An Overview of the PC

1
An Overview of the PC

• PC and DOS Essentials

2
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!

3
The Operating SystemDOS 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

4
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

5
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

6
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

7
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)

8
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

9
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

10
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

11
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

12
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

13
Directories and Files

• PC and DOS Essentials

14
What are Directories?

• A convenient way of dividing up your hard disk
• Each application can be kept in its own
  directory
• The root directory is called CD\
• A single . represents the current directory
• A double .. represents the parent directory

15
Manipulating Directories Under DOS

• Directory commands include
• MD
• CD
• RD
• TREE
• DELTREE

Please take care using DELTREE
DELTREE
16
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

17
The DIR Command

• Switches include
• /w
• /p
• /s
• /?

18
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)

19
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-
• \ ? lt gt
• 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

20
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

21
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

22
Renaming, Deleting and Undeleting Files
Give me my files back!

• DEL
• Deletes files
• REN
• Renames files
• UNDELETE
• Undeletes deleted files

Beware of accidental file deletion!
23
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!
24
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

25
Viewing and Finding Files Within DOS

• View with the TYPE command
• Use DIR/s to find

26
Viewing and Finding Files Using the Windows File
Manager

• 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
27
Manipulating File Attributes

• Attributes
• Read Only
• Archive
• System
• Hidden
• Use of ATTRIB
• R Read-only
• A Archive
• S System
• H Hidden
• In Windows manipulated via the File Manager
• File/Properties

28
Disk Fundamentals

• PC and DOS Essentials

29
Types - Floppy Disks (Diskettes) and Hard Disks

• Hard disks
• Non-removable
• Inside your PC
• Very fast
• Hold large amounts of data
• Diskettes
• Removable
• Hold up to 1.44 MB
• Very slow

30
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

31
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.

32
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

33
Diskette Formatting Considerations

• System and non-system diskettes
• Quick formatting

?
Non-System Disk!

34
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

35
Copying and Labelling Diskettes

• DISKCOPY
• Uses identical source and target diskettes

36
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
37
Buffers

• Used to speed up access from the disk
• Set up via the CONFIG.SYS

38
SmartDrive

• Setup via the AUTOEXEC.BAT
• Can increase to AND from the hard disk

39
Disk Compression DBLSPACE and DRVSPACE

• Compresses data held on a disk, and increases the
  storage capacity
• Is it safe?
• What about disk performance?

After
Before
40
Disk Structures

• Sides
• Sectors
• Tracks
• Clusters

41
The DOS Boot Sequence

• The boot record
• Two hidden system files
• CONFIG.SYS
• COMMAND.COM
• AUTOEXEC.BAT

42
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)

43
Memory Fundamentals

• PC and DOS Essentials

44
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

45
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

Its not 1981 anymore!
DOS
46
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

47
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

48
Expanded MemoryAn 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

DEVICEC\DOS\EMM386.EXE
49
The Upper Memory Blocks and the High Memory Area

• The UMB space is located between 640 KB and 1 MB
• The HMA is a 64 KB area just above 1 MB

HMA
UMBs
Conventional Memory
50
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
• DEVICEC\DOS\HIMEM.SYS
• DEVICEC\DOS\EMM386.EXE
• DOSHIGH,UMB
• DEVICEHIGH .....
• AUTOEXEC.BAT
• LH .....

51
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)

52
Examining Memory

• Use the MEM or MSD commands
• System Info is available via the Help drop-down
  menu of most modern Microsoft applications

53
Configuring Your PC

• PC and DOS Essentials

54
The DOS Boot Sequence

• 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

55
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

56
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

57
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 _at_ECHO OFF PROMPT pg PATH
C\WINDOWSC\DOS SET TEMPC\temp MODE CON
CODEPAGE PREPARE((437) C\DOS\EGA.CPI) MODE CON
CODEPAGE SELECT437 KEYB UK,,C\DOS\KEYBOARD.SYS
58
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

59
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

60
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

61
Configuring a Windows-Based PC

• Most Windows configuration is set via the Control
  Panel

62
Batch Files, I/O and Redirection

• PC and DOS Essentials

63
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

64
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 _at_, which turns echoing
  off for the line containing it
• _at_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 (CONTROLG)

65
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

66
PAUSE

• Used to temporarily suspend batch file
  processing
• By default displays a message
• Press any key to continue

67
I/O, Device Names and Redirection

• Standard devices include
• The console
• The serial port
• The parallel port
• The console
• The NUL device
• 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

TYPE AUTOEXEC.BAT gt LPT1 XCOPY A\ C\ gt NUL
68
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
69
Advanced Batch File Concepts

• PC and DOS Essentials

70
What are Variables?

• A variable is like a container such as a cup
• The cup is always called a cup, but the contents
  of the cup can change
• For instance the cup may contain coffee or tea
• 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

C\DOSC\WINDOWS
OR
C\DOS
PATH
71
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 ...
72
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
• PATHPATH1
• NB This assumes that the existing path does not
  end with a semi-colon ()

73
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
74
IF ERRORLEVEL

• Some DOS commands issue ERRORLEVEL reports on
  completion
• Also called return codes or exit codes
• An Error level of 0 normally indicates success
• An Error level above 1 normally indicates failure

ERRORLEVEL is supported by BACKUP CHKDSK CHOICE
DEFRAG DELTREE DISKCOMP DISKCOPY FIND FORMAT GRAFT
ABL KEYB MOVE MSAV REPLACE RESTORE SETVER XCOPY
IF ERRORLEVEL 3 GOTO SOMTHING_WRONG_3 IF
ERRORLEVEL 2 GOTO SOMTHING_WRONG_2 IF ERRORLEVEL
1 GOTO SOMTHING_WRONG_1 IF ERRORLEVEL 0 GOTO
NO_PROBLEM
75
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

76
Printers

• PC and DOS Essentials

77
Types of Laser PrinterPCL vs Postscript

• PCL (Printer Control Language)
• Not so good for DTP
• Device dependent
• Reasonably fast
• PCL5 used in HP LaserJet 4 series
• Normally used with resolution enhancement
• Postscript
• Much more flexible and configurable
• Slower
• More expensive hardware required
• Ideal for graphics and DTP
• Device resolution dependent

78
Printer Considerations

• Important items to consider when specifying a
  printer are
• Speed
• Resolution
• Resolution Image Enhancement
• Printer memory
• Duplex printing

79
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
80
Security, Backups and Viruses

• PC and DOS Essentials

81
What are Viruses?

• 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

82
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

83
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!
84
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
85
Windows Fundamentals

• PC and DOS Essentials

86
The Advantages of Using Windows

• The Microsoft sales pitch
• 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

87
Select, then Manipulate!

• The basic rule when using Windows!

88
Components of a Window

• The Title Bar
• The Menu Bar
• Borders

89
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

90
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

91
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

92
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

93
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

94
The Program Manager, File Manager and Control
Panel

• PC and DOS Essentials

95
Program Manager Groups

• A number of standard groups are installed by
  default
• Main group
• Accessories group
• Games group
• StartUp group
• Groups can be added, deleted or modified

96
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
97
File Manager Terminology

• It is important to understand the terminology
  associated with using the File Manager

98
Directories and Drives

• Make sure that you know how
• 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

99
The Control Panel

• Allows you configure items including
• Colors and Fonts
• Ports
• Mouse and Keyboard
• Desktop
• Printers
• International settings
• Date/Time
• Sound and Drivers
• 386 Enhanced