Transcript An Overview of the PC

An Overview of the PC
PC and DOS Essentials
The Components of a PC
• 1981 - The Key Year
– The IBM PC
– The Intel 8086
– DOS
• All versions of these items
have been obsessed with
backwards compatibility ever
since!
The Operating System
DOS and Windows
• DOS, the operating system
acts as a link between
your PC hardware and
your applications
• Windows 3.x is a further
layer built on top of DOS
• Windows 95 is to a large
extent independent of
DOS
WINDOWS
DOS
HARDWARE
Storage Devices
• Floppy disks (diskettes)
– Slow but convenient
– Hold only small amounts of data (1.44 MB)
• Hard disks
– Fast
– Relatively cheap
– Hold large amounts of data
• Tape drives
– Excellent for back-ups
• CD-ROMs
– Excellent for storing data as reference material
– A convenient method for installing programs, such as Microsoft
Office
The Serial and Parallel Ports
• Parallel communication
– Faster than serial communication
– Used to connect the PC to a printer
• Serial communication
– Slower, used for connection to a modem
The CPU (Central Processing Unit)
• The CPU is responsible for all
calculations performed within the
PC
• It determines how fast the PC will
run and what systems will run
on it
• Additionally, it gets involved in
a host of other activities, such as
overseeing the transfer of data
from the hard disk into RAM
The ROM-BIOS and the CMOS-RAM
• The ROM-BIOS
– Read Only Memory - Basic Input Output
System
– Interface between DOS and the PC
hardware
• The CMOS-RAM
– Complementary Metal Oxide - Random
Access Memory
– A read/write chip
– Stores the system configuration, time and
date as well as the power-on password (if
you have set one)
PC Interrupts
• 16 hardware interrupts
• Allows items within the PC to signal to the CPU
that they require attention
• Items must not use the same interrupt line
• Use the MSD command to view interrupt usage
• When a new card is installed into a PC you must
ensure that it does not try to use an interrupt that
is already in use
DMA (Direct Memory Access)
• DMA was introduced in 1981 with the release of
the IBM PC
– VERY SLOW!
• The original PC was based on the Intel 8086 CPU,
which at the time was considered an OK sort of
chip, running at a reasonable speed
– To help out the CPU, the DMA was responsible for moving
information from the hard disk or floppy disk into memory,
thus by-passing the CPU. This increased throughput and
performance
Types of Bus Architecture
• ISA (Industry Standard Architecture)
is the original PC bus architecture,
introduced in 1981
• MCA (Microchannel Architecture)
was introduced by IBM in 1987 and
eliminated many of the ISA design
bottlenecks
• EISA (Extended Industry Standard
Architecture) was introduced in 1989
• Plug and Play is the latest solution
and allows automatic hardware
configuration
‘Plug and Play’
• Provides a mechanism for automatically
configuring any items you add to your PC
• Requires three elements to work successfully
– The operating system must be Plug and Play aware
•
Windows 3.1 is not Plug and Play aware, Windows 95 is
– The ROM-BIOS must be Plug and Play aware
– The cards themselves must be specially designed to
be Plug and Play aware
Getting HELP Within DOS
and Windows
• Help in DOS is limited
– HELP
– command /?
– HELP command
• Most Windows applications (and Windows itself)
contain tutorials, which are very useful for new
users
– As later versions of applications are released, the Help files
are often modified to give improved information concerning
tips and tricks
– Context-sensitive Help should be invoked when F1 is pressed
Directories and Files
PC and DOS Essentials
What are Directories?
• A convenient way of dividing up your
hard disk
• Each application can be kept in it’s
own directory
– The root directory is called CD\
– A single . represents the current directory
– A double .. represents the parent directory
Manipulating Directories Under DOS
• Directory commands include:
MD
CD
RD
TREE
DELTREE
DELTREE
Please take care
using DELTREE
Manipulating Directories Using the
Windows File Manager
• Run the File Manager program, by double clicking
on the File Manager program icon, located within
the Main group
The DIR Command
• Switches include:
– /w
– /p
– /s
– /?
