CBSE (UGC) NET Paper 1 Communication and Technology: Overview Of Computers
Overview Of Computers
Basically, Computers were invented to perform the numerical calculations in the the year 19308 − 408. But very soon they were developed to process all kinds of data such as numbers, texts, and other kinds of media. A computer system consists of two kinds of components: Hardware and software. Hardware is the equipment used to perform the essential computations and consists the central processing unit (CPU), monitor, keyboard, mouse, printer, and 80 on. Software consists of programs written in programming languages that takes care of the hardware to carry out different tasks. Whatever a computer needs to process are eventually translated into binary numbers, consisting of Os and le. The programs are translated into lists of instructions based on the binary numbers.
Major hardware components of a computer consist memory, processing unit, and input! output devices. Memory is the place w here the programs and data are stored. It can be imagined as an ordered sequence of storage locations called memory cells. Each cell has a unique address, which is like a serial number of the cell in the memory. The data stored in a memory cell are called the contents of the cell. Program treated as a special type of data. The concept of “stored program” let a program be stored in the memory before they can be done. A memory cell contains a sequence of binary digits, or bits. Each bit is either a 0 or a 1. A sequence of eight bits is generally called a byte, which represent a character, such the ones on a keyboard. To store a value into a certain address means to give it new contents (so the earlier one is gone). To retrieve a value from a memory cell means to copy the contents to another place without destroying it. In a computer, there are several kinds of memory. There is the distinction between main memory and secondary memory-the former is faster and smaller, but the latter is cheaper, and often removable. Recently, the former is generally in silicon chips, while the latter in hard disks, floppy disks, CDs and 80 on. There are two kinds of main memory:
RAM (random access memory) and ROM (read-only memory). Their differences are that the contents of RAM can be modified, and are generally volatile i.e.. will be lost when the computer is switched off. On the otber band, secondary memory is not volatile. In the following, ~main memory “means RAM. The terms used to quantify storage capacities: 1 byte (B) = 8 bite. 1 kilobyte (KB) = 1024 bytes, i.e.. 2 10 bytes 1 megabyte (MB) = 1024 kilobytes, i.e.. 220 bytes 1 gigabyte (GB) = 1024 megabytes. i.e.. 230 bytes 1 terabyte (fB) = 1024 gigabytes, i.e.. 2” 0 bytes In a computer, most. Of the operations are performed by a CPU (central processing unit.), though there are computers with multiple CPUs.
A CPU has two tasks: Coordination of all computer operations and performing arithmetic and logical operations on data. The CPU follows the instructions contained in a program (written in a computer-understandable language). In each step. The CPU fetches (i.e.. retrieves) an instruction, interprets its content to decide what to do, and then do it, which may mean to move data from one place to another, or change data in a certain way. Other common operations consist addition, subtraction, multiplication, division, comparison, and so on. CPU generally executes instructions one after another, but can also jump to another memory cell according to an instruction. At the current time. a CPU is in a single integrated circuit (IC), or call it a chip. A computer uscs its inputJoutput (I/O) devices to communicate with human uscs and other computers. For a human user, the usual input device is a keyboard and a mouse, and the usual output device is a monitor (display screen), and a printer. The human-computer interaction (Hef) can either happen in a command-line user interface. Or a graphical user interface (GUI). A computer network carries out communications among computer systems. There are different kinds of networks: Localarea network (LAN) and wide area network (WAN). The Internet connects computers allover the world. Which supports the World Wide Web WWW, among many of its usages. To connect to another computer, a computer needs a modem (modulator or demodulator), or some other network device, to translate between its internal language and the language used in the network communication. The communications depend on various kinds of cables or wireless.
In a computer, there is a software that occupies a special position: The operating system (OS). With respect to it, all other softwares are application softwares which are managed and supported by the OS. When a computer is turned on, it starts by executing part of the OS that is stored in a ROM, which then loads the rest of the OS from hard disk and starts it. This process is called “booting” When running, an OS has the following main responsibilities:
Another type of language are more human oriented, called “higher-level languages” which are closer to mathematical languages and natural languages (such as English), as well machine-independent. Typical examples of high-level language consist FORTRAN, ALGOL, COBOL, BASIC, Pascal, LISP, Prolog, Perl, C, C + +, and Java. Special programs accomplish the translation from high-level languages and assembly languages into machine languages: Compilers, interpreters, and assemblers. A compiler translates a source program in a high level language into an object-program in the machine language. An interpreter interprets and executes a program in a high-level language line by tine. An assembler translate8 a source program in an assembly language inti! an object program in the machine language. A high-level language generally comes with many readymade common programs, so the user can consist them in programs, neither than rewrite them. The program accountable for this is called a “linker” It links user object programs and related “library programs” and produces executable programs. There are software packages ca lled “integrated development environment” (IDE) which organize all the related software (e. g. editor, compiler, linker, loader, debugger) together to support the development of a software. During the execution of a program in machine language, it typically get some input data from the memory, process them according the predetermined procedure, then store some output data into the memory, and display some information to the user.
communicating with the user
allocating resources (CPU time, memory space, printer usage).
connection 1/0 devices With running programs.
transferring data between main and secondary memory. In summary. We often say t. Hat the OS manage processes and resources. At the current time, the most often used OS consist UnixlLinux, Microsoft Windows. And Macintosh OS. It is possible for a Computer to have more than one as stored in its memory. But generally only one can be used at a time. An application software uses the computer to accomplish a specific task. They are generally purchased on CD. And installed into the computer (so itia stored in memory and known to the OS), before they can be used in the computer. The CPU, in a machine language, in which a program is in binary code. Eventually executea every software. Since programs in this language are not easily understandable by a human user, the same program is generally also described in other, more human-readable languages. One type of them is a88Cmbly language. In which the instructions are represented by symbols and numbers.