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Basic Definition of Software:-                                                  Software refer to the programs that instruct the computer what to do.Software makes the computer useful.Software is the general name given to all the programs (instruction) and data necessary to make the computer usable.The term software refer to the non-physical elements of a computer system. Windows, Visual Basic, Avast Antivirus, Microsoft Word, Microsoft Excel are the examples of Software.

Basic Definition Of Hardware :-                                                                 The physical or tangible components forming a computer are called Hardware.When people talk about a computer,they usually mean the hardware.Hardware is a collective term.It includes not only the computer but also the cable,connecters,power supply units and peripheral devices such as the keyboard,mouse,audit speaker,printer,etc. The term is used to distinguish these fixed parts of a system form the changeable software or data components,which it executes,stores,or carries.

A CD-ROM / ˌ s iː ˌ d iː ˈ r ɒ m / is a pre-pressed optical compact disc which contains data. The name is an acronym which stands for " Compact Disc Read-Only Memory ". Computers can read CD-ROMs, but cannot write on the CD-ROM's which are not writable or erasable. Until the mid-2000s, CD-ROMs were popularly used to distribute software for computers and video game consoles. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). The Yellow Book is the technical standard that defines the format of CD-ROMs. One of a set of color-bound books that contain the technical specifications for all CD formats, the Yellow Book , created by Sony and Philips in 1988, was the first extension of Compact Disc Digital Audio. It adapted the format to hold any form of data.

An EPROM (rarely EROM), or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits. Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light source (such as from a mercury-vapor light). EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip is visible, and which permits exposure to UV light during erasing. Operation

EEPROM also written E 2 PROM and pronounced "e-e-prom", "double-e prom", "e-squared", or simply "e-prom") stands for E lectrically E rasable P rogrammable R ead- O nly M emory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration tables or device configuration. Unlike bytes in most other kinds of non-volatile memory, individual bytes in a traditional EEPROM can be independently read, erased, and re-written. When larger amounts of static data are to be stored (such as in USB flash drives) a specific type of EEPROM such as flash memory is more economical than traditional EEPROM devices. EEPROMs are organized as arrays of floating-gate transistors. An EPROM usually must be removed from the device for erasing and programming, whereas EEPROMs can be programmed and erased in-circuit, by applying special programming sign

In information technology, a write-only memory ( WOM ) is a memory location or register that can be written to but not read. In addition to its literal meaning, the term may be applied to a situation when the data written by one circuit can be read only by other circuitry. The most common occurrence of the latter situation is when a processor writes data to a write-only register of hardware the processor is controlling. The hardware can read the instruction but the processor cannot. This can lead to problems in producing device drivers for the hardware. Write-only memories also find applications in security and cryptography as a means of preventing data being intercepted as it is being decrypted. Hardware uses In 1972, WOM, an antithesis of read-only memory (ROM), was introduced as an inside practical joke perpetrated by Signetics. [ 1 ] However it was soon recognized that this concept actually describes certain functionalities in microprocessor systems. [ 2 ] The

  Read-only memory ( ROM ) is a class of storage medium used in computers and other electronic devices. Data stored in ROM can only be modified slowly or with difficulty, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to need frequent updates). Strictly, read-only memory refers to memory that is hard-wired, such as diode matrix and the later mask ROM . Although discrete circuits can be altered in principle, ICs cannot and are useless if the data are bad. Despite the simplicity, speed and economies of scale of mask ROM, field-programmability often make reprogrammable memories more flexible and inexpensive. As of 2007, actual ROM circuitry is therefore mainly used for applications such as microcode, and similar structures, on various kinds of processors. Other types of non-volatile memory such as erasable programmable read only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM or

Random-access memory ( RAM / r æ m / ) is a form of computer data storage. A random-access memory device allows data items to be read and written in roughly the same amount of time regardless of the order in which data items are accessed. [1] In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement delays. Today, random-access memory takes the form of integrated circuits. Strictly speaking, modern types of DRAM are not random access, as data is read in bursts, although the name DRAM / RAM has stuck. However, many types of SRAM are still random access even in a strict sense. RAM is normally associated with volatile types of memory (such as DRAM memory modules), where stored information is lost if the power is