Types of Commands

DOS Commands are two types

1) Internal Commands.

2) External Commands.

INTERNAL COMMANDS:

The internal commands are those which are automatically loaded in the memory of your personal computer when DOS is loaded. Then those commands can be used without the need of any file or diskette. The internal commands are simple and are used for common jobs, such as copying, erasing and renaming file or changing the directory and changing the current date, time in your personal computer.

All internal commands are called memory resident commands.

All internal commands are part of Command.com

These are do not require any special files for being executing and are brought into the memory as soon as the computer is switched on.

List of Internal Commands :

DIR	CD
COPY	MD
DEL	CLS
TYPE	DATE
TIME	PATH
REN	RD1
BREAK	CALL
ECHO	EXIT
GOTO	IF
PAUSE	PROMPT
REM	SET
SHIFT	VER
VERIFY	VOL

EXTERNAL COMMANDS:

The external commands are used for relative complex jobs such as copying the entire diskette, comparing or joining files, sorting text and formatting a diskette. For using external commands, you need to use corresponding file available in the DOS diskettes or the hard disk.

All External commands are disk  resident commands. These commands will be loaded at the use of request.

Any command which contains COM, EXE, BAT may called as external commands.

These are require certain special DOS files for being executed.

List of External Commands :

FORMAT	ATTRIB
CHKDSK	TREE
XCOPY	DISKCOPY
PRINT	SWISS
BACKUP	GRAPHICS
CHKDSK	LABLE
DISK.COM	MODE
DELTREE	MORE
UNFORMAT	FDISK
SORT	UNDELATE
DOS-KEY	MOVE
EDIT	SCANDISK

Various DOS Command List :

List of Directory Commands :

DIR	MD
RD	TREE
PATH	SUBST

List of File Management Commands :

COPY	XCOPY
DEL	RENAME
ATTIB	BACKUP
RESTORE	FIND
SYS	COPYCON
EDIT

List of File Disk Management Commands :

FORMAT	CHKDSK
DISKCOPY	LABLE
VOL	DISKCOMP
COMP	RECOVER

List of File General Commands :

TYPE	DATE
TIME	PROMPT

List of Batch File Commands :

CALL	CHOICE
@	IF
FOR	GOTO
PAUSE	REM
SET	SHIFT

List of DOS Utility File Commands :

MEMMAKER	MSAV
DBLSPACE	MOVE
DEFRAG	DELTREE
MSBACKUP	SCANDISK
SETVER	UNDELETE
UNFORMAT	XCOPY

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What is Operating System and Types of Operating System

An operating system is a set of programs. It is the interface between user and computer. It crates the user friendly environment. The operating system collets the various recourses ( printer, tape, disks etc.,)  and grant these resources to various process. For an example we want to copy a program in DOS operating system, just we type the command that will copy the program ( C: copy source destination).

Ex: we want to copy a program without operating system, then we have to write a program for copy command, then only we can copy the file. It is very difficult processing, so the main purpose of the operating system is to crate user friendly environment.

HISTORY OF OS OPERATING SYSTEM: 

In early 1980. When the IBM Computer Company was search of the Operating System. Which can take the full advantage of the system. It was released in 1981 on August 11^th  , The IBM was named the operating system as P.C.DOS. Then the 86 DOS was Changed into DOS for IBM Corporation by Tim Paterson.

Unix is also a multi user Operating System. It is developed in 1967 at  'C' Language is the middle Level Language developed for developing Unix laborating system at Berkeley Laboratory

Xenix is a modified from 'F' unix workable on all PC's. VAX Operating System is generally meanted for main for mainframe computers.

Z-80 is Zelog unix Operating System.

Types of Operating System: 

The Operating System mainly classified into following types.

1. Single user Operating System.

2. Multi user Operating System.

3. Time Sharing Operating System.

4. ON Line Operating System.

5. Multi Programming Operating System.

6. Multi Process of Operating System.

7. Virtual Operating System.

The Multi Processor and the time sharing Operating System are named by the Concept of instructions. Single User Operating System:

Example:         (a) PC. DOS 

                       (b) MS-DOS

Multi User Operating System:

Example:          Unix, Xenix, VAX

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