What are Files?
• A file is a collection of information contained in a
single unit, stored on disk
• The DIR command displays a list of files
contained in the current directory (the current
directory is the directory you are in at the time)
File Naming Conventions
• There are very strict rules governing the naming of files
• A file name can be up to 8 characters, with a 3
character file extension. You cannot use spaces (produced by
pressing the spacebar) within a file
name
• File names, must not contain the following
characters:\|*?<>+
• You can use the underscore character
– This is often useful for making a file name more readable. You can
use numbers as well as letters
Internal vs External DOS Files
• External DOS files are held on the disk, and
loaded into your computers memory (RAM) only
as and when required
• Internal commands are pre-loaded in your
computers memory (RAM) when you switch
on a DOS-based computer
Creating Text Files - EDIT vs COPY CON
• COPY CON is a useful technique for creating
small text files
• Edit is useful for editing existing files or creating
large complex text files
Renaming, Deleting and
Undeleting Files
• DEL
– Deletes files
• REN
– Renames files
• UNDELETE
– Undeletes deleted files
Beware of accidental
file deletion!
Give me my
files back!
Copying and Moving Files Under DOS
• COPY
– Internal command
– Copies files
• XCOPY
– External command
– More flexible than copy
• MOVE
– External command
– Only works within a disk, not
between disks
Everything well organized!
Copying and Moving Files Using the
Windows File Manager
• Open the File Manager
• Click on the File drop-down menu
• Select the Copy or Move command
Viewing and Finding Files Within DOS
• View with the TYPE
command
• Use DIR/s to find
Viewing and Finding Files
Using the Windows File Manager
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•
•
•
Open the File Manager
Click on the File drop down menu
Select the Search command
Double click on an associated file to view the file
Associated files
Manipulating File Attributes
• Attributes
–
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Read Only
Archive
System
Hidden
• Use of ATTRIB
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–
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–
R
A
S
H
Read-only
Archive
System
Hidden
• In Windows manipulated via the File Manager
– File/Properties
Disk Fundamentals
PC and DOS Essentials
Types - Floppy Disks (Diskettes)
and Hard Disks
• Hard disks
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Non-removable
Inside your PC
Very fast
Hold large amounts of data
• Diskettes
– Removable
– Hold up to 1.44 MB
– Very slow
Setting Up a Hard Disk From Scratch
• Low level formatting
– Hard disk supplied with low level formatting
– DOS FORMAT command will not low level format a hard
disk
• Partitioning
– With FDISK
• High level formatting
– Using DOS FORMAT command
Disk Partitions
• Options include setting up:
– A single primary partition
– A single extended partition
– Multiple logical drives
• Manipulated via the DOS command FDISK
– A logical drive is anything addressed by a drive letter
– If you have a single large primary partition, it is referred to as
drive C:
– If you have an extended partition, use FDISK to split this into
one or more logical drives
– Referred to as drive D: E: F: etc.
High Level (Logical) Formatting
• Also called logical formatting
• All logical drives within hard disk partitions must
first be formatted
• Use the DOS FORMAT command
• Only drive C: needs to be a system (bootable)
disk
Diskette Formatting Considerations
• System and non-system diskettes
• Quick formatting
Non-System Disk!
?
Unformatting a Disk
• UNFORMAT
• When you format a disk, by default it saves
information concerning the disks contents
• Providing that you use the UNFORMAT command
immediately this information can be used to
restore the contents of the disk
Copying and Labelling Diskettes
• DISKCOPY
– Uses identical source and target diskettes
Speeding Up Disk Access With DEFRAG
• Removes file fragmentation
• Speeds up disk access
• Run DEFRAG if the disk appears slow
The effect can
sometimes be
dramatic
Buffers
• Used to speed up access from the disk
• Set up via the CONFIG.SYS
SmartDrive
• Setup via the AUTOEXEC.BAT
• Can increase to AND from the hard disk
Disk Compression
DBLSPACE and DRVSPACE
• Compresses data held on a disk, and increases
the storage capacity
• Is it safe?
