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Transcript of OPERATING SYSTEM
Multiprogramming When one job needs to wait for I/O, the processor can switch to the other job
Time Sharing Using multiprogramming to handle multiple interactive jobs
Processor’s time is shared among multiple users
Multiple users simultaneously access the system through terminals First time-sharing system developed at MIT
Services Provided by the Operating System •Program development
–Editors and debuggers
•Access to I/O devices
•Controlled access to files
•Error detection and response
–Internal and external hardware errors
•Access forbidden memory locations
Popular Operating Systems DOS
Macintosh Operating System
Set of rules that tells the computer what operations to perform. Lower Level: Closer to form to the language the computer itself uses[1,0]
Higher Level: Closer to the language people use.
Education is what remains after one has forgotten everything he learned in school. A. Einstein Thank You Machine Language: Assembly language Jacquard loom
(1801) 11001100 00001111 00000011 11000011 Ada Lovelace
(1815-1852) AADDDD RR33,, RR11,, RR99 Evolution:
Requires a translator. Computers like ones and zeros…
Humans like symbols…
Assembler is a program that turns symbols intomachine instructions.
0001110010000110 ADD R6,R2,R6 high-level programming language Write program instructions called statement that resemble a limited version of English Statement: a= a + b
Distributed Systems - Loosely coupled systems that communicate via message passing. Advantages include resource sharing, speed up, reliability, communication.
Batch Processing Compiler vs. Interpreter spends some time evaluating the entire program and then translates all the programming statements of a program into a machine language program, which is then executed at once. Compiler translates interactively each programming statement into an immediately usable machine language instruction. Although an interpreter slows down the execution speed of a program somewhat, it does not require extra steps to compile and link like a compiler. Interpreter Process management Interrupts Memory management Device drivers Networking Security * RUNNING: The process that is currently being executed.
* READY: A process that is queuing and prepared to execute when given the opportunity.
* BLOCKED: A process that cannot execute until some event occurs, such as the completion of an I/O operation.
Hardware is expensive, humans are cheap Hardware is cheap, humans are expensive Hardware is very cheap, humans are very expensive acting as a translator between a hardware device and the applications or operating systems that use it. includes protection of information and property from theft, corruption, or natural disaster Machine languages (first-generation languages) are the most basic type of computer languages, consisting of strings of numbers the computer's hardware can use.
For example, IBM computers use different machine language than Apple computers Utility software Utility software is a kind of system software designed to help analyze, configure, optimize and maintain the computer. Disk defragmenters Disk space analyzers Disk partitions Backup Anti-virus Registry cleaners Network utilities Data compression artificial language Object Oriented Programming Data and operations are grouped together A Class is a user defined datatype which contains the variables, properties and methods in it. “Class” refers to a blueprint Object” is an instance of a class Each object has a class which defines its data and behavior Abstraction: Abstraction focuses on the essential characteristics of some object, relative to the perspective of the viewer. Encapsulation Encapsulation hides the details of the implementation of an object. Inheritance Inheritance is a way to compartmentalize and reuse code by creating collections of attributes and behaviors called objects which can be based on previously created objects Polymorphism An object is a thing.Think about object-oriented programming as a thing and something you want to do to that thing. Object What You Do with It
Your car Object What You Do with It
Fill it with gas
Your car Drive it
Fill it with gas
Database A database is any organized collection of data. Example: Why do we need a database: Keep records of our:
To keep a record of activities and interventions;
Keep sales records;
purpose of a database management system Is to transform
a spread sheet Relational databases Transaction Data Manipulation Language Language for accessing and manipulating the data organized by the appropriate data model
DML also known as query language
Data Definition Language Specification notation for defining the database schema
create table account( account_number char(10),
Behind the scene Database-Management System A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data Example: Data Dictionary A data dictionary contains metadata-that is, data about data. only a list of compositions arranged by composers
all works by a single composer
Object-Oriented Databases Consisting of objects that are linked to each other to reflect their relationships
Database Structure DBMS are designed to use specific data structure to provide end users quick and easy access to stored info. Five Fundamental Structure
Object oriented Structure
Multidimensional Structure Information is accessed from the top to the bottom Disadvantage – following the hierarchy is sometimes difficult, cumbersome, and time consuming.
to create and modify database objects used in an application schema committed: applied to the database
rolled back: undone from the database
an element can have one or more superiors relationships between the data can be established whenever the userrequest information Data Analysis and Mining Data Warehousing: A data warehouse is a repository (archive) of information gathered from multiple sources, stored under a unified schema, at a single site
Data Mining: Data Mining is used to discover patterns and relationships in data with an emphasis on large observational data bases
Microsoft Sql Server Oracle GENERAL APPLICATION SOFTWARE Simulation software Word Processing Programs Create text-based documents, reports, letters, and memos
Widely used in business, school, and home
Lotus Word Pro
Spreadsheets Organize, analyze, and graph numeric data
Widely used in many professions
Corel Quattro Pro
Database Software Organize related data for easy access
Database is a specially formatted file that contains data
Most popular DBMS
Presentation Graphics Create interesting, professional presentations
Combine visual objects, audio/video, text
Most Widely Used
Lotus Freelance Graphics
decision trees Real Time Processing: The ability of the operating system to provide a required level of service in a bounded response time.”
- POSIX Standard 1003.1
Hard: pacemakers Soft real-time systems: computer games Example: Weather Monitoring Multiprocessing: Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system Multimedia software Educational software Encyclopædia Britannica Ultimate Reference Suite Disney Interactive Studios Reader Rabbit Audio software Video editing software to present text, graphics, video, animation, and sound in an integrated way program that allows the user to observe an operation through simulation without actually performing that operation. Accounting software
Information worker software Allowed Character Check: email address: email@example.com consistency checks: if Mr., then M control Totals: add the total payments of a customer Data type checks: Numeric Data File Existence Check: specified name exits Format or Picture Check: DD/MM/YYYY Limit Check: data should not be greater than a number Logic check: input value should be 'o' Missing Data Test: Id number Range Check: Month 1-12 Uniqueness Check: Each value is Unique Alphabet 26 Validation