What is Computer Memory ? Describe of Memory classification?

Introduction:
One of the major advantages of computer is its storage capacity where huge amount of information can be stored,but how this information is represented and stored? In this chapter,we are going to learn about the various data storage devices and the units which are used to measure the stored data.

In the previous chapter,we studied the different types of input devices. But when the data and instructions are entered in the computer, Where they are stored.In fact, inside the computer, there are different storage areas where it keeps data or information permanently or temporarily while working. This storage area is known as the Memory of the computer.
A memory is just like a human brain. It is used to store data and instructions. Computer memory is the storage space in the computer,

The memory of the computer is divided into two categories:

1. Primary Memory

2. Secondary Memory

Primary Memory:-
This is the main memory of the computer. CPU can directly read or write on this memory. It is fixed on the motherboard of the computer.
Primary memory holds only those data and instructions on which the computer is currently working. It has a limited capacity. These memories are not as fast as registers. The data and instruction required to be processed resides in the main memory.
A computer cannot run without the primary memory.
Primary memory is further divided in two types:

A) RAM (Random Access Memory)

B) ROM (Read Only Memory)

A) RAM (Random Access Memory):- 

RAM is a temporary memory. The information stored in this memory is lost as the power supply to the computer is turned off. That's 

why it is also called Volatile Memory. It stores the data and instruction given by the user and also the results produced by the computer temporarily.

B) ROM (Read only Memory)
Information stored in ROM is permanent in nature,i.e., it holds the data even if the system is switched off. It holds the starting instructions for the computer. ROM cannot be overwritten by the computer. It is also called Non-Volatile Memory.

Secondary Memory:-
This memory is permanent in nature. It is used to store the different programs and the information permanently (which were temporarily stored in RAM). It holds the information till we erase it.

Different types of secondary storage devices are:

Hard Disc, Compact Disc, DVD, Pen Drive, Flash Drive, etc.
Harddisk:
This is the main storage device of the computer which is fixed inside the CPU box. Its storage capacity is very high that varies from 200 GB to 3 TB. As it is fixed inside the CPU box.

Compact Disk:
It is a thin plastic disc coated with metal. Computer can read and write data stored on it. This is an optical storage device with a storage capacity of up to 700 MB and it can store varieties of data like pictures,sounds,movies,texts,etc.

CD-ROM:
CD-ROM refers to Compact Disc-Read Only Memory. Data or information is recorded at the time of manufacturing and it can only be read. A CD-ROM cannot be used to record fresh data by the computer.

CD-R:
CD-R is the short form of Compact Disc-Recordable. Data can be written on it once and can be read whenever required. The data written once cannot be erased.

CD-RW:
CD-RW stands for Compact Disc Re-writable. CD-RW can be used to write information over and over again,i.e,previous information can be erased and new information can be written on it using a CD writer fixed inside the CPU box.

DVD:
DVD stands for Digital Versatile Disc. It is an optical storage device which reads data faster than a CD.A single layer,single sided DVD can store data up to 4.7 GB,i.e,around 6 times than that of CD and a double layer DVD can store data up to 17.08 GB,i.e.,around 25 times that of CD. Though DVDs look just like CDs,they can hold much more data,for example,a full length movie.

Flash Drive:
It is an electronic memory device popularly known as pen drive in which data can be stored permanently and erased when not needed. It is a portable storage device that can be easily connected and removed from the CPU to store data in it. It's capacity can vary form 2 GB to 256 GB.

Blue Ray:
This is a newly invented optical data storage device whose storage capacity can be form 25 GB up to 200 GB. It is mainly used to store high quality sound and movie data. They are the scratch resistant discs,that’s why,storing data on these is much safer than a CD OR DVD.

So,these are some the common devices we use to store information and data in the computer.

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What is Computer Hardware ? Explain Hardware device classification.

Computer hardware refers to the physical devices that make up a computer. Examples include the keyboard, monitor and disk drive.

Hardware devices can be classified into four distinct categories:

• Input devices: For raw data input.
• Processing devices: To process raw data instructions into information.
  
