Revision Lecture Note for Operating System
Dr Aliyu Ahmed
August 5, 2024
Introduction to Operating Systems
Definition and Purpose
• Operating System (OS): A software that acts as an intermediary be-
tween computer hardware and users. It manages hardware resources and
provides services for computer programs.
• Primary Goals: Efficient resource management and user convenience.
Types of Operating Systems
• Single-User Systems: Designed for one user at a time (e.g., personal
computers).
• Multi-User Systems: Allow multiple users to use the computer simul-
taneously (e.g., servers).
• Real-Time Systems: Provide immediate processing and responses (e.g.,
embedded systems).
Historical Background
Evolution of Operating Systems
• First Generation (1940s-1950s): Vacuum tubes, no operating systems.
• Second Generation (1950s-1960s): Transistors, batch processing sys-
tems.
• Third Generation (1960s-1970s): Integrated circuits, multiprogram-
ming, and time-sharing systems.
• Fourth Generation (1970s-Present): Personal computers, graphical
user interfaces, networked and distributed systems.
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, Notable Operating Systems
• UNIX (1969): Developed at Bell Labs, multi-user and multitasking ca-
pabilities.
• MS-DOS (1981): Microsoft Disk Operating System for personal com-
puters.
• Windows (1985): Microsoft’s graphical operating system.
Operating System Architecture
Kernel
• Definition: The core component of the OS, managing system resources
and communication between hardware and software.
• Types:
– Monolithic Kernels: All OS services run in kernel space.
– Microkernels: Only essential services run in kernel space; others
run in user space.
User Space
• Definition: Area where application software and some OS services run,
isolated from kernel space.
Processes
Definition and Lifecycle
• Process: A program in execution, including its current activity, state,
and allocated resources.
• Lifecycle States: New, Ready, Running, Waiting, Terminated.
Process Control Block (PCB)
• Definition: Data structure containing information about a process, such
as PID, state, CPU registers, memory allocation, and I/O status.
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Dr Aliyu Ahmed
August 5, 2024
Introduction to Operating Systems
Definition and Purpose
• Operating System (OS): A software that acts as an intermediary be-
tween computer hardware and users. It manages hardware resources and
provides services for computer programs.
• Primary Goals: Efficient resource management and user convenience.
Types of Operating Systems
• Single-User Systems: Designed for one user at a time (e.g., personal
computers).
• Multi-User Systems: Allow multiple users to use the computer simul-
taneously (e.g., servers).
• Real-Time Systems: Provide immediate processing and responses (e.g.,
embedded systems).
Historical Background
Evolution of Operating Systems
• First Generation (1940s-1950s): Vacuum tubes, no operating systems.
• Second Generation (1950s-1960s): Transistors, batch processing sys-
tems.
• Third Generation (1960s-1970s): Integrated circuits, multiprogram-
ming, and time-sharing systems.
• Fourth Generation (1970s-Present): Personal computers, graphical
user interfaces, networked and distributed systems.
1
, Notable Operating Systems
• UNIX (1969): Developed at Bell Labs, multi-user and multitasking ca-
pabilities.
• MS-DOS (1981): Microsoft Disk Operating System for personal com-
puters.
• Windows (1985): Microsoft’s graphical operating system.
Operating System Architecture
Kernel
• Definition: The core component of the OS, managing system resources
and communication between hardware and software.
• Types:
– Monolithic Kernels: All OS services run in kernel space.
– Microkernels: Only essential services run in kernel space; others
run in user space.
User Space
• Definition: Area where application software and some OS services run,
isolated from kernel space.
Processes
Definition and Lifecycle
• Process: A program in execution, including its current activity, state,
and allocated resources.
• Lifecycle States: New, Ready, Running, Waiting, Terminated.
Process Control Block (PCB)
• Definition: Data structure containing information about a process, such
as PID, state, CPU registers, memory allocation, and I/O status.
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