Operating System

 

Operating System

An Operating System(OS) is a system software that manages computer hardware, software resources, and provides common services for computer programs. An operating system is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer. 

Types of Operating Systems

a. Batch Operating System: A set of similar are stored in the main memory for execution. A job gets assigned to the CPU, only when the execution of the previous job completes.

b. Multiprogramming Operating System: The main memory consists of jobs waiting for CPU time. The OS selects one of the processes and assigns it to the CPU. Whenever the executing process needs to wait for any other operation(like I/O), the OS selects another process from the job queue and assigns it to the CPU. This way, the CPU is never kept idle and the user gets the flavor of getting multiple tasks done at once. 

c. Multitasking Operating System: Multitasking OS combines the benefits of Multiprogramming OS and CPU scheduling to perform quick switches between jobs. The switch is so quick that the user  can interact with each program as it runs.

d. Time Sharing Operating System: Time-Sharing systems require interaction with the user to instructs the OS to perform various tasks. The OS responds with an output. The instructions are usually given through an input device like the keyboard.

e. Real Time Operating System: Real-Time OS are usually built for dedicated systems to accomplish a specific set of tasks within deadlines.

Function of Operating System(OS)

a. Process management: The OS manages and control processes, which are executing instance of programs. It schedule processes, allocate resources, and provides mechanism for process communication and synchronization.

b. Memory management: The OS allocate and tracks system memory to processes, ensuring efficient memory utilization. It handles memory allocation, deallocation and swapping processes it and out of memory when needed.

c. File system management: The OS provide a hierarchical structure for organizing and storing files on secondary storage device. It manages file operation, such as creation, deletion, reading and writing and ensures data integrity and security.

d. Device management: The OS interacts with and manages various hardware device, such as input/output devices, storage devices and network interface. It provides drivers and handles device operations, including device allocation, scheduling and error handling.

e. User interface: The OS provides a user interface through which user interacts with the company system. This can be a command-line interface, graphical user interface(GUI), or a combination of both allowing users to run programs, manages files and configure system setting.

Difference between Internal DOS Command & External DOS Command

Internal DOS Command	External DOS Command
These commands are contained in files of MS DOS.	These commands are not in-built in MS DOS.
Functions of Internal DOS Commands are built into the command interpreter.	Functions which are not included in the interpreter.
Requires any external file in the computer to read Internal DOS Command.	Requires an internal file in the computer to read external DOS Command.
An internal command is embedded into the command.com file.	An external command is not and requires a separate file to operate.

Difference Between RISC and CISC Architecture

RISC	CISC
It is a Reduced Instruction Set Computer	It is a Complex Instruction Set Computer
Emphasis on software	Emphasis on hardware
Instructions of same set with few formats	Multiple instruction sizes and formats
Uses more registers	Less registers
Fewer addressing mode	More addressing mode
Instructions take one cycle time	Instructions take a varying amount of cycle time
Pipelining is easy	Pipelining is difficult

Graphical User Interface(GUI)

In computing, GUI (Graphical User Interface) is a type of interface that allows the user to interact with electronic devices through graphical icons and visual indicators. GUI is opposed to text-based, interfaced, typed command.

Some examples of GUI based Operating System

• Microsoft Windows
• Linux
• Android
• Apple iOS
• Mac OS

Operating System