History of Disk Operating System-Topic
With the production of first personal computer by MITS, MEXIC in 1975, which used 8-bit Intel 8080 CPU and had a memory of 256 bytes, began the revolution in the PC, market. This PC was called Altair. Bill gates wrote a program in BASIC for his PC to make it work; it was this program which made Bill Gates a billionaire.
Within next five years, more and more companies started manufacturing these P.C. which were based on 8080 Intel chip. Almost every PC was working with on Operating System
, produced by Digital Research Co., ofCalifornia.
This operating system used by these personal computers (also known as Micro Computers) was known as CP/M. The PC was used basically for entertainment purposes.
IBM, which in 1980s dominated the computer industry made plans to make the P.C. manufacturing its area and started developing its own personal computers. The problem was, if it starts from the scratch to Manufacture the PC, it would take long time therefore it decided to assemble various components manufactured by other manufactures and make a P.C. Intel has already launched its newer versions of the chip i.e., 16-bit 8086 and 8088. IBM chooses 8088 as its chip, IBM, as it was concentrating on hardware was not at all interested in software. Therefore it approached Bill Gates, who has started his company, the Microsoft, to use the BASIC interpreter, which he designed for their P.C.s and even for an operating system if possible.
As Microsoft was selling AT & T UNIX, which needed about 100k memory for operating system itself and also a hard disk and the IBMs machine has altogether 64k of memory and mo hard disk. Bill gates referred them to use Digital Research’s CP/M-86 Operating System. When IBM approached Digital Research, it said that it would take long time for CP/M-86 as it was behind schedule.
As IBM could not wait, it re-approached Bill Gates to write an operating system, similar to the CP/M, then Bill Gates to save time; he bought an operating system known as 86-DOS which was the product of Seattle computer products, which was used to test memory boards manufactured by it. He also hired Tim Paterson, the author of 86-DOS and it as upgraded and renamed as MS-DOS (Micro Soft-Disk Operating System). Thus MS-DOS had its birth. This operating System was given to IBM as an operating system, and then IBM came with PCs which has MS-DOS as Operating System.
The Basic Virtue of the MS-DOS
are perceived by IBM and other companies was that the MS-DOS was capable of running almost every software which was running on CP/M with 8080 chip with as little changes a possible. This happened in August 1981. The MS-DOS version which was released with IBM-PCs was known as version 1.0. The memory occupied by it was as low as 12k. It supported 5.1 inch diskette with 160k of capacity.
MS-DOS version 1.0
These operating systems had about 4000 lines of code. This system consisted of three programs which are as follows:
Ibm bio.com: For disk and character I/O system.
Ibm dos.com: For disk and file management.
Command.com: The command interpreter.
This version supported only single directory. This system has capacity handle batch files. Later came the version 1.1 which fixed the bugs (errors) in version 1.0 subsequently came the version 2.0 of MS-DOS which is totally a New Operating System. Later came versions 3.0, 4.0, 5.0, 6.0 etc., with more and more advanced features and added utilities.
Features of MS-DOS (Microsoft Disk Operating System)
Apart from the file ibm bio.com, ibm dos.com, command.com two other programs which are quite important part of MS-DOS are:
Config.dyd: Which is used to configure the system?
Autoexec.bat: This file contains the list of commands which are to be executed when the system is started i.e., booted.
Let us look at the terminology which is used by MS-DOS.
Program: Program is basically a combination of set of various instructions which are written using Computer Languages(we are learning, about these languages in details in following chapters). These instructions are used to make to computer know the tasks which it has to perform.
File: File is collection of records, which are logically related. These are quite similar to manual files which we maintain to hold mails, memos etc, and MS-DOS supports following types of files:
Text Files: These are the files which are used to store data. The data can be in the form of characters, numbers and any other symbols. These are the files which are used to store input as well as output of the programs. These files are also known as data files as they are used to store data.
Batch Files: These are the files which contain set of instructions, which are to be executed as a batch in a sequential order. These files are usually used to perform a specific task.
Application Program Files: These are the files which usually as application specific. They are used to do perform specific tasks which will enable a user to do his job easily. Word Processors
, calculations, spread sheets etc are some of the Application Program Files.
Character of a File: Any file has certain characteristics which are used to work with the file. Some of the important characteristics of a file are:
File Name: It is the name with which the file is identified. It is used to distinguish between two files. A file name can be at most eight characters long, which can be either in upper files. A file name can be at most eight characters, numbers or some special characters also. By default, the MS-DOS converts the file names to uppercase automatically.
File extensions can be used as suffix to identify the file type. MS-DOS permits three character extensions; some commonly used extensions are .exe, .bat, .doc, .txt, .dat etc. Hello, Matter, Demo.txt, abc.exe, fine.bat etc, are valid files names.
Education of Directory – Computing
We usually feel and have a need to store all the related files at one place so that our search for a specific file becomes easier. For this reason, the concept of the Directory has emerged. Directory is logical grouping of files. A directory contains the names of the files it holds, along with their extension, the file size, the data of creation or the data of last modification. We can look at directory structure which is inverted tree which has one directory at the top level or highest level which is known as “root” directory, which is the Home directory for all the directories. Usually the directory happens to be the drive representation like C :>, D :>, E:>, A:>, B:>, and so on.
We usually use these directories to store related files, therefore we create directories and usually it is advisable to work in directories other than the Root/Home directory. The directory in which one is currently working is known as Current directory.
Path: The location of directory with respect to the other directory has to be clearly stated if we are working under some other directory. The path can be represented by two methods. One giving the total path starting from the root directory, which is known as Absolute path.
The other way is to give a path with respect to the current directory; this is known as relative path. Let us look at the following Directory Structure and understand the absolute and relative path:
Absolute Path: For absolute path, we start from the root i.e. VIBGYOR, descendant directories separated by slash ‘’.
Relative Path: to understand the relative path, we need to know the following notation:
Current Directory is denoted by “.” [Dot]
Parent Directory is denoted by “.” (2 Dot]
Let is look at the relative path of “INDIGO”. Let us assume that we are at “WHITE” i.e., current directory is WHITE, now let us look at the relative path of “INDIGO” w.r.t. WHITE is
The first dot represent white i.e., the current directory, next two dots take to the parent directory of white i.e., “GREEN”, next two dot take to the parent directory i.e., “VIBGYOR” then the path takes to “INDIGO”.
The relative path sometimes will be very easy to use when the Destination Directory is near to the current directory.