it essentials - chapter 4 operating system fundamentals

IT Essentials IT Essentials -- Chapter 4Chapter 4

Operating System Operating System FundamentalsFundamentals

IT EssentialsIT Essentials -- Chapter 4Chapter 4

Operating System Fundamentals Operating System Fundamentals

Operating Systems (OS) are Operating Systems (OS) are software programs that control software programs that control thousands of operations, provide thousands of operations, provide an interface between the user an interface between the user and the computer, and run and the computer, and run applications. applications.


Operating System FundamentalsOperating System Fundamentals

Computers that are capable of Computers that are capable of handling concurrent users and handling concurrent users and multiple jobs are often called multiple jobs are often called network servers or simply network servers or simply "servers". Servers have operating "servers". Servers have operating systems installed called Network systems installed called Network Operating Systems (NOS). Operating Systems (NOS).



Three basic elements make up Three basic elements make up the major design components of the major design components of any operating system. any operating system.



Three basic elements make up Three basic elements make up the major design components of the major design components of any operating system. any operating system. – User interfaceUser interface – KernelKernel – File management systemFile management system



User interfaceUser interface – – A user interacts with A user interacts with the computer OS through the user interface. the computer OS through the user interface.

Simply put, the user interface is the part of Simply put, the user interface is the part of the operating system that a person can use the operating system that a person can use to issue commands by either typing them at to issue commands by either typing them at a command prompt or pointing and clicking a command prompt or pointing and clicking the mouse on the screen of a Graphical User the mouse on the screen of a Graphical User

Interface (GUI).Interface (GUI).



KernelKernel – – This is the core of the OS. This is the core of the OS.

The kernel is responsible for loading and The kernel is responsible for loading and running programs (processes) and for running programs (processes) and for managing input and output managing input and output



File management systemFile management system – – The The file management system is what the OS uses file management system is what the OS uses to organize and manage files. to organize and manage files.



Operating system functionsOperating system functions

– File and folder managementFile and folder management

When a file is saved, the operating system When a file is saved, the operating system saves it, attaches a name to it, and saves it, attaches a name to it, and remembers where it put the file in the remembers where it put the file in the hard drive for future use.hard drive for future use.




– Management of applications Management of applications

When a user requests a program, the When a user requests a program, the operating system locates the application operating system locates the application and loads it into the primary memory or and loads it into the primary memory or RAM of the computer. RAM of the computer.




– Support for built-in utility programsSupport for built-in utility programs

Utility programs are programs that the OS Utility programs are programs that the OS uses to maintain and repair itself. These uses to maintain and repair itself. These programs help identify problems, locate programs help identify problems, locate lost files, repair damaged files, and backup lost files, repair damaged files, and backup data.data.




– Access control to computer hardwareAccess control to computer hardware

The OS sits between the programs and the The OS sits between the programs and the Basic Input/Output System (BIOS). All Basic Input/Output System (BIOS). All programs that need hardware resources programs that need hardware resources must first go through the operating must first go through the operating system. The OS in turn can either access system. The OS in turn can either access the hardware through the BIOS or through the hardware through the BIOS or through the device drivers.the device drivers.



Operating system typesOperating system types

– Multiuser – Multiuser – Two or more users running Two or more users running programs and sharing peripheral devices, programs and sharing peripheral devices, such as a printer, at the same time.such as a printer, at the same time.




– Multitasking – Multitasking – The capability of a The capability of a computer to run multiple applications at computer to run multiple applications at the same time.the same time.




– Multiprocessing – Multiprocessing – Allows a computer to Allows a computer to have two or more CPUs (Central have two or more CPUs (Central Processing Unit) that programs share.Processing Unit) that programs share.




– Multithreading – Multithreading – The capability of a The capability of a program to be broken into smaller parts program to be broken into smaller parts that can be loaded as needed by the OS. that can be loaded as needed by the OS. Multithreading allows individual programs Multithreading allows individual programs to be multitasked.to be multitasked.



MS-DOSMS-DOS– DOS is a collection of programs and DOS is a collection of programs and

commands used to control the commands used to control the overall computer operation in a disk-overall computer operation in a disk-based system. based system.

– There are three distinct sections that There are three distinct sections that make up the disk operating system. make up the disk operating system. These include: These include:



MS-DOSMS-DOS– Boot filesBoot files – Used during the boot process – Used during the boot process

(that is, start-up). (that is, start-up).





– File management filesFile management files – Enables the – Enables the system to manage the data that it holds. system to manage the data that it holds.





– File management filesFile management files – Enables the – Enables the system to manage the data that it holds. system to manage the data that it holds.

