Operating Systems and Networks PDF Download – IT Series BSCS (5th Edition)

BSCS, MCS, and BSIT students can now download the complete IT Series textbook “A Comprehensive Study of Operating Systems & Networks” in PDF format. Written by Tariq Mahmood and Imran Saeed, and reviewed by Tasleem Mustafa, this 5th edition covers the full Operating Systems and Networks course taught at Pakistani universities across 16 chapters and 423 pages.

This book covers Operating Systems theory, Data Communications and Networks, and hands-on Windows 2000 Professional administration in a single volume. With more than 450 short questions, 300 MCQs, 200 true/false questions, and complete Windows and Linux coverage, it moves from core OS concepts in Chapters 1 to 12, into networking fundamentals in Chapter 13, and closes with practical Windows installation, user/file management, and network configuration in Chapters 14 to 16.

Book Overview

Program	BSCS, MCS, BSIT
Subject	Operating Systems and Networks
Series	IT Series
Edition	5th Edition
Authors	Tariq Mahmood, Imran Saeed
Reviewed by	Tasleem Mustafa
Publisher	IT Series
Total Chapters	16
Total Pages	423
Format	PDF (Free Download)

Chapter List

Chapter 1: Introduction to Operating System

Chapter 1 introduces the operating system as the software layer that manages hardware and mediates between users, application programs, and machine resources, tracing its evolution from batch systems and multiprogrammed mainframes through time-sharing to modern single-processor, multiprocessor, distributed, and clustered architectures. It distinguishes hard and soft real-time systems and explains interrupts, traps, and the dual user/kernel execution modes that protect the OS, closing with the OS’s core components and the system call interface through which programs request OS services.

Important Questions:

• What is the difference between symmetric and asymmetric multiprocessing? Symmetric multiprocessing treats all processors equally, while asymmetric multiprocessing has one master CPU that distributes tasks to slave processors.
• What is the difference between a hard real-time system and a soft real-time system? A hard real-time system guarantees a job completes within a specified time with bounded delays, while a soft real-time system does not guarantee this.
• What is the purpose of the mode bit in operating system design? It distinguishes between kernel mode and user mode execution, ensuring privileged instructions can only run in kernel mode.
• What is the difference between a trap and an interrupt? An interrupt is a hardware-generated change of flow, while a trap is a software-generated interrupt caused by an error or a system call.

Chapter 2: Process Management

Chapter 2 defines a process as a program in execution, covering its attributes, the five-state model (new, ready, running, waiting, terminated), and the Process Control Block that stores state, registers, and scheduling information. It details long-term, short-term, and medium-term schedulers, context switching, and process creation and termination, then covers inter-process communication through the shared-memory model and the message-passing model, including mailboxes and buffering.

Important Questions:

• What is the difference between a process and a program? A program is a passive entity specifying logic, while a process is an active entity that executes that logic and uses system resources.
• What are the five states a process can be in? New, ready, running, waiting, and terminated.
• What is the difference between the long-term scheduler and the short-term scheduler? The long-term scheduler loads jobs into memory and controls multiprogramming, while the short-term scheduler selects which ready process gets the CPU next.
• What is the difference between the shared memory model and the message passing model? Shared memory exchanges data through common memory and is faster, while message passing exchanges data via send/receive calls and is easier across a network.

Chapter 3: Threads

Chapter 3 defines a thread as a lightweight unit of CPU utilization within a process, contrasting kernel-level threads with user-level threads, and explains the many-to-one, one-to-one, and many-to-many multithreading models used to map user threads onto kernel threads. It also covers multithreading’s benefits, thread libraries such as POSIX Pthreads, Win32 threads, and Java threads, and Windows XP and Linux as examples.

Important Questions:

• What is the main difference between a process and a thread? A process is heavyweight with its own code, data, and heap, while a thread is lightweight and shares the process’s resources.
• What is the difference between user-level threads and kernel-level threads? User-level threads are managed by libraries in user space, while kernel-level threads are managed directly by the kernel.
• What is the many-to-many multithreading model? It multiplexes many user-level threads onto a smaller or equal number of kernel threads, allowing parallel execution on a multiprocessor system.
• Name three thread libraries commonly used today. POSIX Pthreads, Win32 threads, and Java threads.