• What about disk performance?
Before
After
Disk Structures
• Sides
• Sectors
• Tracks
• Clusters
The DOS Boot Sequence
• The boot record
• Two hidden system files
• CONFIG.SYS
• COMMAND.COM
• AUTOEXEC.BAT
RAM Disks
• You can treat part of your memory (RAM) as a virtual disk
• Accessed much faster than a real disk
• Useful with Windows, as you can create temporary files of a
virtual disk (by pointing the TEMP= variable to the virtual
disk, within the AUTOEXEC.BAT)
Memory Fundamentals
PC and DOS Essentials
Type of Memory Chips - RAM and ROM
• RAM
– Random Access Memory
– Read/write memory
– DOS and application programs are loaded into RAM
• ROM
– Read Only Memory
– Contains hard coded information that is used by the operating
system
– ROM-BIOS
– Video ROM
– Hard disk ROM
The IBM PC, the 8086 CPU and DOS
• The original IBM PC containing an
Intel 8086 CPU and DOS were all
released at the same time
• The original PC was designed
around the Intel 8086 CPU and DOS
in turn was designed to run
specifically on the 8086 CPU
• DOS has since been left behind by
the hardware, including the CPUs
It’s not
1981
anymore!
Conventional Memory
• Defined by addressing limitations of the
8086/8088 CPU
• Is the first 1 MB of memory
• Not protected
• Traditionally only 640 KB used by DOS and DOS
applications
Extended Memory
• Protected Memory above 1 MB
– Used by Windows and Windows applications
– The original CPU for which DOS was designed only had 20
address lines, and could only address a maximum of 1 MB
– In 1984, with the release of the IBM AT based on the Intel 80286 CPU,
the number of address lines was raised to 24, giving a maximum
memory address range of 16 MB
– The first 1 MB was addressed in Real Mode, while the remaining
15 MB were addressed in Protected Mode and were referred to as
Extended Memory
– 386/486-based PCs can, in theory, address 4 GB of memory
• Extended Memory Specification - (XMS)
– Defines a standard used to access Extended Memory
– DOS and Windows use a driver HIMEM.SYS to control access to
the XMS memory
Expanded Memory
An Old Technology!
• Used only by certain DOS applications
– Windows applications do not require Expanded Memory
– Used to extend the life of old 8086-based PCs (which could
only address 1 MB of Conventional Memory)
– Modern DOS programs will tend to use Extended Memory
rather than Expanded Memory
– Traditionally requires a special Expanded Memory card and a
special device driver
– Requires a 64 KB page frame in the UMBs
• May now be emulated from Extended Memory by
using the EMM386.EXE device driver
DEVICE=C:\DOS\EMM386.EXE
The Upper Memory Blocks and the
High Memory Area
• The UMB space is
located between 1 MB
640 KB and 1 MB
• The HMA is a 64 640 KB
KB area just
above 1 MB
HMA
UMBs
Conventional
Memory
0 KB
Using the UMBs and HMA
- Devicehigh and Loadhigh
• Allows you to load items with the CONFIG.SYS
and the AUTOEXEC.BAT above the 640 KB limit
• CONFIG.SYS
–
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–
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DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE
DOS=HIGH,UMB
DEVICEHIGH .....
• AUTOEXEC.BAT
– LH .....
Virtual Memory - Used by Windows!
