Interesting Facts, Information And Updates About World

What is Assembler? A computer will not understand any program written in a language, other than its machine language.  The programs written in other languages must be translated into the machine language.  Such translation is performed with the help of software.  "A program which translates an assembly language program into a machine language program is called an assembler ."   If an assembler which runs on a computer and produces the machine codes for the same computer then it is called self-assembler or resident assembler . If an assembler that runs on a computer and produces the machine codes for other computer then it is called Cross Assembler Assemblers are further divided into two types: One Pass Assembler and Two Pass Assembler One pass assembler is the assembler which assigns the memory addresses to the variables and translates the source code into machine code in the first pass simultaneously. A Two Pass Assembler is the assembler which reads the source code twice. I

FILE SYSTEM A file is an object on a computer that stores data, information, settings, or commands that are used with a computer program.  All of the files in the UNIX file system are organized into a multi-leveled hierarchy called a directory tree. UNIX File System is organized in tree structure. File tree can be arbitrarily deep.   File name must not longer than 256 characters. Single path name must not longer than 1023 characters. ORDINARY OR REGULAR FILES A large majority of the files found on UNIX and Linux systems are ordinary files. Ordinary files contain ASCII (human-readable) text, executable program binaries, program data, and more. DIRECTORIES A directory is a binary file used to track and locate other files and directories. The binary format is used so that directories containing large numbers of filenames can be search quickly. DEVICE (SPECIAL) FILES Device or special files are used for device I/O on UNIX and Linux systems. They appear in a file system just like an ord

What is UNIX? UNIX is an operating system which was first developed in the 1960s. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops. UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren't covered by a graphical program, or for when there is no windows interface available. First version of UNIX developed at the University of California Berkeley. The UNIX Operating System The UNIX operating system is made up of three parts:  1. The kernel 2. The shell 3. Utilities  THE KERNEL • The kernel of UNIX is the hub of the operating system. • It allocates time and memory to programs and handles the filestore and communications in response to system calls.  THE SHELL Shell is the command line interpreter.  Shell is just another program  A program or command which i nteracts with the kernel and it may be any of: built-in sh