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What are the various Input Devices?-Short Note- ‘Personal Identification Number – PIN’?

 

 

What are the various Input Devices?

 

The input devices consist of one or more physical devices through which data or program can be read in to the computer. The term input is used to describe the process of capturing or collecting raw data, at the beginning of computer based information system, in to a form that is usable by the computer for processing. Some times the data is processed right away(online processing), some times hours or days later or even longer (batch processing), as a result the data is often stored in a computer usable form, where it can be quickly retrieved at the time of processing with little or no longer intervention. Different types of input devices normally found in the business environment can be categorized as shown:

 

Categories of input Hardware:

 

A. Keyboard 1. Terminals 2. Dedicated data entry system.

 

B. Direct entry

 

1. Optical scanning

2. Magnetic ink character recognition

3. Light pen

4. Digitizers

5. Touch Screens etc.

 

A. Keyboard:   A computer key board is a sophisticated electromechanical component designed to create specialized electronic codes when a key is pressed. The codes are transmitted along the cables that connect the key board to the computer system unit or terminal, where the incoming code is analyzed and converted in to the appropriate computer usable code. Key boards come in variety of sizes and shapes and have certain number of features in common:

 

1. Standard type writer keys.

2. Function keys.

3. Cursor movement keys.

4. Numeric keys.

5. Special purpose keys.

 

Type writer keys are used to type text and other data. Functional keys are also called as programmable keys and are used to issue commands. Function keys are specific to software and their use is mentioned in the manual that comes along with the software. Cursor movement keys are used to move the cursor on the screen. Special purpose keys include Ctrl (control), Del (delete), INS (insert) and Alt (Alternate). Numeric keys are used to enter numbers for mathematical manipulations.

 

I. Terminals:   The terminal typically consists of a visual display screen, a key board and a communication link to hook the terminal up with the main computer system and is used for inputting data to and retrieving data from a remotely located main system. The terminals are of three types:

 

1. The low cost dumb terminal: This is entirely dependent on main computer system to which is connected. It cannot do any processing of its own and is used only for data input (keyboard) and retrieval (data is displayed on the monitor). An airline reservation uses dumb terminal at a customer check in station to check flight information stored in the mainframe computer system.

 

2. A smart terminal: can input and retrieve data and also do some limited processing on its own such as editing and verifying data. A bank loan officer may use a smart terminal to input the data, do some calculations and retrieve the data before approving a loan.

 

3. An intelligent terminal: can input and receive data as well as do its own processing. In addition to the key board, monitor and communication link, an intelligent terminal also includes a processing unit, storage capabilities, and software. This type of terminal is actually a micro computer.

 

The popular types of computer terminals used to enter data are:

 

1. Point of sale terminal.

2. Financial transaction terminal.

3. Executive work stations.

4. Portable terminal.

 

II. Dedicated data entry system:   When an organization has high volume data input requirements, it often uses a secondary computer usually a minicomputer that stores previously keyed in data for later processing by mainframe computer. This processing usually takes place at night when the main computers time is not taken by user requests. The group of terminals connected to the minicomputers that handle data entry and storage are called a dedicated data entry system. They only input and store data using key to tape or key to disk input systems.

 

B. Direct Entry:   Some input systems use direct entry or non key entry. Non key board entry systems minimize amount of human activity required to get data in to a computer usable form. Some of the direct entry devices are:

 

1. Card readers: It is used to read the holes in punched cards and transfer the appropriate electrical signals as input to the computer. These devices are used mostly by the schools and small business, whose data input is very small.

 

2. Scanning devices: These are developed to read hard copy data from source documents in to computers usable form. These devices use light sensitive equipment to scan bar codes, optical marks, type written characters, hand written and magnetic ink.   Bar code readers: Bar codes are generally used on groceries, cosmetics, paper back novels and so on. Bar codes are recorded on the products by the manufacturer and use a coding scheme called Universal Product Code. Two types of bar code readers are used.

 

1. Hand held scanners – the clerk passes over the tag with bar code.

2. Counter top scanners – to scan the information on to the computer.

 

Bar code readers are used for two main purposes:

 

1. The prices and product inventory numbers do not need to be keyed in eliminating the potential for many keying errors.

2. Sales data and inventory status stored on file are kept on a current status.

 

3. Optical Mark Readers: The device has a high intensity light inside that is directed in the form of a beam at the sheets of papers being fed through it. The beam scans the marked forms and detectors the number and location of the pencil marks.   The data is then converted into electrical signals for the computer. The optical mark technology is used widely for scoring examinations and inputting raw data recorded on questionnaires.

 

4. Type written and type set character scanner: Certain manufacturers have developed special type of fonts, to be read by a scanning device. ASCII has developed a standard font for use with special optical character reading devices. The popular fax machine is a type of scanner that reads text and graphics and transmits them over telephonic lines to a computer with a fax board or another fax machine.The technology has avoided the duplication of work, increased speed and reduced the cost of converting type written data to computers usable form.

 

5. Hand written character readers: These devices convert the hand written data to computer usable form.

 

6. Magnetic Ink Character Recognition (MICR): It is primarily used for processing cheques. This technology involves reading numeric character and few special symbols printed on cheque with magnetic ink. The figure shows MICR encoding on a personal cheque. Personal cheques are encoded with magnetic ink and it is read by MICR equipment. The data is then stored for processing.   The advantages of MICR system are :   Human involvement is minimal, thus the potential for errors is less. It is fast, automatic and reliable.