• Output devices: To disseminate data and information.
• Storage devices: For data and information retention.

1. Input Devices

Components which are used to input raw data are categorized under input devices. They aid in feeding data such as text, images, and audiovisual recordings. They even aid in file transfers between computers.

The keyboard is probably the most commonly used input device. Below are just some other types of input devices.

Input Type	Examples
Pointing Device	Mouse, touchpad, touchscreen, multi-touch screen, pen input, motion sensor, graphics tablet, interactive smartboard, and fingerprint scanner.
Game Controller	Joystick, gamepad, and steering wheel.
Audio Input Device	Microphone and midi keyboard.
Bluetooth Peripheral	Keyboard, mouse, headset, gamepad, printer.
Visual and Imaging Device	Webcam, digital camera, digital camcorder, TV capture card, biometric scanner, and barcode reader.
Network Device	Ethernet hardware and Bluetooth/wireless hardware.

2. Processing Devices

Processing is the core function of a computer. It is the stage where raw data is transformed into information. Once data has been processed, it can be used for useful 

The microprocessor is the major device in this category. It works closely with primary memory during its operations. Data is stored temporarily in processor cache and primary memory during the processing period.

The microprocessor is subdivided into three important units, which work together in order to accomplish its function. The units are:

• The control unit: It manages and supervises the operations of the processor and other components that are crucial in data manipulation.
• Arithmetic and logic unit: The ALU is responsible for all arithmetic and logic operations like addition, multiplication, subtraction, division, and comparison logic operations.
• Register and cache: These are storage locations inside the processor that respond to the instructions of the control unit by moving relevant data around during processin

3. Output Devices

Hardware components that disseminate and display both data and information are classified under the output category.

Output is the culmination of a cycle which starts with the input of raw data and processing.

These components are sub-categorized under softcopy and hardcopy output.

Softcopy output includes the intangible experience. The user derives visual satisfaction by reading a message through display components or listens to audio files through speakers.

On the other hand, hardcopy output devices are tangible, like printouts of paper and 3D model

Popular Softcopy Devices

Visual display devices include:

• Monitor

• Projection display

• smartboard

• Touchscreen

Sound devices include:

• Speakers
• Headphones and earphones

USB input/output includes:

• Flash drives

• External drives

• Optical drives

Popular Hardcopy Devices

Impact printers include:

• Dot matrix printer

• 3D printer

Non-impact printers include:

• Inkjet printer

• Laserjet printer

• Thermal printer

4. Memory/Storage Devices

Components that retain/store data are classified under memory/storage devices.

Storage is sub-divided under primary and secondary memory and is either volatile or nonvolatile.

Primary memory usually refers to random-access memory (RAM) but can also refer to all memory that works in tandem with the processor. RAM is volatile, meaning that it retains data only when the computer is powered up.

The central processing unit (CPU) or accelerated processing unit (APU) reads instructions stored in this memory and executes them as required.

Secondary memory is labeled as such because data stored within secondary storage media (usually disk drives) do not communicate directly with the microprocessor. Any data stored in such media is first transferred to a RAM device for processing to take place.

This type of memory is also non-volatile since it permits long time storage as opposed to volatile memory.

To give some examples of these devices, primary memory includes:

• DRAM
• SRAM
• ROM

Secondary memory is subdivided into two categories:

• Internal devices are designed to be placed inside the computer at all times. Examples include hard disk and solid state disk drives.

• External devices are plug and play media used to transfer files between computers. Examples include optical disks, flash disks, and external disk drive.

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Generation of Computer

Computer generations are based on when major technological changes in computers occurred:
Review each of the generations below for more information and examples of computers and technology that fall into each generation.

First generation (1940 - 1956):

The first generation of computers used Vacuum Tube as a major piece of technology. Vacuum tubes were widely used in computers from 1940 through 1956.

Vacuum tubes were larger components and resulted in first generation computers being quite large in size, taking up a lot of space in a room. Some of the first generation computers took up an entire room.