Chapter 4: CPU Scheduling

Chapter 4 explains CPU scheduling as the mechanism for deciding which ready process gets the CPU, covering scheduling objectives, the CPU-I/O burst cycle, and preemptive versus non-preemptive scheduling. It works through major algorithms with worked examples, First Come First Served, Shortest Job First, Priority scheduling with aging, Round Robin, and Multilevel Queue scheduling, closing with multiple-processor scheduling and four ways to evaluate scheduling algorithms.

Important Questions:

• What is the difference between preemptive and non-preemptive scheduling? Non-preemptive scheduling only occurs when a process voluntarily leaves the CPU, while preemptive scheduling can forcibly remove a running process.
• What is aging in the context of priority scheduling? Gradually increasing the priority of a process the longer it waits, preventing starvation.
• What is a time quantum in Round Robin scheduling? The small fixed unit of CPU time given to each process in turn before it is preempted.
• What are the four ways to evaluate a CPU scheduling algorithm? Deterministic modeling, queuing models, simulation, and implementation.

Chapter 5: Process Synchronization

Chapter 5 addresses how cooperating processes that share data must be synchronized to avoid race conditions, defining the critical-section problem and its three required properties. It develops software solutions and the Bakery Algorithm, then introduces hardware instructions and semaphores, working through classic synchronization problems including producer-consumer, readers-writers, dining philosophers, and sleeping barber, and closes with monitors and condition variables.

Important Questions:

• What are the three requirements a correct solution to the critical-section problem must satisfy? Mutual exclusion, progress, and bounded waiting.
• What is a race condition? When several processes access shared data concurrently and the final result depends on the order of access.
• What is a semaphore and what are its two basic operations? An integer variable used for signaling, accessed through the atomic wait and signal operations.
• What is the main difference between a semaphore and a monitor? A semaphore is managed manually by the programmer, while a monitor bundles data and procedures with an automatically enforced lock.

Chapter 6: Deadlocks

Chapter 6 defines deadlock as a state where every process in a set is waiting for an event only another waiting process can trigger. It explains the four necessary conditions for deadlock, mutual exclusion, hold and wait, no preemption, and circular wait, and covers the resource-allocation graph, prevention strategies, avoidance through the Banker’s Algorithm, detection via wait-for graphs, and recovery through process termination or resource preemption.

Important Questions:

• What are the four necessary conditions for a deadlock to occur? Mutual exclusion, hold and wait, no preemption, and circular wait.
• Is it possible for a deadlock to involve only one process? No, deadlock requires a cycle of processes each waiting on another.
• What is the difference between deadlock prevention and deadlock avoidance? Prevention restricts requests so a necessary condition can never occur, while avoidance ensures the system never enters an unsafe state.
• What is starvation, and how does it differ from deadlock? Starvation is when a process is repeatedly denied resources even though the system keeps progressing overall, unlike deadlock where the system is stuck.

Chapter 7: Memory Management

Chapter 7 explains how the operating system shares main memory among processes, covering relocation, protection and sharing requirements, and address translation through absolute loading, relocatable loading, and dynamic loading and linking. It details memory allocation schemes including fixed and variable partitioning, first-fit, best-fit, and worst-fit placement, and introduces paging and segmentation, comparing the two and describing combined schemes.

Important Questions:

• What is the difference between internal and external fragmentation? Internal fragmentation is wasted space inside an allocated partition, while external fragmentation is free memory scattered in holes too small to use.
• What is the difference between first-fit, best-fit and worst-fit allocation? First-fit uses the first big-enough hole, best-fit uses the smallest suitable hole, and worst-fit uses the largest.
• What is dynamic loading and what advantage does it offer? A routine is only loaded into memory when actually called, so unused routines never occupy memory.
• What is a TLB and why is it used with paging? A translation look-aside buffer is a fast cache of page table entries that speeds up address translation.

Chapter 8: Virtual Memory

Chapter 8 covers virtual memory as a technique for running processes larger than physical memory, using demand paging so pages load only when referenced. It compares page-replacement algorithms including FIFO, Optimal, and LRU approximations, discusses frame allocation strategies, and explains thrashing, the working-set model, page-size trade-offs, and Belady’s anomaly.

Important Questions:

• What causes thrashing and how can it be reduced? A process is allocated fewer frames than it needs, forcing constant page faulting; it can be reduced by lowering the level of multiprogramming.
• What is Belady’s anomaly? For some algorithms like FIFO, increasing the number of available frames can actually increase page faults.
• How does the Optimal page-replacement algorithm work, and why is it not used in practice? It replaces the page not needed for the longest future time, but requires knowledge of future references, so it is impossible to implement.
• What is a working set? The set of pages a process has referenced during the preceding time interval, used to prevent thrashing.

