Interface between hardware and user; an OS is responsible for the management and coordination of activities and the sharing of the resources of the computer.
It manages the hardware and software resources of the system. In a desktop computer, these resources include such things as the processor, memory, disk space and more (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the network connection).
It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.
Users Application Software Operating and systems software Hardware Dilfaroz A Khan
Throughput: Total number of jobs completed divided by The total time required to complete the job. For example JOB1 and JOB2 takes 5 minutes each for execution the throughput is 2jobs divided by 10 minutes i.e. 0.2 job/minute
In the above scheduling a schedule job always completes before another schedule job is taken. In other words jobs finish in the order in which they are scheduled. In other words resources can not be taken away.
In this kind of scheduling decision can be made while the job is executing. In other words resources can be taken away.
A contemporary computer system includes a wide assortment of “IP/OP” devices called peripheral devices such as printers, card readers, magnetic tapes etc.. A large installation may out half of the system cost in peripherals so it may be used in a efficient manner.
The operating system provides convenient ways for storing and retrieving the information from files.
A file is a collection of related information. Every file has a name, data and attributes. Name of a file is unique. The attributes have information date and time, last access date , size, location etc…
The file management part of OS takes care of file related activities such as structuring, accessing, naming, sharing, protecting etc..
Process of starting up any computer and loading the OS in memory.
Power is on
Once a 'Power Good' signal is sent to the motherboard, the CPU looks for the ROM bios.
The CPU looks to the ROM bios for the first instruction, and the first instruction is to run the POST (Power-On-Self-Test).
POST checks the CPU, hardware devices such as the Video Card, the secondary storage devices such as the Hard Drive, Floppy Drives, Zip Drive or CD/DVD Drives.
If there are any errors found then an error message is displayed on screen or a number of beeps are heard.
Next the bios finds the video card and runs the video card's bios.
The bios then displays the system configuration.
During the display more tests are conducted including the test that shows your computer testing the memory. If there are any problems found from now on they will be displayed in a text message on the screen.
After that the bios searches for something that it can boot from i.e hard disk drive
After activating it , it finds the first piece of OS i.e. BOOTSTRAP LOADER
Bootstrap loader loads the OS into memory and allows it to begin operation
Then it turns controls of the computer over to the OS
Linux: Version (flavor) of UNIX available without charge over the Internet
Increasingly being used with PCs, servers, mainframes, and supercomputers
Is open-source software: has been collaboratively modified by volunteer programmers all over the world
Originally used a command line interface, most recent versions use a GUI
Strong support from mainstream companies, such as Sun, IBM, HP, and Novell
Used on PCs, mainframes, and consumer appliances
Growing integration between Linux and other operating systems is a recent development
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Comparison GUI and CUI Dilfaroz A Khan GUI CUI Symbols, pictures and pointing commands are use to execute commands Set of characters and words are used to execute the commands No need to remember the command. A small practice enables you to use the commands The syntax and various options are required to be remembered. General menu structure and commands are used for all the applications. Different application have their own set of commands. Number of applications can be opened and executed in different window at the same time Only one application can run at a time Minimum use of keyboard Maximum use of keyboard Mouse extensively used Mouse used only in some applications Easy to operate Not user friendly hence difficult to operate
It is a name given to the interleaved execution of two or more different and
independent programs by the same computer.
It places two or more user programs in the main memory and executes them
When one program is waiting for IO transfer there is another program ready
to utilize the CPU, thus it is possible for several user to share the time of
2. Multi processing: - it is used to describe a system where by two or more interconnected CPU’s perform several simultaneously. - It is also called Parallel Processing. - the CPU is capable of executing different instructions from the same program at the same time. - Assigning different jobs to CPU’s is possible. Dilfaroz A Khan
Key words. 3. Multitasking : - is the name given to the concurrent execution of two or more user tasks by the same computer. - It place two or more task in the main memory and concurrently executes them Dilfaroz A Khan