The ENIAC is a great example of a first generation computer. It consisted of nearly 20,000 vacuum tubes, as well as 10,000 capacitors and 70,000 resistors. It weighed over 30 tons and took up a lot of space, requiring a large room to house it. Other examples of first generation computers include the UNIVAC,IBM 701.

       The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

Second generation (1956 - 1963):

The second generation of computers saw the use of Transistor instead of vacuum tubes. Transistors were widely used in computers from 1956 to 1963.

Transistors were smaller than vacuum tubes and allowed computers to be smaller in size, faster in speed, and cheaper to build.

High level Programming Language were also being developed at this time, such as early versions of COBOL or FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

Third generation (1964 - 1971):

The third generation of computers introduced the use of IC(integrated circuits) in computers. Using IC's in computers helped reduce the size of computers even more compared to second-generation computers, as well as make them faster.

Fourth generation (1972 - Present):

The Microprocessor (VLSI - Very Large Scale of Integration) brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. 

What in the first generation filled an entire room could now fit in the palm of the hand. In 1981 IBM introduced its first computer for the home user.

Fifth Generation (Present and Beyond):
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Best example: ROBOT

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What is Computer? And Explain classification of Computer?

What is Computer? 

A computer is a programmable electronic device that accepts raw data as input and processes it with a set of instructions (a program) to produce the result as output.

The term "computer" is derived from the Latin word "computare" which means to compute or calculate. Abacus is the first calculating device which is invented in China and Egyptian people.

It is believed that the Analytical Engine was the first computer which was invented by Charles Babbage in 1837. It used punch cards as read-only memory. Charles Babbage is also known as the father of the computer.

Classification of Computer 

A) ACCORDING TO SIZE AND STORAGE CAPACITY

1. Micro Computer

2. Mini Computer

3. Mainframe Computer

4. Super Computer

1. Micro Computer

It is a single-user computer which has less speed and storage capacity than the other types. It uses a microprocessor as a CPU. The common examples of microcomputers include laptops, desktop computers, personal digital assistant (PDA), tablets, and smartphones. 

2. Mini Computer

Mini-computers are also known as "Midrange Computers." They are multi-user computers designed to support multiple users simultaneously. So, they are generally used by small businesses and firms. Individual departments of a company use these computers for specific purposes. 

3. Mainframe computer

It is also a multi-user computer capable of supporting thousands of users simultaneously. They are used by large firms and government organizations to run their business operations as they can store and process large amounts of data. For example, Banks, universities, and insurance companies use mainframe computers to store the data of their customers, students, and policyholders, respectively.

4. Super Computer

Super-computers are the fastest and most expensive computers among all types of computers. They have huge storage capacities and computing speeds and thus can perform millions of instructions per second. The super-computers are task-specific and thus used for specialized applications such as large-scale numerical problems in scientific and engineering disciplines including applications in electronics, petroleum engineering, weather forecasting, medicine, space research and more. For example, NASA uses supercomputers for launching space satellites and monitoring and controlling them for space exploration, it is also used Weather Forecasing purpose.

B) Accourding to the functionality:

1. Analog Computer 

 An analog computer (spelt analogue in British English) is a form of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved.

2. Digital Computer

 A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system (0,1).

3. Hybrid Computer (Analog + Digital)

 A combination of computers those are capable of inputting and outputting in both digital and analog.

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Extension Name or file format of MS Word

Microsoft Word Document File Format(DOCX/DOC)

The DOCX and DOC file extensions are used for Microsoft Word documents.

.DOCX

DOCX is part of Microsoft Office Open XML specification (also known as OOXML or OpenXML) and was introduced with Office 2007. DOCX is a zipped, XML-based file format. Microsoft Word 2007 and later use DOCX as the default file format when creating a new document. Support for loading and saving legacy DOC files is also included.

.DOC

DOC is the default format used with Office 97-2003. DOC is a Microsoft proprietary Binary Interchange File Format. Microsoft Word 97-2003 uses DOC as the default file format when creating a new document. Support for loading and saving DOCX files can be added using an add-in.