– Utility filesUtility files – Enables the user to manage – Enables the user to manage system resources, troubleshoot the system resources, troubleshoot the system, and configure the system settings.system, and configure the system settings.



Elements of DOSElements of DOS

– DOS is a command line operating system, DOS is a command line operating system, it is not user-friendly. The best way to it is not user-friendly. The best way to learn DOS is to use it.learn DOS is to use it.




– DOS is a command line operating system, DOS is a command line operating system, it is not user-friendly. The best way to it is not user-friendly. The best way to learn DOS is to use it. learn DOS is to use it.

– DOS can only run one program at a time. It DOS can only run one program at a time. It is not multitasking. is not multitasking.




– DOS is a command line operating system, DOS is a command line operating system, it is not user-friendly. The best way to it is not user-friendly. The best way to learn DOS is to use it. learn DOS is to use it.


– DOS can only run small programs and has DOS can only run small programs and has memory limitations.memory limitations.




– DOS is a command line operating system, it DOS is a command line operating system, it is not user-friendly. The best way to learn is not user-friendly. The best way to learn DOS is to use it. DOS is to use it.


– DOS can only run small programs and has DOS can only run small programs and has memory limitations. memory limitations.

– DOS is an essential tool for IT professionals DOS is an essential tool for IT professionals and is used extensively for troubleshooting. and is used extensively for troubleshooting.



FilesFiles

– A file is simply a block of logically related A file is simply a block of logically related data that is given a single name and data that is given a single name and treated as a single unit.treated as a single unit.



File AttributesFile Attributes

– All files have attributes. All files have attributes. – These are a set of parameters that These are a set of parameters that

describe a file. Given the attributes of a describe a file. Given the attributes of a file, it is possible to determine the nature file, it is possible to determine the nature of the file. of the file.




– Hidden FileHidden File – The user will not see this type of file – The user will not see this type of file with any kind of normal file search in a DOS with any kind of normal file search in a DOS

environment.environment.




– Hidden FileHidden File – The user will not see this type of file – The user will not see this type of file with any kind of normal file search in a DOS with any kind of normal file search in a DOS environment. environment.

– Read OnlyRead Only – The user can open and read this type – The user can open and read this type of file but cannot write or modify the file in any of file but cannot write or modify the file in any

way.way.





– Read OnlyRead Only – The user can open and read this type – The user can open and read this type of file but cannot write or modify the file in any of file but cannot write or modify the file in any way. way.

– Archive (backup) statusArchive (backup) status – Used by backup – Used by backup utilities to determine if a file needs to be backed up utilities to determine if a file needs to be backed up or not. or not.





– Read OnlyRead Only – The user can open and read this type of – The user can open and read this type of file but cannot write or modify the file in any way. file but cannot write or modify the file in any way.

– Archive (backup) statusArchive (backup) status – Used by backup utilities – Used by backup utilities to determine if a file needs to be backed up or not. to determine if a file needs to be backed up or not.

– System FileSystem File – A file needed by the DOS operating – A file needed by the DOS operating system for a successful bootup.system for a successful bootup.



Internal versus External DOS CommandsInternal versus External DOS Commands – Commands that are built into the Commands that are built into the

operating system are internal.operating system are internal.

– Commands that must be executed Commands that must be executed from a file are external. from a file are external.



Command LineCommand Line

– the main user interface is the the main user interface is the command line. The command line is command line. The command line is the space immediately following the the space immediately following the DOS prompt. DOS prompt.



A DOS boot disk is just a floppy disk A DOS boot disk is just a floppy disk with three necessary system files on it: with three necessary system files on it:



A DOS boot disk is just a floppy disk A DOS boot disk is just a floppy disk with three necessary system files on it: with three necessary system files on it:

COMMAND.COM COMMAND.COM IO.SYS IO.SYS MSDOS.SYSMSDOS.SYS



To create a bootable disk…To create a bootable disk…

– Insert a blank floppy disk in the drive. Insert a blank floppy disk in the drive. – At the command prompt type At the command prompt type

FORMAT A: /s and press FORMAT A: /s and press EnterEnter. .

oror



To create a bootable disk…To create a bootable disk…

– Insert a blank floppy disk in the drive. Insert a blank floppy disk in the drive. – At the command prompt type FORMAT At the command prompt type FORMAT

A: /s and press A: /s and press EnterEnter. .

oror– If the disk is already formatted, type SYS If the disk is already formatted, type SYS

A: and press A: and press EnterEnter..



