The document provides an overview of operating systems, discussing their functions, structures, operations, and types such as open-source systems. It details various operating system structures, including simple, layered, microkernel, and modular architectures, along with debugging methods like log files and core dumps. Additionally, the document outlines system programs and the system boot process, emphasizing their roles in managing and executing system software.

1. Operating Systems
UNIT – I
Dr.B.Srinivas 7/17/2024

2. UNIT I
Operating Systems Overview: Operating system
functions , Operating system structure, Operating
systems operations, Computing environments, Open-
Source Operating Systems.
System Structures: Operating System Services, User
and Operating-System Interface, systems calls, Types
of System Calls, system programs, operating system
structure, operating system debugging, System Boot.
Operating Systems
Dr.B.Srinivas 7/17/2024

3. Operating- System Structure
 Simple Structure
 Layered Structure
 Micro kernel Structure
 Modules Structure
Dr.B.Srinivas 7/17/2024

4. Simple Structure
 MS-DOS – written to provide the most
functionality in the least space
Dr.B.Srinivas 7/17/2024

5. Layered Structure
 The UNIX OS consists of two separable parts
Systems programs
The kernel
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6. Micro kernel Structure
 The user services and kernel services are
implemented in different address space.
 It reduces the size of kernel and size of operating
system as well.
e.g:-Mac OS, MS-Windows
Dr.B.Srinivas 7/17/2024

7. Modules Structure
 Most modern operating systems implement kernel
modules
 Uses object-oriented approach
 Each core component is separate
Eg:- Solaris
Dr.B.Srinivas 7/17/2024

8. Operating System Debugging
Debugging is the process of finding the problems in
a computer system and solving them. There are
many different ways in which operating systems
perform debugging.
 Log Files
 Core Dump Files
 Crash Dump Files
 Trace Listings
 Profiling
Dr.B.Srinivas 7/17/2024

9. Log Files
The log files record all the events that occur in an
operating system.
 Event Logs These stores the records of all the
events that occur in the execution of a system.
 Transaction Logs store the changes to the data so
that the system can recover from crashes and other
errors.
 Message Logs These logs store both the public and
private messages between the users. They are mostly
plain text files, but in some cases they may be HTML
files.
Dr.B.Srinivas 7/17/2024

10.  Core Dump Files
The core dump files contain the memory address
space of a process that terminates unexpectedly.
 Crash Dump Files
In the event of a total system failure, the
information about the state of the operating
system is captured in crash dump files.
 Trace Listings
The trace listing record information about a
program execution using logging. This information
is used by programmers for debugging.
 Profiling
Profiling is done by monitoring the source code of
the required system program using a code
profiler.
Dr.B.Srinivas 7/17/2024

11. System Programs in Operating System
Dr.B.Srinivas
 System Programming can be defined as the act of
building Systems Software using System
Programming Languages.
 Program Development and Execution can be done
conveniently in System Programs.
 It traditionally lies between the user interface and
system calls.
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12. Dr.B.Srinivas
 System Programs can be divided into these
categories :
1. File Management
2. Status Information
3. File Modification
4. Programming-Language support
5. Program Loading and Execution
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13. System Boot
Booting the system is done by loading the kernel
into main memory, and starting its execution.
Dr.B.Srinivas 7/17/2024