IT Essentials - Chapter 4
Operating System Fundamentals
IT Essentials
- Chapter 4
Operating System Fundamentals
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Operating Systems (OS) are software
programs that control thousands of
operations, provide an interface
between the user and the computer,
and run applications.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Computers that are capable of
handling concurrent users and multiple
jobs are often called network servers
or simply "servers". Servers have
operating systems installed called
Network Operating Systems (NOS).
IT Essentials
- Chapter 4
Operating System Fundamentals
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Three basic elements make up the
major design components of any
operating system.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Three basic elements make up the
major design components of any
operating system.
– User interface
– Kernel
– File management system
IT Essentials
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Operating System Fundamentals
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User interface –
A user interacts with the
computer OS through the user interface.
Simply put, the user interface is the part of the
operating system that a person can use to issue
commands by either typing them at a command
prompt or pointing and clicking the mouse on the
screen of a Graphical User Interface (GUI).
IT Essentials
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Operating System Fundamentals
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Kernel –
This is the core of the OS.
The kernel is responsible for loading and running
programs (processes) and for managing input and
output
IT Essentials
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Operating System Fundamentals
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File management system –
The file
management system is what the OS uses to
organize and manage files.
IT Essentials
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Operating System Fundamentals
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Operating system functions
– File and folder management
When a file is saved, the operating system saves
it, attaches a name to it, and remembers where
it put the file in the hard drive for future use.
IT Essentials
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Operating System Fundamentals
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Operating system functions
– Management of applications
When a user requests a program, the operating
system locates the application and loads it into
the primary memory or RAM of the computer.
IT Essentials
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Operating System Fundamentals
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Operating system functions
– Support for built-in utility programs
Utility programs are programs that the OS uses
to maintain and repair itself. These programs
help identify problems, locate lost files, repair
damaged files, and backup data.
IT Essentials
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Operating System Fundamentals
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Operating system functions
– Access control to computer hardware
The OS sits between the programs and the Basic
Input/Output System (BIOS). All programs that
need hardware resources must first go through
the operating system. The OS in turn can either
access the hardware through the BIOS or
through the device drivers.
IT Essentials
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Operating System Fundamentals
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Operating system types
– Multiuser – Two or more users running
programs and sharing peripheral devices, such
as a printer, at the same time.
IT Essentials
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Operating System Fundamentals
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Operating system types
– Multitasking – The capability of a computer to
run multiple applications at the same time.
IT Essentials
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Operating System Fundamentals
Operating system types
– Multiprocessing – Allows a computer to have
two or more CPUs (Central Processing Unit) that
programs share.
IT Essentials
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Operating System Fundamentals
Operating system types
– Multithreading – The capability of a program
to be broken into smaller parts that can be
loaded as needed by the OS. Multithreading
allows individual programs to be multitasked.
IT Essentials
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Operating System Fundamentals
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MS-DOS
– DOS is a collection of programs and
commands used to control the overall
computer operation in a disk-based
system.
– There are three distinct sections that
make up the disk operating system.
These include:
IT Essentials
- Chapter 4
Operating System Fundamentals
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MS-DOS
– Boot files – Used during the boot process (that
is, start-up).
IT Essentials
- Chapter 4
Operating System Fundamentals
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MS-DOS
– Boot files – Used during the boot process (that
is, start-up).
– File management files – Enables the system
to manage the data that it holds.
IT Essentials
- Chapter 4
Operating System Fundamentals
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MS-DOS
– Boot files – Used during the boot process (that
is, start-up).
– File management files – Enables the system
to manage the data that it holds.
– Utility files – Enables the user to manage
system resources, troubleshoot the system, and
configure the system settings.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Elements of DOS
– DOS is a command line operating system, it is
not user-friendly. The best way to learn DOS is
to use it.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Elements of DOS
– DOS is a command line operating system, it is
not user-friendly. The best way to learn DOS is
to use it.
– DOS can only run one program at a time. It is
not multitasking.
IT Essentials
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Operating System Fundamentals
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Elements of DOS
– DOS is a command line operating system, it is
not user-friendly. The best way to learn DOS is
to use it.
– DOS can only run one program at a time. It is
not multitasking.
– DOS can only run small programs and has
memory limitations.
IT Essentials
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Operating System Fundamentals
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Elements of DOS
– DOS is a command line operating system, it is
not user-friendly. The best way to learn DOS is
to use it.
– DOS can only run one program at a time. It is
not multitasking.