DOS requires these files in this order DOS requires these files in this order to boot your system:to boot your system:– BIOSBIOS– bootstrapbootstrap– io.sysio.sys– msdos.sysmsdos.sys– config.sysconfig.sys– command.comcommand.com– autoexec.batautoexec.bat



During the boot process, while the MS-DOS During the boot process, while the MS-DOS message "Starting DOS..." is on, the screen message "Starting DOS..." is on, the screen special function keys are available to alter special function keys are available to alter the loading process of CONFIG.SYS (and an the loading process of CONFIG.SYS (and an option for AUTOEXEC.BAT).option for AUTOEXEC.BAT).

F5 & F8F5 & F8



– F5F5 (or Left Shift key) (or Left Shift key)

Skips CONFIG.SYS file (including Skips CONFIG.SYS file (including AUTOEXEC.BAT files, if this option is AUTOEXEC.BAT files, if this option is chosen). chosen).

– F8F8

Proceeds through the CONFIG.SYS (and Proceeds through the CONFIG.SYS (and AUTOEXEC.BAT, if needed) files one step AUTOEXEC.BAT, if needed) files one step at a time waiting for Confirmation from the at a time waiting for Confirmation from the user.user.



SYSEDIT –SYSEDIT –

is a standard text editor used to is a standard text editor used to edit system configuration files edit system configuration files such as Config.sys and such as Config.sys and Autoexec.bat. Autoexec.bat.



Conventional Memory Conventional Memory 0 and 640KB0 and 640KB Also known as base memory. Also known as base memory. This is the area where MS-DOS programs This is the area where MS-DOS programs

normally run. normally run. In older DOS machines, this is the only In older DOS machines, this is the only

memory available for running the OS files, memory available for running the OS files, application programs, memory resident application programs, memory resident routines, and device drivers. Memory-resident routines, and device drivers. Memory-resident routines include Terminate-and-Stay-Resident routines include Terminate-and-Stay-Resident (TSR) Programs such as mouse and CD-ROM (TSR) Programs such as mouse and CD-ROM drivers. drivers.



Upper Memory/Expanded Memory Upper Memory/Expanded Memory 640KB to 1024KB640KB to 1024KB Also known as Reserved Memory.Also known as Reserved Memory. Upper memory is available in the form of Upper memory is available in the form of

Upper Memory Blocks (UMBs). Programs that Upper Memory Blocks (UMBs). Programs that run here include system BIOS, plug and play run here include system BIOS, plug and play BIOS, video BIOS and video RAM. BIOS, video BIOS and video RAM.

These addresses are only available if an These addresses are only available if an appropriate memory manager such as appropriate memory manager such as Emm386.EXE is installed during the startup Emm386.EXE is installed during the startup process. process.



Extended Memory Extended Memory Beyond the 1 MB limit.Beyond the 1 MB limit. Generally referred to as Extended Memory. Generally referred to as Extended Memory. This area of memory is also called Extended This area of memory is also called Extended

Memory Specification (XMS). XMS is the Memory Specification (XMS). XMS is the primary memory area used by Windows 9x. A primary memory area used by Windows 9x. A device driver that is loaded by the OS device driver that is loaded by the OS controls this memory area. Windows 9x loads controls this memory area. Windows 9x loads the XMS driver called Himem.sys during the XMS driver called Himem.sys during startup. Once loaded, Himem.sys makes startup. Once loaded, Himem.sys makes extended memory available to the Windows extended memory available to the Windows 9x and other compatible MS-DOS programs. 9x and other compatible MS-DOS programs.



High Memory High Memory Once the XMS driver is loaded, extended Once the XMS driver is loaded, extended memory becomes available to the OS. When memory becomes available to the OS. When this happens, the first 64KB of extended this happens, the first 64KB of extended memory is called the High Memory Area (HMA). memory is called the High Memory Area (HMA).

Typically, the XMS driver (Himem.sys) activates Typically, the XMS driver (Himem.sys) activates the DOS=HIGH option, enabling it to copy the the DOS=HIGH option, enabling it to copy the MS-DOS kernel used by Windows 9x into the MS-DOS kernel used by Windows 9x into the HMA. The point therefore, is that DOS uses the HMA. The point therefore, is that DOS uses the HMA, and by doing so, frees up more HMA, and by doing so, frees up more conventional memory for use by applications.conventional memory for use by applications.



Memory management toolsMemory management tools

– EMM386.EXEEMM386.EXE – This memory manager – This memory manager emulates expanded memory and makes emulates expanded memory and makes upper memory available for use by the OS. upper memory available for use by the OS.




– HIMEM.SYS – HIMEM.SYS – Load this device driver to Load this device driver to convert memory starting at 1MB available convert memory starting at 1MB available as XMS or extended memory. It is loaded as XMS or extended memory. It is loaded from the config.sys file. from the config.sys file.