• Treats part of your disk as if it were memory
– Used by Windows and Windows applications, but not
by DOS
– Transparent to Windows applications
– Only used when physical memory is full
– DOS was designed for the Intel 8086 CPU, which did
not support Virtual Memory. Consequently, DOS
does not support Virtual Memory
– Virtual Memory is used by Windows 3.1 which was
designed to run on 286 and 386 CPUs (which do support
Virtual Memory)
Examining Memory
• Use the MEM or MSD commands
• System Info is available via the Help drop-down
menu of most modern Microsoft applications
Configuring Your PC
PC and DOS Essentials
The DOS Boot Sequence
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ROM-based diagnostics run first
Then the Boot Record is executed
IO.SYS loads
MS-DOS.SYS loads
If a CONFIG.SYS is present, this is then loaded
COMMAND.COM is then loaded
Lastly, if present, the AUTOEXEC.BAT is loaded
Conditional Booting
• To completely by-pass the DOS configuration
• First either boot or re-boot the computer
• When you see the message ‘Starting MS-DOS’ ...
– Either depress (and release) the F5 key
– or depress (and keep depressed) the Shift key
The CONFIG.SYS
• The CONFIG.SYS file is optional and is used to
customize the way your PC will work
– For instance, it may be used to set up the country
characteristics for countries other than the United States (DOS
is basically American and needs customization for proper use
outside the USA)
• Device drivers are software that extend the
function of DOS in a particular way
– For instance, if you have installed a particular tape drive, you
may need to install a tape device driver (supplied by the tape
manufacturer) that instructs DOS on how to talk to the tape
drive unit
The AUTOEXEC.BAT
• A batch file that executes automatically when you
boot the PC
• Sets items such as the PROMPT and PATH
C:\DOS\SMARTDRV.EXE
@ECHO OFF
PROMPT $p$g
PATH C:\WINDOWS;C:\DOS
SET TEMP=C:\temp
MODE CON CODEPAGE PREPARE=((437) C:\DOS\EGA.CPI)
MODE CON CODEPAGE SELECT=437
KEYB UK,,C:\DOS\KEYBOARD.SYS
The DOS PATH
• The PATH command is normally set from within
the AUTOEXEC.BAT
• Defines a search path for executable files or batch
files (i.e. files that run when you type in the
correct file name and press the Return key)
– It is important to remember that by default DOS always
searches the current directory first (i.e. the directory you are in
when you issue a command)
– The root directory of a disk will only be searched if it is the
current directory, or if it is specified in the PATH statement
– Held as an environment variable, within the DOS environment
• A small area of memory used for storing variables for use by DOS,
Windows or other applications
The DOS Environment
• The DOS Environment is a small area of memory
used by DOS, Windows and some other
applications to store used items of information
• Standard items include the Path, Prompt and
COMSPEC variables
• Windows uses the TEMP= variable to determine
where to store temporary files
• Use the SET command to view the contents of the
Environment
‘Loading High’
• Since the release of DOS 5 elements of DOS may
be loaded above 640 KB
• CONFIG.SYS
– Use the DEVICEHIGH statement
• AUTOEXEC.BAT
– Use the LH statement
• Allows you to free up Conventional Memory for
use by DOS application programs
Configuring a Windows-Based PC
• Most Windows configuration is set via the Control
Panel
Batch Files, I/O and Redirection
PC and DOS Essentials
What are Batch Files?
