Question 1

What is an Operating System?

Accepted Answer

An Operating System (OS) is a specialized system software that acts as an intermediary or interface between a computer user and the computer hardware. Its primary goal is to provide an environment in which a user can execute programs in a convenient and efficient manner while managing the computer's resources.

Question 2

What are the main functions of an Operating System?

Accepted Answer

The main functions include process management (creation, scheduling, and deletion), memory management (tracking and allocation), file system management, device management through drivers, and providing security/protection. Additionally, it handles error detection, job accounting, and provides a platform for application software to run effectively without needing direct hardware access.

Question 3

What services are provided by an Operating System?

Accepted Answer

The OS provides essential services such as Program Execution (loading and running programs), I/O Operations management, File System Manipulation (reading/writing/creating files), Communications between processes, Error Detection (notifying users of hardware or software issues), Resource Allocation for multiple users, and Accounting to track resource usage patterns.

Question 4

What is the difference between 32-bit and 64-bit Operating Systems?

Accepted Answer

A 32-bit OS can handle a maximum of 2^32 memory addresses, limiting it to roughly 4GB of RAM, whereas a 64-bit OS can handle 2^64 addresses, allowing for massive memory capacities. 64-bit systems process more data per clock cycle and require 64-bit processors to function, offering significantly higher performance for modern computing tasks.

Question 5

What is a Kernel? Explain its role.

Accepted Answer

The Kernel is the central core of an operating system that manages all hardware and software operations. It acts as the primary interface between the hardware and the applications. Its roles include memory management, task scheduling, disk management, and managing I/O devices by acting as the first layer to load into memory.

Question 6

What is the difference between Kernel and OS?

Accepted Answer

The Kernel is just one specific part of the Operating System—specifically the 'core' that interacts directly with hardware. The Operating System is the complete package that includes the Kernel plus other components like system utilities, user interface shells, libraries, and application management tools required for a functional user experience.

Question 7

What is a Shell?

Accepted Answer

A Shell is a specialized program that serves as the interface between the user and the kernel. It takes commands from the user (via keyboard or GUI) and interprets them for the kernel to execute. Common examples include Bash in Linux and Command Prompt or PowerShell in Windows systems.

Question 8

What are System Calls? Give examples.

Accepted Answer

System Calls provide an interface between a running program and the operating system. They allow a user-level application to request services from the kernel, such as hardware access. Common examples include 'fork()' for process creation, 'read()' and 'write()' for file operations, and 'exec()' to load a new program.

Question 9

What is an API (Application Programming Interface)?

Accepted Answer

An API is a set of defined rules, protocols, and tools that allow different software applications to communicate with each other. In the context of OS, APIs like Win32 or POSIX provide a set of functions that programmers use to write applications that can interact with the underlying OS services without calling system calls directly.

Question 10

What is the difference between System Call and API?

Accepted Answer

A System Call is a low-level request made directly to the kernel for hardware-related services, whereas an API is a high-level set of functions that developers use in their code. Most APIs internally use system calls to perform the heavy lifting, but provide a more convenient and portable programming environment.

Question 11

What is the difference between RAM and ROM?

Accepted Answer

RAM (Random Access Memory) is volatile memory that stores data currently being used by the CPU but loses its contents when power is off. ROM (Read-Only Memory) is non-volatile and typically stores permanent instructions, like firmware or the BIOS, which remain intact even after the computer is turned off.

Question 12

What is the difference between SRAM and DRAM?

Accepted Answer

SRAM (Static RAM) uses flip-flops to store data and is faster but more expensive and less dense; it is typically used for CPU Cache. DRAM (Dynamic RAM) uses capacitors that must be refreshed constantly, making it slower but much cheaper and denser, which is why it is used for main system memory.

Question 13

What is the difference between PROM, EPROM, and EEPROM?

Accepted Answer

PROM can be programmed only once. EPROM can be erased using ultraviolet light and then reprogrammed. EEPROM (Electrically Erasable Programmable ROM) can be erased and reprogrammed electrically, making it the most modern and flexible of the three, commonly used in flash drives and modern computer BIOS/firmware storage.

Question 14

What is the role of BIOS?

Accepted Answer

BIOS (Basic Input/Output System) is firmware stored on a ROM chip that initializes the computer's hardware components during the startup process. Its primary role is to perform the Power-On Self-Test (POST) and locate the bootloader on the storage device to hand off control to the Operating System.

Question 15

What is the difference between BIOS and UEFI?

Accepted Answer

BIOS is an older 16-bit firmware with a text-based interface and limited disk support (MBR). UEFI (Unified Extensible Firmware Interface) is a modern 64-bit replacement that supports larger disks (GPT), faster boot times, mouse-driven graphical interfaces, and enhanced security features like 'Secure Boot' to prevent unauthorized code execution.

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