– The syntax for this command is The syntax for this command is DEVICE=C:\DOS\HIMEM.SYS. DEVICE=C:\DOS\HIMEM.SYS.




– DOS=HIGHDOS=HIGH – This option is added into the – This option is added into the Config.sys file to tell the OS to move a Config.sys file to tell the OS to move a portion of itself (such as MS-DOS Kernel) portion of itself (such as MS-DOS Kernel) into the high memory area. It is usually into the high memory area. It is usually combined with DOS=UMB to tell it to combined with DOS=UMB to tell it to create an upper memory block using the create an upper memory block using the syntax DOS=HIGH, UMB.syntax DOS=HIGH, UMB.




DEVICEHIGH/LOADHIGHDEVICEHIGH/LOADHIGH – – – DEVICEHIGH (used in Config.sys) and DEVICEHIGH (used in Config.sys) and

LOADHIGH (used in Autoexec.bat) both put LOADHIGH (used in Autoexec.bat) both put upper memory blocks to use, once HIMEM.SYS upper memory blocks to use, once HIMEM.SYS and Emm386.exe have been loaded. and Emm386.exe have been loaded.

To load a mouse driver high, for example, use To load a mouse driver high, for example, use this this

syntax: DEVICEHIGH=C: \DOS\MOUSE.SYS syntax: DEVICEHIGH=C: \DOS\MOUSE.SYS



Other types of memoryOther types of memory

– Virtual Memory: Virtual Memory: Swap File in Windows 9xSwap File in Windows 9x Page File in Windows 2000Page File in Windows 2000

– Hard disk drive space is manipulated to Hard disk drive space is manipulated to seem like RAM.seem like RAM.



Other types of memoryOther types of memory

– RAM Drive RAM Drive Setting aside a portion of RAM to emulate Setting aside a portion of RAM to emulate a harddrive is a RAM drive. a harddrive is a RAM drive.

– For example, on a machine that has a hard For example, on a machine that has a hard drive partitioned into drives C and D, a drive partitioned into drives C and D, a RAM drive of 4 MB (4096 KB) can be RAM drive of 4 MB (4096 KB) can be created as E with the command:created as E with the command:

– DEVICE=C: \DOS\RAMDRIVE.SYS 4096DEVICE=C: \DOS\RAMDRIVE.SYS 4096



Memory conflicts Memory conflicts – General Protection Fault or GPFGeneral Protection Fault or GPF– Memory conflicts can be caused by Memory conflicts can be caused by

two memory managers running at two memory managers running at the same time. the same time.

– This conflict results in the blue This conflict results in the blue screen of death.screen of death.



Real ModeReal Mode Real mode memory addressing means that Real mode memory addressing means that software, such as DOS or its applications, can software, such as DOS or its applications, can address only 1,024 KB (1 MB) of RAM. In address only 1,024 KB (1 MB) of RAM. In other words, real mode means that the other words, real mode means that the microprocessor chip addresses the first 1,024 microprocessor chip addresses the first 1,024 bytes of "conventional and upper memory" bytes of "conventional and upper memory" by actually assigning real addresses to real by actually assigning real addresses to real locations in memory. locations in memory.



Protected ModeProtected Mode – Protected mode allows one program to fail Protected mode allows one program to fail

without bringing down the whole system.without bringing down the whole system.



Protected ModeProtected Mode – Protected mode allows one program to fail Protected mode allows one program to fail

without bringing down the whole system. without bringing down the whole system. – The theory behind protected mode is that The theory behind protected mode is that

what happens in one area of memory has what happens in one area of memory has no effect on other programs.no effect on other programs.



Protected Mode Protected Mode – Protected mode allows one program to fail Protected mode allows one program to fail


what happens in one area of memory has what happens in one area of memory has no effect on other programs. no effect on other programs.

– When running in protected mode, a When running in protected mode, a program is limited to its own memory program is limited to its own memory space allocation, but it can access memory space allocation, but it can access memory above 1MB. above 1MB.



Protected Mode Protected Mode – Protected mode allows one program to fail Protected mode allows one program to fail


what happens in one area of memory has no what happens in one area of memory has no effect on other programs. effect on other programs.

– When running in protected mode, a program When running in protected mode, a program is limited to its own memory space is limited to its own memory space allocation, but it can access memory above allocation, but it can access memory above 1MB. 1MB.

– Just about every operating system other Just about every operating system other than DOS runs in protected mode.than DOS runs in protected mode.



Before you take your online exam Before you take your online exam review the common DOS review the common DOS commands.commands.

it essentials - chapter 4 operating system fundamentals

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