Post on 01-Jan-2016
description
CPU Main Memory User Interface Systems Software
Concepts Utility Programs
Input Devices
Processing(CPU/Memory)
OutputDevices
Storage Devices
• Also called CPU, processor or microprocessor
• “Brains” of the computer• Performs all computer
operations
• Where all the input data and results storedoRandom Access Memory (RAM)oRead Only Memory (ROM)
• RAM is volatile = data are lost when computer is turned off
• Read current info and also write new info• Very important in determining capabilities of the
computer system• Stores work when they are in use.
o Word Documento Spreadsheeto Power Point
• ROM is non-volatile = permanent and are not affected where computer is turned lost
• Can read info Stored in ROM
• Can not write new info into ROM
• Used for “internal workings” of computer– Boot Software
• A function of the operating system that allows individuals to access and command the computer
• Command-based User Interface• A particular user interface that requires text commands be
given to the computer to perform basic activities• E.g., unix, DOS
• Graphical User Interface (GUI)• A user interface that uses pictures (icons) and menus
displayed on the screen to send commands to the computer system
• Input Devices -> keyboard, mouse, monitor, touch-screen• Features of GUI -> Windows, Icons, Menus, Pointer
• Hardware Independences• Memory Management• Processing Tasks• Networking Capability• Access to System Resources
and Security• File Management
• Hardware independence– Operating system (OS) provides
hardware independence for application software
– Application software interfaces (API) with the operating system which interfaces with the hardware
• Memory management– Control how memory is accessed and
maximize available memory and storage
• Application Programming Interface (API)• A language and message format used by an
application program to communicate with the operating system or some other control program such as a database management system (DBMS) or communications protocol
Application Program Interface Links Application Software to
the Operating System
• Processing Tasks– Multitasking / Multiprogramming:
• More than one program in RAM at the same time
• Allows more than one active user program to be stored in main memory simultaneously
• Fairly sophisticated• All the jobs that enter the system are
kept in the job pool. This pool consists of all processes residing on mass storage awaiting allocation of main memory.
• If there is not enough room, then the system must choose among the jobs.
• A time-sharing system is a multiprogramming system.
• Processing Tasks– Time-Sharing
• Sharing of a computing resources among many users by means of multiprogramming
• Allowing a large number of users to interact concurrently with a single computer
• Dramatically lowered the cost of providing computing capability
• Made possible for individuals and organizations to use a computer without owning one
• Promoted the interactive use of computers and the development of new interactive applications
• Networking Capability– Features and capabilities of the OS
that aid users in connecting to a computer network
– Allow connected computers to:oCommunicateoShare resourcesoDivide work
• Access to system resources and security– Protection against unauthorized
access– Logins and passwords
• File management– Ensures that files in secondary
storage are available when needed and that they are protected from access by unauthorized users
• Help to perform maintenance or correct problems with a computer system.
• Designed to limited range of tasks• E.g. :
– Hardware utilities, – Virus-detection – Recovery utilities– File-compression utilities, – Spam and pop-up blocker utilities
• CPU is a ‘brain’ of a computer• Main Memory:
– RAM (volatile) & ROM (non-volatile)
• User Interface– Command-based User Interface– Graphical User Interface
• Systems Software Concept:– Hardware Independences– Memory Management– Processing Tasks– Networking Capability– Access to System Resources and Security– File Management