• Batch files allow you to assign
repetitive tasks to a small file
which once created may be run
as often as you wish
• Batch files have a .BAT file
extension
• The AUTOEXEC.BAT is a batch
file with the special property
that it will run automatically
each time you boot DOS
REM and ECHO
• REM
– This allows you to document a batch file
– Not displayed on the screen
REM message
• ECHO
– May be used to turn off echoing of batch file statements
ECHO OFF
– ECHO OFF often preceded by @, which turns echoing off for the
line containing it
@ECHO OFF
– May be used to display (echo) messages to the screen
ECHO message
– May be used in batch files to activate the system bleep
ECHO ^G
(CONTROL+G)
GOTO and CALL
• GOTO
– Allows you to go from one line to another, within the same batch file
– A single trip (no automatic return)
– You go to a label which is indicated by a preceeding colon (:)
•
•
•
•
:START
TYPE C:\AUTOEXEC.BAT
PAUSE
GOTO START
• CALL
– Used to transfer control from one batch file to another batch file
– When the second batch file has finished processing, control
automatically returns to the original batch file
PAUSE
• Used to temporarily suspend batch file
processing
• By default displays a message
‘Press any key to continue’
I/O, Device Names and Redirection
• Standard devices include:
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The console
The serial port
The parallel port
The console
The NUL device
TYPE AUTOEXEC.BAT > LPT1:
XCOPY A:\ C:\ > NUL
• Standard Output
– Informational output that is displayed on the console (screen) by
default
– May be re-directed to the NUL device
• Standard Error
– Information concerning errors that is displayed on the console
– Cannot be re-directed to the NUL device
Piping
• The output of one command is fed directly into a second
command, and will modify the output, which is then
displayed on the standard device (i.e. the screen)
• Used by certain DOS commands
– MORE
– FIND
– REPLACE
TYPE C:\WINDOWS\WIN.INI ¦ MORE
The output is modified so that it
is displayed one screen at a time
Advanced Batch File Concepts
PC and DOS Essentials
What are Variables?
• A variable is like a container such as a
cup
C:\DOS;C:\WINDOWS
– The cup is always called a cup, but the
contents of the cup can change
– For instance the cup may contain coffee or tea
OR C:\DOS
– But the container is still called CUP
– DOS can use this idea of a named container,
i.e. variable
• The DOS path is held in a container
called PATH, it is always called
Path, but as we know the contents of
the Path may be changed
PATH
Command Line Parameter Substitution
• This concept allows you to run the batch file and
specify parameters that are picked up by the
batch file and used within it
– Each parameter is separated by a space
BATCH_FILE Parameter1 Parameter2 Parameter3 ...
Environment Variable Substitution
• The DOS environment is a small area of memory used
for storing variables
• Environment variables include:
– PATH, PROMPT, TEMP, COMSPEC
• To set an Environment variable use the syntax:
– SET variable= value
• To put an Environment variable into a batch file use:
– %enviroment_variable_name%
• To add an Environment variable to the DOS path, use:
– PATH=%PATH%;%1
– NB: This assumes that the existing path does not end with a semicolon (;)
IF EXIST
• Used to detect the existence of a particular file
• NOTE that this command will NOT detect the
existence of a directory
IF EXIST C:\AUTOEXEC.BAT GOTO DONTCOPY
: DONTCOPY
IF ERRORLEVEL
• Some DOS commands issue
ERRORLEVEL reports on
completion
• Also called return codes or
exit codes
ERRORLEVEL is supported
by:
BACKUP
CHKDSK
CHOICE
DEFRAG
DELTREE
DISKCOMP
DISKCOPY
FIND
FORMAT
GRAFTABL
KEYB
MOVE
IF ERRORLEVEL 3 GOTO SOMTHING_WRONG_3
MSAV
REPLACE
IF ERRORLEVEL 2 GOTO SOMTHING_WRONG_2
RESTORE
SETVER
– An Error level of 0 normally
indicates success
– An Error level above 1 normally
indicates failure
IF ERRORLEVEL 1 GOTO SOMTHING_WRONG_1
IF ERRORLEVEL 0 GOTO NO_PROBLEM
XCOPY
DOSKEY Macros
• Use DOSKEY to create them
• DOSKEY TA TYPE C:\AUTOEXEC.BAT
• Similar to DOS-based batch files BUT held in
memory, not on the disk
• Faster than Batch files
• Volatile
• Load via the AUTOEXEC.BAT if you want to make
them more permanent
Printers
PC and DOS Essentials
Types of Laser Printer
PCL vs Postscript
• PCL (Printer Control Language)
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Not so good for DTP
Device dependent
Reasonably fast
PCL5 used in HP LaserJet 4 series
Normally used with resolution enhancement
• Postscript
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Much more flexible and configurable
Slower
More expensive hardware required
Ideal for graphics and DTP
Device resolution dependent
Printer Considerations
• Important items to consider when specifying a
printer are:
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Speed
Resolution
Resolution Image Enhancement
Printer memory
Duplex printing
Printer Drivers for DOS and Windows
• Each DOS program requires its own printer driver
• All Windows programs use a single Windows
printer driver
PRINTER
DRIVER
Security, Backups and Viruses
PC and DOS Essentials
What are Viruses?
