Презентация на тему Operating Systems

makes a computer to actually work.

It is the software

the enables all the programs we use.

The OS organizes and controls the hardware.

OS acts as an interface between the application programs and the machine hardware.

Examples: Windows, Linux, Unix and Mac OS, etc.,

basic tasks such as,

controlling and allocating memory,
prioritizing

system requests,
controlling input and output devices,
facilitating networking and
managing file systems.

consists of 4 layers:
Hardware
Hardware consists of

CPU, Main memory, I/O Devices, etc,

Software (Operating System)
Software includes process management routines, memory management routines, I/O control routines, file management routines.

consists of compilers, Assemblers, linker etc.

Application programs
This

is dependent on users need. Ex. Railway reservation system, Bank database management etc.,

through seven major phases.

Six of them significantly changed

the ways in which users accessed computers through the open shop, batch processing, multiprogramming, timesharing, personal computing, and distributed systems.

In the seventh phase the foundations of concurrent programming were developed and demonstrated in model operating systems.

batch (BATCH- a set of jobs with similar needs)

together and execute at a time.
The OS was simple, its major task was to transfer control from one job to the next.
The job was submitted to the computer operator in form of punch cards. At some later time the output appeared.
The OS was always resident in memory. (Ref. Fig. next slide)
Common Input devices were card readers and tape drives.

tape drives, and card punches.
Users did not interact directly

with the computer systems, but he prepared a job (comprising of the program, the data, & some control information).

OS

User program area

programs simultaneously by a single processor.
In Multiprogramming, number of

processes reside in main memory at a time.
The OS picks and begins to executes one of the jobs in the main memory.
If any I/O wait happened in a process, then CPU switches from that job to another job.
Hence CPU in not idle at any time.

system.
The main memory consists of 5 jobs at

a time, the CPU executes one by one.
Advantages:
Efficient memory utilization
Throughput increases
CPU is never idle, so performance increases.

logical extension of multiprogramming.
Multiple jobs are executed by switching

the CPU between them.
In this, the CPU time is shared by different processes, so it is called as “Time sharing Systems”.
Time slice is defined by the OS, for sharing CPU time between processes.
Examples: Multics, Unix, etc.,

are:

Program creation
Program execution
Input/Output operations
Error detection
Resource allocation
Accounting
protection

as,-

Single User Systems

Multi User Systems

one user at a time.

They are popularly associated

with Desk Top operating system which run on standalone systems where no user accounts are required.
Example: DOS