Operating System Tutorials

[Usr6]

Following are tutorials on different operating system concepts. Few of these tutorials are written by me, few are either gathered from various magazines/news papers or have been obtained from various Internet sources. The copyright of these tutorials belongs to their orginal publisher as the case may be. You can submit a tutorial on operating system. Your tutorial will be published here with your credentials. Submit your tutorial by sending it with an email to us.

Booting Process

The process and functions that a computer goes through when it first starts up, ending in the proper loading of the Operating System and preparing it to receive commands.

Writing Hello World Bootloader

Tutorial about creating a bootloader from scratch. Step by step tutorial with assembly code. Writing the bootloader to the floppy disk and booting the machine from this disk.

Programming Floppy Disk Controller

This tutorial describes the registers used to interface with the fdc controller, and the commands which it recognises. The Floppy Controller on a PC uses a standard configuration. On the XT there are 3 ports available for control and data access registers. On the AT, there are 4, and on the PS/2 there are 6.

Real mode

Real mode, also called real address mode, is an operating mode of 80286 and later x86-compatible CPUs. Real mode is characterized by a 20 bit segmented memory address space (meaning that a maximum of 1 MB of memory can be addressed), direct software access to BIOS routines and peripheral hardware, and no concept of memory protection or multitasking at the hardware level.

Protected mode

Protected mode on the 386 offers the programmer better protection and more memory than on the 286. The purpose of protected mode is not to protect your program. Learn about the difference between real mode and protected mode. How to enter into the protected mode.

CHS to LBA Translation

CHS translation is needed only for disk drives between 528MB and 8GB. Below 528MB CHS addresses do not require translation. Above 8GB CHS addressing is not supported by ATA hard disk drives or by system BIOS software. Most systems are finally making the switch to using LBA addressing on all capacity drives.

FAT File System

An introductory tutorial about DOS FAT File System. It explains the structure of Absolute Sector of the FAT, the addressing of logical sector. Read More..

Global Descriptor Table (GDT)

The Global Descriptor Table (GDT) defines base access privileges for certain parts of memory. We can use an entry in the GDT to generate segment violation exceptions that give the kernel an opportunity to end a process that is doing something it shouldn't. Most modern operating systems use a mode of memory called "Paging" to do this: It is alot more versatile and allows for higher flexibility.

Interrupt Descriptor Table (IDT)

The Interrupt Descriptor Table, or IDT, is used in order to show the processor what Interrupt Service Routine (ISR) to call to handle either an exception or an 'int' opcode (in assembly). IDT entries are also called by Interrupt Requests whenever a device has completed a request and needs to be serviced.

Segmentation

Segmentation is a Memory Management technique in which memory is divided into variable sized chunks which can be allocated to processes. Each chunk is called a segment. A table stores the information about all such segments and is called Global Descriptor Table (GDT). A GDT entry is called Global Descriptor.

Paging

Paging is another memory management technique which widely uses virtual memory concept. When paging is used, the processor divides the linear address space into fixed-size pages (of 4KBytes, 2 MBytes, or 4 MBytes in length) that can be mapped into physical memory and/or disk storage. When a program (or task) references a logical address in memory, the processor translates the address into a linear address and then uses its paging mechanism to translate the linear address into a corresponding physical address.

Partition Table

This is the tutorial about partition table. In this tutorial we will learn how the hard disk is divided into partitions. What are the primary partitions and what is the master boot record. We will also see the structure of the master boot record and the entry of each partition in MBR.

Graphical User Interface

Graphical user interfaces (GUIs) have become the user interface of choice. Yet despite the GUI's popularity, surprisingly few programs exhibit good interface design. Moreover, finding information explaining what constitutes a good and intuitive interface is exceedingly difficult. In this article, I describe the basic rules for all good interfaces -the cardinal dos and don'ts.

OS Glossary

Different terms related to operating system. GDT, LDT, CHS, LBA etc.

Makefile Tutorial

Write a makefile. Tutorial to make a makefile. Make is one of the original Unix tools for Software Engineering.By S.I. Feldman of AT&T Bell Labs circa 1975.