Suddenly, I do
not feel so well!
• Viruses can cause permanent
loss of data
• Viruses spread from one PC to
another, even across networks
• ALWAYS use a virus checker
on your disks
Virus Protection Methods
DOS and Windows
• MSAV
– Run from the command line or
from the AUTOEXEC.BAT
• VSAFE
– TSR program
– Constantly on alert for
viruses
• Windows 3.1 is given
anti-virus tools by DOS
Backups
• Under DOS
– Use MSBACKUP
• In Windows
– Open the File Manager and
click on the Backup
command, located under
the Tools drop down menu
Perform REGULAR backups!
Fixing Errors On a Disk
• Disks are physical devices, and
disk drives are full of moving parts
• Like anything else, they are prone
to wear and tear as they get older
• CHKDSK /F and SCANDISK can
be used to fix a range of problems
that may occur on your disks
Use SCANDISK rather than CHKDSK it is safer and more effective
Windows Fundamentals
PC and DOS Essentials
The Advantages of Using Windows
• The Microsoft sales pitch
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Multitasking
Uses all available memory
Has a consistent User Interface
Allows programs to talk to each other
• The down side
– Prone to crashing
– Does not multitask in a sensible way
Select, then Manipulate!
• The basic rule when using Windows!
Components of a Window
• The Title Bar
• The Menu Bar
• Borders
Maximizing, Minimizing and Restoring
a Window
• Maximize
– Causes the program to fill the whole
screen
• Minimize
– Causes the program to be displayed
as an icon
• Restore
– Restores an icon to a window, or a full
screen program to a window
Moving and Re-sizing a Window
• Any program displayed as a window within
Microsoft Windows can be moved around on the
screen
• Any program displayed as a window within
Microsoft Windows can be re-sized either
horizontally, vertically, or in two dimensions at
the same time
Menus and Dialog Boxes
• All windows programs have drop down menus of
one sort or another. The drop down menus within
a Windows program allow you to interact with a
program. For instance, most applications have a
File drop down menu containing commands such
as Open, Save, or Exit
Multitasking Within Windows
• When you multitask programs under Windows on
your PC, they appear to run simultaneously
– In fact each program is allocated a small proportion of the
CPUs attention and whilst one program is running, the other
programs are temporarily suspended
– By default, all Windows applications will appear to run
simultaneously, whilst DOS programs will only run when in the
foreground
Using the Task List
• Displayed in a window and, as the name suggests,
lists all the tasks (i.e. programs) that are currently
running in memory
• Allows you to easily switch to any
of the programs listed in it, or
to close any program listed in it
• Can tile or cascade programs
– This causes each separate program that is
running to be displayed either side-by-side,
or in a layered fashion
• You can arrange the icons at the bottom of the
screen
The Program Manager, File Manager
and Control Panel
PC and DOS Essentials
Program Manager Groups
• A number of standard groups are installed by
default
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Main group
Accessories group
Games group
StartUp group
• Groups can be added, deleted or modified
Manipulating Groups and Adding
Programs
• Click on File and
select New
This dialog box is displayed when
you create a new program group
or program item
File Manager Terminology
• It is important to understand the terminology
associated with using the File Manager
Directories and Drives
• Make sure that you know how:
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To expand a directory level
To expand all directory levels
To indicate expandable branches
To collapse a directory level
To display a particular directory
To change the active disk drive
The Control Panel
• Allows you configure items including:
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Colors and Fonts
Ports
Mouse and Keyboard
Desktop
Printers
International settings
Date/Time
Sound and Drivers
386 Enhanced