Chapter 9: File System Management

Chapter 9 defines a file as a named collection of related information with attributes and operations like create, read, write, and delete. It covers sequential, direct, and indexed access methods, file protection through naming and access lists, secondary-storage allocation via contiguous blocks, linked blocks, and index blocks, reliability through periodic and incremental dumps, and directory structures from single-level to tree-structured and acyclic-graph directories.

Important Questions:

• What are the three main techniques for organizing file data in secondary storage? Contiguous blocks, block linkage, and index blocks.
• What is the difference between sequential access and direct access to a file? Sequential access processes records in order, while direct access lets a program read or write any block in any order.
• What does the UNIX permission string drwxrwxrwx represent? A directory with read, write, and execute permissions for owner, group, and other users.
• What is the difference between a periodic dump and an incremental dump? A periodic dump copies all files on a schedule, while an incremental dump copies only files changed since the last dump.

Chapter 10: I/O and Device Management

Chapter 10 covers how the I/O management module hides device complexity from users via virtual devices, explaining handshaking, polling versus interrupts, block versus character devices, and the storage hierarchy and caching. It also covers bus architectures, port versus memory-mapped I/O, busy-wait and interrupt I/O, DMA and cycle stealing, and software layers including sockets and device drivers.

Important Questions:

• How does the CPU read data from memory or an I/O device? It puts the address on the address bus, activates the proper control line, and waits until the target device places data on the data bus.
• What is Direct Memory Access (DMA) used for? It lets blocks of data move directly between memory and an I/O device without CPU involvement.
• What is cycle stealing? When a DMA device uses the system bus, forcing the CPU to stall for a cycle if it needs the bus at the same time.
• Why are hardware caches useful in I/O systems? They act as a buffer between components running at different speeds, so a fast device does not wait on a slower one.

Chapter 11: Operating System Security

Chapter 11 covers operating system security: the security problem, authentication methods, passwords and their vulnerabilities, encrypted and one-time passwords, and the prevention-detection-correction-identification cycle. It explains program threats like Trojan horses and trap doors, system threats like worms and viruses, and threat monitoring through audit logs and security scans.

Important Questions:

• What is the difference between a virus and a worm? A worm spreads copies of itself without user activation, while a virus attaches to a program and needs a human action to spread.
• How does encrypting stored data improve security? An intruder must defeat both the OS’s access controls and the password needed to decrypt the data.
• What problems can a computer virus cause? It can damage or erase files, disrupt normal system operation, and display unusual messages.
• How can a user notice if their password has been compromised? The system prints the last login time at logon, letting the user check for unauthorized access.

Chapter 12: Case Study: Linux

Chapter 12 is a practical case study of the Linux kernel, tracing its history and features and its major distributions like Red Hat, Slackware, SuSE, and Debian. It breaks the kernel into five subsystems: the process scheduler, the memory manager, the virtual file system, inter-process communication, and the network interface, layered over TCP/UDP/IP and network drivers.

Important Questions:

• Why is Linux considered portable and popular? It is written in C in a portable style, follows open standards, and supports many users running multiple tasks simultaneously.
• What role did the GNU Project and Free Software Foundation play in Linux? The Free Software Foundation sponsors the GNU Project, which developed many tools that became core parts of Linux.
• Why is the Linux file system described as hierarchical? The root directory sits at the top, with branches extending into subdirectories and files.
• What are the five major kernel subsystems in Linux’s architecture? The process scheduler, memory manager, virtual file system, network interface, and inter-process communication subsystem.

Chapter 13: Data Communication and Networks

Chapter 13 defines data communication as the electronic transfer of data via signals, covering the three transmission modes, simplex, half-duplex, and full-duplex, analog versus digital data, and the three modulation types. It explains computer networks and their criteria, client-server architecture, and the three main network categories, LAN, MAN, and WAN, along with wireless networks and all five topologies, bus, star, ring, tree, and mesh. The chapter closes with network standards bodies, protocol elements, and key technologies including Ethernet, Token Ring, TCP/IP, Bluetooth, Wi-Fi, WiMAX, and WAP, plus switched network types and dial-up versus dedicated telephone lines.

