only memory (ROM). ROM is permanent memory that retains information even when the computer is turned off. Microc
omputers store their most critical programs in this area, including a program to diagnose the computer when it is turned on to ensure that all components are working properly. A computer also stores its bootstr
ap program in ROM, the program that provides the computer with enough knowledge to load information from a disk.
Unlike ROM, random-access memory (RAM) is temporary memory that retains information only while t
he computer is on. It is measured in kilobytes (thousands of bytes of storage). The original IBM generally came standard with 256K (256 kilobytes) of RAM on its system board ("motherboard"), but it could be expEhanded to 640K by adding a memory circuit card to one of the expansion slots located on the motherboard.
A"LAN Networks / Monitors & Adaptors
Board
Bootstrap
Brains
Brand
Broadest
Built-in
Bytes
Cable
Cabling
Unlike today's second generation of IBM microcomputers, which have built-in video interfaces, the original IBM PC uses one of its expansion slots for a video adapter, a circuit card that sends video signals to
a monochrome or color computer monitor. A monochrome monitor displays one color in addition to black, and generally amber, green, and white are the types of monochrome monitors used with an IBM PC. Because of i
ts high resolution, a monochrome monitor is ideal for word processing, spreadsheet analysis, and database management, all tasks that do not require color. A monitor's screen contains a number of small blocklike
picture elements (pixels) that are either lit or unlit to form characters. The number of pixels that can be displayed horizontally and vertically is a function of both the monitor and its video adapter card. F
or the original IBM PC, IBM offered the Monochrome Display Adapter, which could display 720 horizontal pixels X 350 vertical pixels. This is still considered to be very high resolution.
A monochrome monitor re
quires a monochrome adapter card in one of the PC's expansion slots and a cable connecting the card to the monitor. Many computer users with monochrome monitors want to see graphs displayed on their screens, wh
ich is possible only if the monochrome adapter card can also display graphics. Although IBM's own monochrome adapter card does not permit graphics to be displayed, several companies offer video adapters such as
the Hercules Monochrome Graphics Card (from Hercules Technology) that can display graphics without diminishing resolution.
Users of the original IBM PC who wished to display color graphics usually selected a
color graphics adapter (CGA) or an enhanced graphics adapter (EGA) along with a monitor capable of displaying the appropriate level of resolution. CGA cards, for example, provide a monitor with 640 X 200 resolu
tion and can also display sixteen colors, though only four simultaneously. EGA cards, on the other hand, provide 640 X 350 resolution and can display sixty-four colors, sixteen of which can be displayed at any
given time. Table 1-1 summarizes the different standards for monochrome, CGA, and EGA cards and the standards associated with IBM's second generation of microcomputers.
Standard Resolution Pixels Total Colo
rs Colors/Screen
Hercules MDA 720 x 348 N/A N/A
CGA 640 x 200 16 4
EGA 640 x 350 64 16
PGA 640 x 480 4096
256
CGA Mode 640 x 200 4096 256
Text Mode 640 x 480 16 2
CGA Mode 640 x 200 4096 256
Text Mode 720 x 400 16 2
st programs require a user to indicate specifically which type of video adapter card will be used so that the program will send the proper signal to the card. As you will discover later in this book, this can pO
resent some problems when a program is used on a local area network, since different workstations may contain different video adapter cards.
Bytes
Disks
Local
Monitors
Network
Networks
10000010
32-bit
8-bit
80286
80386
80486
AboutAddition
Advanced
Along
Alphabet
Already
Although
Monitor
Monitor's
Monitors
Monochrome
Motherboard
Needs
Network
Network's
Networks
Ninety
Amber
American
Analysis
Anywhere
Approaching
Appropriate
Approximately
Arranged
Ascii
Associated
Available
Based
Because
Become
Becomes
Between
Binary
Black
Blocklike
Board
Offered
Operation
Operations
Organization
Original
Other
Overall
Oxide
Parity
Particular
Permanent
Permit
Permits
Personal
Phonograph
Physical
Picture
Pixels
Place
Platter
Possible
Powerful
Present
Problems
Process
Processes
Processing
Produces
Program
Programs
Proper
Properly
Holding
Horizontal
Horizontally
Ibm's
Ideal
Illustrates
Including
Indicate
Information
Insurance
Intel
Interchange
Interfaces
Keyboard
Kilobytes
Knowledge
Known
Later
Learn
Letter
Level
Loading
Local
Locate
Located
Looks
Magnetic
Management
Material
Mathematical
Eighth
Either
Elements
Enhanced
Enough
Ensure
Environment
Examine
Example
Expanded
Expansion
Extent
Faced
Factor
Faster
Fastest
Figure
Files
First
Floppy
Flowing
Function
Garbled
Generally
Generation
Given
Gradually
Graphics
Graphs
Great
Green
Provide
Provides
Pulses
Random
Random-access
Rapidly
Rather
Reach
Read-only
Read/write
Record
Refer
Relatively
Represents
Require
Requires
Resolution
Resources
Retains
Return
Revolutions
Rigid
Routine
Slots
Small
Software
Sophisticated
fically
Specifies
Speed
Speeds
Spreadsheet
Standard
Standards
Still
Storage
Store
Stores
Straight
Subject
Summarizes
Surface
Survey
System
Table
Taken
Tasks
Technology
Temporarily
Temporary
Their
There
These
Thirty
Though
Thousands
Means
Measured
Media
Megabytes
Megahertz
Memory
Metal
Microcomputer
Microcomputers
Microprocessor
Microprocessors
Might
Million
Millionth
Milliseconds
Minute
Model
LAN Networks / Hard disks
A user can work faster and more efficiently by loading all programs and data files onto one hard disk drive. Rather than using several dozen "floppy" disks, he or she can place all information on a single hard
disk drive unit capable of holding anywhere from 10 megabytes (10 million bytes) to several hundred megabytes of information. As Figure 1-4 illustrates, a hard disk is actually a rigid platter coated with a met
al oxide material that looks very much like a phonograph record. In the sealed hard disk unit, the read/write head travels rapidly (about 3600 revolutions per minute) on a very thin cushion of air that separate
s it from the magnetic surface of the hard disk. The distance between the read/write heads and the magnetic surface of the hard disk varies from 1 millionth of an inch to 1/2 millionth of an inch depending on t
he brand of hard disk. It might take approximately thirty milliseconds for the hard disk to locate and load a file compared to ninety milliseconds with a floppy disk drive. You will learn in the next chapter hoF]w hard disk drives can serve several different personal computers in a network environment.
