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Operating System
It is a layer of software and keeps track of all these components and use them correctly.
The function of an operating system is to…
Manages all the devices and provides user programs with a simpler interface to the software.
The Microarchitecture level consists of…
ALU
CPU
Machine Language Layer
Devoted to processing the machine languages.
Machine Languages
Are limited set of instruction that directly influence the working of physical device.
An Operating System runs in…
Kernel Mode
Application Programs runs in…
User Mode
The job of an Operating System is…
To provide for an orderly and controlled allocation of the processors, memories, and I/O devices among the various programs competing for them.
The Operating System’s primary task is to keep track of…
Who is using which resource?
Grant resource.
Account for usage.
Mediate conflicting requests.
Sharing of resource can be done in in two ways…
Time
Space
Time Multiplexed/Multiplexing
Users wait for their turn.
Space Multiplexed/Multiplexing
Each one gets part of the resource simultaneously.
Charles Babbage
The “First True Digital Computer” and the one who invented the Analytical Engine.
First Generation
Vacuum Tubes and Plug Boards
Second Generation
Transistors and Batch Systems
Batch System
Jobs were collected in a single room and then read onto a magnetic tape using in-expensive computers.
$JOB
Specifies the maximum run time in minutes, the account number to be charged, and the programmer’s name.
$FORTRAN
Tells the operating system to load the FORTRAN compiler from the system tape.
$LOAD
Directs the operating system to load the object program just compiled.
$RUN
Tells the operating system to run the program with the data following it.
$END
Marks the end of a job.
Third Generation
ICs and Multiprogramming
IBM 360
The first major computer line to use Integrated Circuits.
OS/360
Was developed with millions of lines of assembly language written by thousands of programmers.
Spooling
The ability to store jobs onto disk and do the processing on jobs and later store the processed job onto a disk.
Electricity Distribution System
When you need electric power, you just stick a plug in the wall, and within reason, as much power as you need will be there.
Ken Thompson
A computer scientist at Bell Labs who wrote a one-user version of MULTICS. Which later developed into UNIX.
POSIX
Defines a minimal system call interface that all UNIX systems must support.
MNIX
A small clone of UNIX, used for educational purposes.
Linus Torvalds
A Finnish student who developed Linux.
Fourth Generation
Personal Computers
Garry Kildall
Produced the first microcomputer.
Gary Kildall wrote a disk-based operating system called…
CP/M (Control Program for Microcomputers)
Bill Gates
He was the one who produced DOS (Disk Operating System).
Tim Patterson
Did some modifications to DOS and revised it to MS-DOS (Microsoft Disk Operating System).
Doug Engelbart
He was the one who invented the GUI (Graphical User Interface).
Steve Jobs
Co-invented Apple.
LISA
First GUI of Apple, which was very expensive and failed to sold in the markets.
Apple Macintosh
A user-friendly GUI of Apple which was much cheaper than LISA.
Windows
A GUI-based system which was influenced by Macintosh and a successor to MS-DOS.
UNIX
Is strongest on workstations and other high-end computers, such as network servers.
Linux
A popular alternative to Windows for students and increasingly many corporate users.
Network Operating System
Users are aware of the existence of multiple computers and can log in to remote machines and copy files from one machine to another.
Distributed Operating System
One that appears to its users as a traditional uniprocessor system, even though it is actually composed of multiple processors.
Mainframes
Are room-sized computers still found in major corporate data centers with high I/O capacity and high amount of data storage capacity.
Mainframe Batch Systems
One that processes routine jobs without any interactive user present.
Transaction Processing Systems
Handles large amount of small requests.
Timesharing Systems
Allow multiple remote users to run jobs on the computer at once.
Server Operating Systems
They serve multiple users at once over a network and allow the users to share hardware and software resources.
Multiprocessor Operating Systems
These are variations on the server operating systems, with special features for communication and connectivity.
The idea is to connect multiple CPUs into a single system in order to attain higher computing power.
Personal Computer Operating Systems
Their job is to provide a good interface to a single user. They are widely used for word processing, spread sheets, and internet access.
Real-Time Operating Systems
They focus on completing some job/process in an exact time in which the job has to be completed.
Hard Real-Time System
Are systems in which deadlines cannot be missed, if deadlines are missed it leads to catastrophy.
Soft Real-Time System
Missing an occasional deadline is acceptable.
Embedded Operating Systems
