⚘ BY KAMESHWAR SAH⚘
UNIT
(1) INTRODUCTION TO OPERATING SYSTEM
(2) FILE SYSTEM(HDD)
(3) PROCESS/ MEMORY MANAGEMENT
(4) DEADLOCKS, SYNCHRONIZATION IPC
(5) ADV OPERATING SYSTEM
UNIT 1
Defination of operating system
Operating system are use to provide user programs with a batter simpler model of the computer to handel the management of all the system resources.
The computer has two most operation
The computer has two most operation
Program in kernal mode have acces to all the construction and resources where program running in user mode can only a sub set of instruction .
Type of operating system
(1) Mainframe operating system (2) Mobile operating system (3) Monolithic operating system (4) Modular operating system (5) Multiprogramming operating system (6) Distributed operating system (7) Real-time operating system (8) Embedded operating system (9) Personal operating system (10) Batch(job) operating system
System Boot:- BIOT(Basic Input Output System)
It is a program saved in flash memory on the paren board contains low-level instruction for input. It reads the keyboard, Writes to the screen and performs disk input/ output.
Step 1:-
When power is supplied BIOS is Activated.
Step 2:-
BIOS checks the amount of RAM installed.
Step 3:-
Bios check the presence of a keyboard and mouse.
Step 4:-
It scans ISA(Industry Standard Architecture) and PCI (Peripheral component interconnect), Buses to detect devices attached to them.
Step 5:-
These plug n play devices are recoded and if new devices are found then they are configured.
Step 6:-
BIOS determine boot devices by trying a list of devices stored in CMOS (complementary Mets Oxide Semiconductor).
Step 7:-
THE first sector from the boot device is transferred to memory and executed. This sector contains the boot loader.
Step 8:-
The boot loader examines the partition table at the end of the boot sector to determine which partition is active.
Step 9:-
The OS is read from the active portion by the boot loader.
Step 10:-
OS queries RIOS to get information about system configuration.
Step 11:-
For each attaches device OS checks to see the device drivers. If not to found it will ask the user to supply the driver.
Step 12:-
All the tables are initialized and background processes are processed is finally a login process is started through GUI or TUI.
BUFFERING (DATA BUFFER)
A data Buffer is the region of physical memory used to temporary store the data while it is being moved from one place to another typically th data B retriveed from an input devide or just before it is send to an output device . Buffer can be implemented in a fixed memory location in hardware or by using a virtual data Buffer in software.
Spooling
spooling stands for simultaneous peripheral operations online spooling is a specialized form of multiprogramming for the purpose of copying data between different devices in contemporary systems it is used for mediating between a computer application and a slow peripheral such as a printer, spooling allows programs to hand off the work to be done by the peripherals and then proceed to other tasks or do not begin until input has been completely received. A dedicated program called spooler maintains an orderly sequence of jobs for the peripheral and feed it data at its own rate.
System Call VS Funcation Call
one of the main functions of operating system is to provide instruction to user programs for this the operating system provides a series of application programmer interface (API) calls which programmers use. These APT's provider system calls which a user programmer uses to communicate with the operating system. A system call is the only entry point into the kernel system.
Types of System Calls:-
There are 5 categories of system calls
(1) System process control:-
Eg:- End process control, Abort, Create, Terminate, Associate, Free memory
(2) File management:-
Eg:- Create,Open, Close, Edit,Delete, Read file etc.
(3) Device Management:-
Eg:- Read and write
(4) Information maintenance:-
eg:- getoid(), alaram
(5) Communication:-
Eg:- pipe
UNIX VS WINDOWS/LINUX
POSIX(100 System Calls):-
100 System Call and Windows have 1000 system calls.
System calls in UNIX have one to one relationship with library procedure whereas system calls in Windows are highly decoupled from library procedure.
Windows can change system calls without changing the library procedure whereas in UNIX if we change system calls then we need to modify the library procedure also.
Comments