Important Questions:

• What are the three data transmission modes, and how do they differ? Simplex allows data in one direction only, half-duplex allows both directions but not at once, and full-duplex allows both directions simultaneously.
• What are the three key elements of a protocol? Syntax, the structure of the data; semantics, the meaning of each section; and timing, when data should be sent and how fast.
• What is the main difference between LAN and WAN? LAN connects computers in one place at high speed and low cost, while WAN connects computers across cities or countries at lower speed and higher cost.
• What is the key difference between Bluetooth and Wi-Fi? Bluetooth connects up to 7 devices within about 30 feet with low power and more security, while Wi-Fi covers 300 to 500 feet and needs more configuration and power.

Chapter 14: Windows 2000 Professional: Installation & Configuration

Chapter 14 covers Windows 2000 Professional installation and configuration in detail. It explains hardware requirements, disk partitioning, and the file systems supported, FAT, FAT32, NTFS, and CDFS, comparing their security and reliability. It walks through the CD-ROM installation process and network-based installation, then covers desktop customization, Control Panel, Computer Management, accessibility features, and installing and configuring printers and network hardware.

Important Questions:

• Which file systems does Windows 2000 Professional support, and when would each be used? FAT, FAT32, and NTFS; FAT/FAT32 suit dual-boot setups, while NTFS is better when only Windows 2000 is installed, since it offers file and folder security.
• What are the two ways to start the Windows 2000 setup installation program? Booting directly from the Windows 2000 CD, or booting from four setup floppy diskettes when the system cannot auto-boot from CD.
• What steps happen during the text-based phase versus the graphics-based phase of installation? Selecting a partition and file system happens during the text-based phase; entering organization details and network components happens during the graphics-based phase.
• What is the main advantage of plug-and-play hardware in Windows 2000? The operating system automatically detects it and installs the appropriate driver without manual configuration.

Chapter 15: Managing Users, Files and Folders

Chapter 15 explains how Windows 2000 Professional manages users, files, and folders. It covers local, domain, and built-in account types, creating and managing accounts through Computer Management, local and built-in groups, auditing, password and account lockout policies, and user profiles including local, roaming, and mandatory profiles. It also covers organizing, sharing, and setting permissions on files and folders, plus NTFS security features.

Important Questions:

• What is the main advantage of a domain user account over a local user account? A domain account can be used to log on anywhere in the domain, while a local account only works on the computer where it was created.
• What are the built-in user accounts in Windows 2000, and what are their key features? Administrator, which has no restrictions, and Guest, which gives limited access and is disabled by default.
• What are the main advantages of NTFS security for files and folders? It protects against unauthorized access and accidental damage, works locally and over the network, and allows auditing.
• What is the difference between the Read and Execute permission and the List Folder Contents permission? List Folder Contents only lets a user view what is in a folder, while Read and Execute also allows reading files and running programs.

Chapter 16: Network Protocols, Connectivity and Backup

The book’s final chapter covers configuring TCP/IP with either a static IP address or DHCP, and testing the configuration using the ipconfig and ping utilities. It explains dial-up networking, including modem setup through Device Manager and the connection wizard, and closes with the Windows Backup utility, its five backup types, and the procedure for backing up and restoring files and folders.

Important Questions:

• What is the difference between a static IP address configuration and a DHCP-based configuration? A static IP is entered manually, while DHCP assigns configuration automatically from a server.
• What are ipconfig and ping used for when testing TCP/IP configuration? ipconfig verifies TCP/IP configuration on a host, while ping tests connectivity to another host.
• What are the five types of backup supported by Windows Backup, and how does Normal differ from Incremental? Normal, Copy, Incremental, Differential, and Daily; Normal backs up all selected files, while Incremental only backs up files changed since the last backup.
• What information must be entered when creating a dial-up connection? The telephone number to dial, the connection availability, and a name for the connection.

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Who Should Read This

This book is written for BSCS, MCS, and BSIT students studying Operating Systems and Networks at Pakistani universities. It is suitable for both OS-only courses and combined OS and Networks courses, and its Windows 2000 chapters make it useful for practical system administration labs too. Students preparing for university exams, viva, or who need a comprehensive reference for OS concepts and networking fundamentals will find this book very helpful.

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Applicable Universities

This IT Series textbook is widely used at Pakistani universities offering BSCS, MCS, BSIT, and MS-CS programs including Punjab University, Virtual University, COMSATS, FAST, UET, and other HEC-recognized institutions.

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