– DOS can only run small programs and has
memory limitations.
– DOS is an essential tool for IT professionals and
is used extensively for troubleshooting.
IT Essentials
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Operating System Fundamentals
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Files
– A file is simply a block of logically related data
that is given a single name and treated as a
single unit.
IT Essentials
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Operating System Fundamentals
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File Attributes
– All files have attributes.
– These are a set of parameters that describe a
file. Given the attributes of a file, it is possible to
determine the nature of the file.
IT Essentials
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Operating System Fundamentals
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File Attributes
– Hidden File – The user will not see this type of file with
any kind of normal file search in a DOS environment.
IT Essentials
- Chapter 4
Operating System Fundamentals
 File
Attributes
– Hidden File – The user will not see this type of file with
any kind of normal file search in a DOS environment.
– Read Only – The user can open and read this type of file
but cannot write or modify the file in any way.
IT Essentials
- Chapter 4
Operating System Fundamentals
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File Attributes
– Hidden File – The user will not see this type of file with
any kind of normal file search in a DOS environment.
– Read Only – The user can open and read this type of file
but cannot write or modify the file in any way.
– Archive (backup) status – Used by backup utilities to
determine if a file needs to be backed up or not.
IT Essentials
- Chapter 4
Operating System Fundamentals
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File Attributes
– Hidden File – The user will not see this type of file with
any kind of normal file search in a DOS environment.
– Read Only – The user can open and read this type of file
but cannot write or modify the file in any way.
– Archive (backup) status – Used by backup utilities to
determine if a file needs to be backed up or not.
– System File – A file needed by the DOS operating system
for a successful bootup.
IT Essentials
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Operating System Fundamentals
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Internal versus External DOS Commands
– Commands that are built into the
operating system are internal.
– Commands that must be executed from a
file are external.
IT Essentials
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Operating System Fundamentals
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Command Line
– the main user interface is the command
line. The command line is the space
immediately following the DOS prompt.
IT Essentials
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Operating System Fundamentals
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A DOS boot disk is just a floppy disk with
three necessary system files on it:
IT Essentials
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Operating System Fundamentals
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A DOS boot disk is just a floppy disk with
three necessary system files on it:
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COMMAND.COM
IO.SYS
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MSDOS.SYS
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IT Essentials
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Operating System Fundamentals
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To create a bootable disk…
– Insert a blank floppy disk in the drive.
– At the command prompt type
FORMAT A: /s and press Enter.
or
IT Essentials
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Operating System Fundamentals
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To create a bootable disk…
– Insert a blank floppy disk in the drive.
– At the command prompt type FORMAT A: /s and
press Enter.
or
– If the disk is already formatted, type SYS A: and
press Enter.
IT Essentials
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Operating System Fundamentals
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DOS requires these files in this order to boot
your system:
–
–
–
–
–
–
–
BIOS
bootstrap
io.sys
msdos.sys
config.sys
command.com
autoexec.bat
IT Essentials
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Operating System Fundamentals
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During the boot process, while the MS-DOS
message "Starting DOS..." is on, the screen special
function keys are available to alter the loading
process of CONFIG.SYS (and an option for
AUTOEXEC.BAT).
F5 & F8
IT Essentials
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Operating System Fundamentals
– F5 (or Left Shift key)
Skips CONFIG.SYS file (including AUTOEXEC.BAT
files, if this option is chosen).
– F8
Proceeds through the CONFIG.SYS (and
AUTOEXEC.BAT, if needed) files one step at a
time waiting for Confirmation from the user.
IT Essentials
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Operating System Fundamentals
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SYSEDIT –
is a standard text editor used to edit
system configuration files such as
Config.sys and Autoexec.bat.
IT Essentials
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Operating System Fundamentals
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Conventional Memory
0 and 640KB
Also known as base memory.
This is the area where MS-DOS programs normally
run.
In older DOS machines, this is the only memory
available for running the OS files, application
programs, memory resident routines, and device
drivers. Memory-resident routines include
Terminate-and-Stay-Resident (TSR) Programs such
as mouse and CD-ROM drivers.
IT Essentials
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Operating System Fundamentals
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Upper Memory/Expanded Memory
640KB to 1024KB
Also known as Reserved Memory.
Upper memory is available in the form of Upper
Memory Blocks (UMBs). Programs that run here
include system BIOS, plug and play BIOS, video
BIOS and video RAM.