A,LAN Networks / What is a Local area Network?
About
Access
Accounting
Actual
Actually
Adapter
Adapters
Adding
Addition
Advanced
Allowed
Along
Alphabet
Already
Although
Hundred
Ibm's
Ideal
Illustrates
Including
Indicate
Industry
Information
Insurance
Intel
Interchange
Interfaces
Keyboard
Kilobytes
Knowledge
Known
Let's
Letter
Level
Limited
Loading
Local
Locate
Located
Looks
Magnetic
Management
Material
Mathematical
Let's define a local area network in the broadest way possible. It is a communication network used by a single organization over a limited distance that permits users to share information and resources. The ne
xt chapter will survey the different physical configurations possible for a LAN. Whether PCs are arranged in the form of a star, a ring, or even a straight line, the speed of the network will depend to a great
extent on the type of media used to connect all units together. The next chapter will return to this subject and examine the different types of cabling available for LANs.
Distributed processing taken to its l
ogical conclusion means the linking together of microcomputers to share information and peripherals. The first local area networks were relatively primitive and were faced with a serious shortage of software de
signed for more than one user. At best, these first LANs usedfile locking, which allowed only one user at a time to use a certain program. Gradually, though, the software industry has become more sophisticated.
Today local area networks can use sophisticated accounting and productivity programs that permit several users to work with the same programs at the same time (record locking). Let's take a close look at an acGAtual local area network in operation at the Widget Corporation.
Today
Today's
Together
Total
Track
Travels
Turned
Types
Units
Unlike
Unlit
Usedfile
Users
Using
Usually
Varies
Variety
Vertical
Vertically
Video
Whether
Which
While
White
Widget
Wished
Workspace
Workstations
Perform
Performing
Peripherals
Permanent
Permit
Permits
Personal
Phonograph
Physical
Picture
Pixels
Place
Platter
Possible
Powerful
Present
Primitive
Problems
Process
Processes
Processing
Produces
Productivity
Program
Programs
Proper
Properly
Later
Learn
Let's
Letter
Level
Limited
Linking
Loading
Local
Locate
Located
Locking
Logical
Looks
Magnetic
Management
Material
Mathematical
Without
Working
Workspace
Workstations
Sources
Specifically
Specifies
Speed
Speeds
Spreadsheet
Standard
Standards
Still
Storage
Store
Stores
Straight
Subject
Summarizes
Surface
Survey
System
Table
Taken
Tasks
Technology
Temporarily
Temporary
Their
There
These
Thirty
Though
Thousands
LAN Networks / bits & bytes
Computers can keep track of whether a wire has current flowing through it (1) or no current flowing through it (0). We refer to each of these binary digits of information as a bit. The American Standard Code fo
~~~~~~
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||||||
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zzzzzz
yyyyyy
xxxxxx
wwwwww
vvvvvv
uuuuuu
tttttt
ssssss
rrrrrr
qqqqqq
ppppppG
oooooo
nnnnnn
mmmmmm
llllll
kkkkkk
jjjjjj
iiiiii
hhhhhh
gggggg
ffffff
eeeeee
dddddd
cccccc
bbbbbb
aaaaaa
``````
______
^^^^^^
]]]]]]
\\\\\\
[[[[[[
ZZZZZZ
YYYYYY
XXXXXX
WWWWWW
VVVVVV
UUUUUU
TTTTTT
SSSSSS
RRRRRR
QQQQQQ
PPPPPP
OOOOOO
NNNNNN
MMMMMM
LLLLLL
KKKKKK
JJJJJJ
IIIIII
HHHHHH
GGGGGG
FFFFFF
EEEEEE
DDDDDD
CCCCCC
BBBBBB
AAAAAA
@@@@@@
??????
>>>>>>
======
<<<<<<
::::::
999999
888888
777777
666666
555555
444444
333333
222222
111111
000000
//////
......
------
,,,,,,
++++++
******
))))))
((((((
''''''
&&&&&&
%%%%%%
$$$$$$
######
""""""
LAN Networks
This Demonstration disk contains only 5 files.
The original Database consists of 94 subject
definitions and is fully operational.
E%Additional Database subjects include:
AdMS-DOS Commands
Hard Disk Management
Macintosh LAN
Basic LAN Management
Computer Terms & Definitions
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(.txt)