Most modern operating systems incorporate Most modern operating systems incorporate these five componentsthese five components

User interface(shell)

Devicemanagement

Filemanagement

Memorymanagement

Processormanagement

User Interface (Shell)User Interface (Shell)

Provides a mechanism for the user and application programs to communicate with the operating system.– Types Of User Interfaces:

Command – Executes single line commands Menu – Presents a list of single line commands GUI – Allows the user to issue commands by

clicking on icons or selecting options from a menu

Voice – User issues commands orally Web

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The User Interface

Fig. 7.1: Fig. 7.1: People People communicate communicate with the with the operating operating system through system through the user the user interfaceinterface oror shell by issuing shell by issuing commands.commands.

Applicationprogram

User interface

Operating system

Hardware

User

Interrupt Command

User Interface FunctionsUser Interface Functions

Identify userSpecify program to be executedSpecify peripheral device requirementsSupport run-time intervention

Types of User InterfacesTypes of User Interfaces

Command interfaceMenu interfaceGraphic user interfaceExpert system (voice-activated) interfaceWeb-form interface

Types of User InterfacesTypes of User Interfaces

Command Interface– Requires the user to type brief, cryptic commands.

MS-DOS Line Commands. Application program function-key commands.

– Require considerable user training.

Menu Interface– Presents the user with a list of available options.– Easier to learn and easier to use.– Traversing multiple menus can be time-consuming.

Types of User InterfacesTypes of User Interfaces

Graphic User Interface– Presents the user with a selection of windows, icons,

menus, and pointers. Macintosh Microsoft Windows

– Easy to understand, learn, and use– Consume considerable processor time and memory– Sometimes called an object-oriented interface or an

icon-based interface.

Types of User InterfacesTypes of User Interfaces

Expert System Interface– Voice-activated– Utilizes natural-language processing.

Voice recognition Voice data entry

– Requires a very powerful computer with a great deal of memory and a fast processor.

Types of User InterfacesTypes of User Interfaces

Web-Form Interface– Follows the metaphor established by the

Internet and the World Wide Web.

SummarySummary

Most modern operating systems incorporate Most modern operating systems incorporate these five componentsthese five components

User interface(shell)

Devicemanagement

Filemanagement

Memorymanagement

Processormanagement

Device ManagementDevice Management

Responsible for controlling communications with the system’s peripheral devices.

Interface Board

• Translates between internal and external form

Channel

• Performs peripheral device-independent functions on large computers

Device ManagementDevice Management

Responsible for controlling communications with the system’s peripheral devices.

Blocking Data

• Provides better utilization of disk/tape space

Most modern operating systems incorporate Most modern operating systems incorporate these five componentsthese five components

User interface(shell)

Devicemanagement

Filemanagement

Memorymanagement

Processormanagement

Processor ManagementProcessor Management

Efficiently managing the processor’s time. Machine Cycle

• ICU• ALU

Object Code – Machine language version of the source program

Concurrency – Multiple programs are loaded and

executed concurrently Interrupt – An electronic signal that causes the

system to save a link to the current program and start and operating system routine

Most modern operating systems incorporate Most modern operating systems incorporate these five componentsthese five components

User interface(shell)

Devicemanagement

Filemanagement

Memorymanagement

Processormanagement

File ManagementFile Management

Incorporates routines that allow the user or programmer to create, delete, modify, and manipulate files by name.

Logical Records• Programmer’s view of I/O

Physical Records• Input – Transferring data into memory from

a peripheral device• Output – Transferring data from memory to

a peripheral device Directory

• FAT - File Allocation Table• VTOC – Volume Table of Contents

File ManagementFile Management

Incorporates routines that allow the user or programmer to create, delete, modify, and manipulate files by name.

Access Techniques

• Sequential – Accessing data in physical order

• Random – Accessing data without regard for physical order

• Data Base Centralized Programmer can ignore physical data structure

Most modern operating systems incorporate Most modern operating systems incorporate these five componentsthese five components

User interface(shell)

Devicemanagement

Filemanagement

Memorymanagement

Processormanagement

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Data is stored in memory in Binary form Absolute Address – A physical location in

memory Relative Address

• An address relative to a base location• Allows a routine to be loaded into a different

location in memory

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Concurrency• Multiple programs are loaded into memory

and executed concurrentlyCache MemoryObject Code

Memory ManagementMemory Management Concerned with managing the system’s main

memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Resident Routines• A routine that stays in memory

Transient Routines• A routine that is loaded into memory as

neededTransient Area

• Memory for application programs and transient routines

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Fixed-Partition Management• Divides the Transient Area into fixed-length

partitionsDynamic Memory

• The Transient Area is treated as a pool of free space.

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Segmentation• Programs are divided into independently

addressed segments and stored in non-contiguous memory

Paging• Programs are divided into fixed-length pages

and loaded into noncontiguous memory

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Overlay Structures• Developed when the amount of available

memory was limited Virtual Memory

• Real Memory• External Paging Device• Virtual Memory

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Virtual Storage

• Uses an external device as an extension of real memory

Time Sharing

• Managing multiple concurrent users designed with interactive processing in mind

Memory ManagementMemory Management

Concerned with managing the system’s main memory resources as the computer runs, allocating space to applications as needed and ensuring that those applications do not interfere with each other.

Spooling

• Copying data from a slow input device to disk for subsequent processing