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What does the Microsoft Word editor look like?

Below is an overview of a Microsoft Word 2010 document.

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What is MS Word ?

MS Word is a widely used commercial word processor designed by Microsoft.
And a Word Processor is a device or computer program that provides for input, editing, formatting and output of text, often with some additional features.
It is also called Winword, MS Word or Word.

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MS Word Short Cut Key

Below is a listing of the more commonly used shortcut keys in Microsoft Word. See the computer shortcuts page if you are looking for a list of shortcut keys used in other programs. Please be aware that some of these shortcuts may not work in all versions of MS Word

Ctrl+D	Open the font preferences window.
Ctrl+E	Aligns the line or selected text to the center of the screen.
Ctrl+F	Open find box.
Ctrl+I	Italic highlighted selection.
Ctrl+J	Aligns the selected text or line to justify the screen.
Ctrl+K	Insert a hyperlink.
Ctrl+L	Aligns the line or selected text to the left of the screen.
Ctrl+M	Indent the paragraph.
Ctrl+N	Opens new, blank document window.
Ctrl+O	Opens the dialog box or page for selecting a file to open.
Ctrl+P	Open the print window.
Ctrl+R	Aligns the line or selected text to the right of the screen.
Ctrl+S	Save the open document. Like Shift+F12.
Alt+F, A	Save the document under a different file name.
Ctrl+A	Select all content of the page.
Ctrl+C	Copy selected text.
Ctrl+U	Underline the selected text.
Ctrl+V	Paste.
Ctrl+W	Close the currently open document.
Ctrl+X	Cut selected text.
Ctrl+Y	Redo the last action performed.
Ctrl+Z	Undo last action.
Ctrl+Shift+L	Quickly create a bullet point.
Ctrl+Shift+F	Change the font.
Ctrl+Shift+>	Increase selected font +1pts up to 12pt and then increase font +2pts.
Ctrl+]	Increase selected font +1pts.
Ctrl+Shift+<	Decrease selected font -1pts if 12pt or lower; if above 12, decreases font by +2pt.
Ctrl+[	Decrease selected font -1pts.
Ctrl+B	Bold highlighted selection.
Ctrl+Shift+*	View or hide non printing characters.
Ctrl+<left arrow>	Moves one word to the left.
Ctrl+<right arrow>	Moves one word to the right.
Ctrl+<up arrow>	Moves to the beginning of the line or paragraph.
Ctrl+<down arrow>	Moves to the end of the paragraph.
Ctrl+Del	Deletes word to right of cursor.
Ctrl+Backspace	Deletes word to left of cursor.
Ctrl+End	Moves the cursor to the end of the document.
Ctrl+Home	Moves the cursor to the beginning of the document.
Ctrl+Spacebar	Reset highlighted text to the default font.
Ctrl+1	Single-space lines.
Ctrl+2	Double-space lines.
Ctrl+5	1.5-line spacing.
Ctrl+Alt+1	Changes text to heading 1.
Ctrl+Alt+2	Changes text to heading 2.
Ctrl+Alt+3	Changes text to heading 3.
Alt+Ctrl+F2	Open new document.
Ctrl+F1	Open the Task Pane.
Ctrl+F2	Display the print preview.
Ctrl+Shift+>	Increases the selected text size by one font size.
Ctrl+Shift+<	Decreases the selected text size by one font size.
Ctrl+Shift+F6	Switches to another open Microsoft Word document.
Ctrl+P	Prints
F5	Open the Find, Replace, and Go To window in Microsoft Word.
F7	Spellcheck and grammar check selected text or document.
F12	Save As.
Shift+F3	Change the text in Microsoft Word from uppercase to lowercase or a capital letter at the beginning of every word.
Shift+F12	Save the open document. Like Ctrl+S.
Shift+Enter	Create a soft break instead of a new paragraph.
Shift+Insert	Paste.
Shift+Alt+D	Insert the current date.
Shift+Alt+T	Insert the current time.

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