Machine Language
Machine language is the only language that a compute understands
directly without any translation, it is the binary language. It is the
language of 0′s and 1′s . It consists of strings of binary numbers.
The binary codes are very difficult to memorize for human beings that is why a machine language is cumbersome for a user.
The binary codes are very difficult to memorize for human beings that is why a machine language is cumbersome for a user.
Difference Between a High-Level Language and Low-Level Language
High-Level Languages
High-Level language are more suitable for human use than machine
languages and enable the programmer to write instructions easily using
English words and familiar mathematical symbols. These symbolic
languages are called High-Level languages. These high-level languages
consist of simple English sentences, which are very easy to understand
and memorize for human being.
Low-Level Languages
Both the machine and assembly languages are called Low-Level
Languages. An assembly language is one step higher than the machine
language in human readability. A machine language consists of totally of
numbers and is almost impossible for humans to read. In an assembly
language, some of these numbers are replaced by human readable symbols
called language for humans and almost of the same efficiency as machine
language for computer operations. An assembly language is a combination
of mnemonic operation codes and symbolic codes for address.
Assembly language is very difficult but it requires good skills for programming. A program written in an assembly language is translated into a machine language before computer can understand and execute it. A computer program, which translates an assembly language program into its equivalent machine language, is called assembler.
A program can be written in much shorter time and much precisely when a high level language is used. A program written in a high level language can be executed in any computer system, which has a compiler for that programming language.
Assembly language is very difficult but it requires good skills for programming. A program written in an assembly language is translated into a machine language before computer can understand and execute it. A computer program, which translates an assembly language program into its equivalent machine language, is called assembler.
A program can be written in much shorter time and much precisely when a high level language is used. A program written in a high level language can be executed in any computer system, which has a compiler for that programming language.
Operating System
Operating system provides link between the user and the computer. It
enables the user to have complete control over the computer system by
commands through the keyboard or any other input device. The supervisor
part of an operating system resides all the times in the memory (RAM) of
the computer after the computer is turned on. An operating system
performs the following tasks:
1. Controls basic Input and Output devices.
2. Allocates system resources.
3. Manages storage space
4. Supports application software
5. Maintains security
6. Detects equipment failure
This enables the user to achieve high efficiencies of which the processing systems are capable. Operating systems can be classified as:
1. Single User Operating System
2. Multi-User Operating System
1. Controls basic Input and Output devices.
2. Allocates system resources.
3. Manages storage space
4. Supports application software
5. Maintains security
6. Detects equipment failure
This enables the user to achieve high efficiencies of which the processing systems are capable. Operating systems can be classified as:
1. Single User Operating System
2. Multi-User Operating System
1. Single User Operating System
Single user operating systems are used on individual systems or
Personal Computers. These operating systems reside on disks and re
called Disk Operating Systems (DOS). Some of the most widely used single
user operating systems are :
1. MS-DOS
2. PCDOS
3. OS/2
4. Windows 95
1. MS-DOS
2. PCDOS
3. OS/2
4. Windows 95
2. Multi-User Operating System
Multi-User Operating Systems are used for data processing on lrge
computer systems. They enhance the potential of computer systems with
multiprogramming, multiprocessing and timesharing facilities making them
suitable for large organizations. Some of the multi-user operating
systems are:
1. UNIX / XENIX
2. MACOSX
3. Windows NT
4. Windows 2000 Server
1. UNIX / XENIX
2. MACOSX
3. Windows NT
4. Windows 2000 Server
DOS
DOS stands for “Disk Operating System”. It is a program, which acts
as an interface between the user and the computer hardware. DOS allows
manipulation of files and programs by interpreting and processing the
commands typed by the user.
The DOS software is automatically copied from a floppy disk or the hard drive into the computer’s memory whenever the computer is turned on or booted(made a computer ready to be used by putting in its instructions). DOS is not an application package that you start and then exit when done. This is an operating system runs from the moment you turn the computer on until you turn the machine off. The major tasks the DOS must carry out are:
1. To control input and output devices.
2. To enable user to load and execute program.
3. To maintain an orderly system of data in the disk.
The DOS software is automatically copied from a floppy disk or the hard drive into the computer’s memory whenever the computer is turned on or booted(made a computer ready to be used by putting in its instructions). DOS is not an application package that you start and then exit when done. This is an operating system runs from the moment you turn the computer on until you turn the machine off. The major tasks the DOS must carry out are:
1. To control input and output devices.
2. To enable user to load and execute program.
3. To maintain an orderly system of data in the disk.
Types of DOS Commands
There are two types of DOS Commands:
1. Internal Commands
2. External Commands
1. Internal Commands
2. External Commands
1. Internal Commands
Internal commands are a part of the DOS program COMMAND.COM and are
loaded into memory when you boot your computer. These commands are
needed to be used most often, although they are not seen when we display
the disk directory of filenames on our screen. Some internal DOS
commands are:
CLS
This command is used to clear the screen of a monitor.
Syntax: CLS
Syntax: CLS
DIR
This command is used to display a list of current directly files and subdirectories.
Syntax: DIR[drive:][path][filename][/p][1w]
Syntax: DIR[drive:][path][filename][/p][1w]
CHDIR (CD)
This command is used to display the current directory or changes in the current (default) directory.
Syntax: CD[drive:][path]
Syntax: CD[drive:][path]
DEL
This command is used to deletes one or more specified files from the disk.
Syntax: DEL[drive][path]file name[/p]
e.g. DEL Aslam.Doc
Syntax: DEL[drive][path]file name[/p]
e.g. DEL Aslam.Doc
External Commands
External Commands are programs, which exist on the DOS disk or the
hard disk. They are run when you type their name on the command line.
For example, typing FORMAT at the DOS prompt results in a program called
FORMAT.COM being executed.
External Commands are not frequently used and DOS saves valuable memory space by loading them only when required. Some the external commands are:
External Commands are not frequently used and DOS saves valuable memory space by loading them only when required. Some the external commands are:
CHKDSK
This command is used to checks the validity of a disk and reports the total space, used and free space on the selected disk.
Syntax: CHKDSK [drive][path][/f][/v]
Syntax: CHKDSK [drive][path][/f][/v]
SYS
This command is used to create a bootable drive and installs the main DOS files.
Syntax: SYS[drive:][path]drive2:
e.g. SYS A:
Syntax: SYS[drive:][path]drive2:
e.g. SYS A:
TREE
This command is used to display directory structure.
Syntax: TREE[drive:][path][/f][/a]
Syntax: TREE[drive:][path][/f][/a]
XCOPY
This commands is used to copy files (except hidden and system files) and directories, including sub directories.
Syntax: XCOPY source [destination][/a|/m][/d:date][/p][/s][/e][/v][/w]
e.g. XCOPY *.*A:
Syntax: XCOPY source [destination][/a|/m][/d:date][/p][/s][/e][/v][/w]
e.g. XCOPY *.*A:
DELTREE
This command is used to delete all files and sub directories in a directory.
Syntax: DELTREE[/Y][pathname]
Syntax: DELTREE[/Y][pathname]
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