These addresses are only available if an appropriate
memory manager such as Emm386.EXE is installed
during the startup process.
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Operating System Fundamentals
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Extended Memory
Beyond the 1 MB limit.
Generally referred to as Extended Memory.
This area of memory is also called Extended
Memory Specification (XMS). XMS is the primary
memory area used by Windows 9x. A device driver
that is loaded by the OS controls this memory area.
Windows 9x loads the XMS driver called Himem.sys
during startup. Once loaded, Himem.sys makes
extended memory available to the Windows 9x and
other compatible MS-DOS programs.
IT Essentials
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Operating System Fundamentals
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High Memory
Once the XMS driver is loaded, extended memory
becomes available to the OS. When this happens,
the first 64KB of extended memory is called the
High Memory Area (HMA).
Typically, the XMS driver (Himem.sys) activates the
DOS=HIGH option, enabling it to copy the MS-DOS
kernel used by Windows 9x into the HMA. The point
therefore, is that DOS uses the HMA, and by doing
so, frees up more conventional memory for use by
applications.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Memory management tools
– EMM386.EXE – This memory manager
emulates expanded memory and makes upper
memory available for use by the OS.
IT Essentials
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Operating System Fundamentals
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Memory management tools
– HIMEM.SYS – Load this device driver to
convert memory starting at 1MB available as
XMS or extended memory. It is loaded from the
config.sys file.
– The syntax for this command is
DEVICE=C:\DOS\HIMEM.SYS.
IT Essentials
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Operating System Fundamentals
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Memory management tools
– DOS=HIGH – This option is added into the
Config.sys file to tell the OS to move a portion of
itself (such as MS-DOS Kernel) into the high
memory area. It is usually combined with
DOS=UMB to tell it to create an upper memory
block using the syntax DOS=HIGH, UMB.
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Operating System Fundamentals
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Memory management tools
DEVICEHIGH/LOADHIGH –
– DEVICEHIGH (used in Config.sys) and
LOADHIGH (used in Autoexec.bat) both put
upper memory blocks to use, once HIMEM.SYS
and Emm386.exe have been loaded.
To load a mouse driver high, for example, use this
syntax: DEVICEHIGH=C: \DOS\MOUSE.SYS
IT Essentials
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Operating System Fundamentals
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Other types of memory
– Virtual Memory:
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Swap File in Windows 9x
Page File in Windows 2000
– Hard disk drive space is manipulated to seem
like RAM.
IT Essentials
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Operating System Fundamentals
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Other types of memory
– RAM Drive
Setting aside a portion of RAM to emulate a
harddrive is a RAM drive.
– For example, on a machine that has a hard drive
partitioned into drives C and D, a RAM drive of 4
MB (4096 KB) can be created as E with the
command:
– DEVICE=C: \DOS\RAMDRIVE.SYS 4096
IT Essentials
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Operating System Fundamentals
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Memory conflicts
– General Protection Fault or GPF
– Memory conflicts can be caused by two
memory managers running at the same
time.
– This conflict results in the blue screen of
death.
IT Essentials
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Operating System Fundamentals
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Real Mode
Real mode memory addressing means that
software, such as DOS or its applications, can
address only 1,024 KB (1 MB) of RAM. In other
words, real mode means that the microprocessor
chip addresses the first 1,024 bytes of
"conventional and upper memory" by actually
assigning real addresses to real locations in
memory.
IT Essentials
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Operating System Fundamentals
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Protected Mode
– Protected mode allows one program to fail
without bringing down the whole system.
IT Essentials
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Operating System Fundamentals
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Protected Mode
– Protected mode allows one program to fail
without bringing down the whole system.
– The theory behind protected mode is that what
happens in one area of memory has no effect on
other programs.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Protected Mode
– Protected mode allows one program to fail
without bringing down the whole system.
– The theory behind protected mode is that what
happens in one area of memory has no effect on
other programs.
– When running in protected mode, a program is
limited to its own memory space allocation, but
it can access memory above 1MB.
IT Essentials
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Operating System Fundamentals
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Protected Mode
– Protected mode allows one program to fail
without bringing down the whole system.
– The theory behind protected mode is that what
happens in one area of memory has no effect on
other programs.
– When running in protected mode, a program is
limited to its own memory space allocation, but
it can access memory above 1MB.
– Just about every operating system other than
DOS runs in protected mode.
IT Essentials
- Chapter 4
Operating System Fundamentals
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Before you take your online exam
review the common DOS commands.