 

7. Smart Cards: It is used like a credit card. The card holder inserts the card in to a special card reading point of the sale terminal and then enters a password on the key board. The cards have microchips that can keep permanent records, which are updated each time the card is used. The transaction data stored on the card is later used via ATM to update the user’s bank records. In certain countries smart cards are used to buy merchandise, make phone calls, get exam results from the university etc.,

 

III. Voice input devices:   These devices convert the spoken words in to electrical signals and compare the electrical patterns produced by the speakers voice with a set of pre recorded patterns. If a matching pattern is found, the computer accepts this pattern as a part of its standard “vocabulary”.

 

IV. Pointing Devices: Data input also involves entering commands and selecting options. Certain devices allow the user to identify and select the necessary command or option by moving the cursor to a certain location on the screen and sending a signal to the computer.

 

Some of the pointing devices are:

 

1. Light pen: Uses a light sensitive photo electric cell to signal screen position to the computer. When a light pen is moved on the screen, it indicates x, y coordinates to the computer. It is used by graphic designer, drafting engineers etc.

 

2. Mouse: The mouse is a hand held device connected to the computer by a small cable. As the mouse is rolled across the desktop, the cursor moves across the screen, when the cursor reaches the desired location the user usually pushes a button on the mouse once or twice to signal a menu selection or a command to the computer. The keyboard must be still used to type in characters and issue some commands, depending on the software.

 

3. Touch screen: Limited amount of data can be entered via a terminal using touch screen. The user simply touches the screen at the desired locations, marked by labeled boxes to point out choices to the computer. The software determines the kind of choices the user has.

 

4. Digitizer: This tablet/device comes in different sizes, has the working surface. Each is converted by a grid of many tiny wires that is connected to the computer. Drawings placed over this grid can be traced and entered in to the computer by the use of special pen or mouse like device with cross hairs that opens and closes electrical circuits in the grid and thus identifies x-y coordinates. Original drawing may also be entered. As it progresses, the drawings are displayed on the screen. It can later be stored or printed out. Digitizers are used in design and engineering businesses such as those that develop aircraft or computer chips.

 

5. Touch tone devices: Used to send data to a computer. A computerized, voice requests check data against its files and reports back on the screen.

 

Memory Size: All digital computers use the binary system, i.e. 0’s and 1’s. Each character or a number is represented by an 8 bit code.

 

 The set of 8 bits is called a byte.

 A character occupies 1 byte space.

 A numeric occupies 2 byte space.

 Byte is the space occupied in the memory.

 

The size of the primary storage is specified in KB (Kilobytes) or MB (Megabyte). One KB is equal to 1024 bytes and one MB is equal to 1000KB. The size of the primary storage in a typical PC usually starts at 16MB. PCs having 32 MB, 48MB, 128 MB, 256MB memory are quite common.

 

 

Short Notes

 

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme originally based on the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text. Most modern character-encoding schemes are based on ASCII, though they support many additional characters. It was only developed for communication and first adopted in 1963. ASCII has been very popular in the computer world. It contains seven bits to define each letter or character excluding eighth bit for error-checking function. There are 128 specific characters including capital letters, small letters, 0 to 9 digit, special symbols and some specific character having specific different functions. Thirty-three codes are used to represent things other than specific characters. The first 32 (0-31) codes represent a chime sound, used to feed line as well as to start of a header. The final code, 127 represents a backspace while the first 31 bits are the printable characters. Bits ranging from 48 to 57 represent the numeric digits and 65 to 90 represents the capital letters, while bits 97 to 122 are the lower-case letters. The rest bits represent symbols of punctuation, mathematical symbols, and other symbols such as the pipe and tilde. Earlier ASCII was developed only in six bits for a simpler character set. But finally it has been reconstructed using seven bits for assimilating lower-case letters, punctuation, and control character sets to enhance its utility. No other than English characters has been used in ASCII. ASCII is not used in IBM computers. IBM has its own built-in-code called EBCDIC code containing 256 character sets. Nowadays Unicode character set is replacing ASCII code very rapidly. ASCII is being famous in ASCII art phase that describes the use of the basic character set to create visual approximations of images.

 

‘Personal Identification Number – PIN’

 

A personal identification number is a secret numeric password shared between a user and a system that can be used to authenticate the user to the system. Typically, the user is required to provide a non-confidential user identifier or token (the user ID) and a confidential PIN to gain access to the system. Upon receiving the user ID and PIN, the system looks up the PIN based upon the user ID and compares the looked-up PIN with the received PIN. The user is granted access only when the number entered matches with the number stored in the system. Hence, despite the name, a PIN does not personally identify the user.   PINs are most often used for automated teller machines (ATMs) but are increasingly used at the point of sale, for debit cards and credit cards.

 

For example, when you take money out of an ATM, you enter your PIN number to prove that you’re authorized to make the withdrawal. You might also enter a PIN number if you use your debit card at a retailer (only for POS transactions, not signature transactions). UPS Short for uninterruptible power supply, a power supply that includes a battery to maintain power in the event of a power outage. Typically, a UPS keeps a computer running for several minutes after a power outage, enabling you to save data that is in RAM and shut down the computer gracefully. Many UPSs now offer a software component that enables you to automate backup and shut down procedures in case there’s a power failure while you’re away from the computer.   There are two basic types of UPS systems: standby power systems (SPSs) and on-line UPS systems. An SPS monitors the power line and switches to battery power as soon as it detects a problem. The switch to battery, however, can require several milliseconds, during which time the computer is not receiving any power. Standby Power Systems are sometimes called Line-interactive UPSes.

 

An on-line UPS avoids these momentary power lapses by constantly providing power from its own inverter, even when the power line is functioning properly. In general, on-line UPSs are much more expensive than SPSs. A UPS is typically used to protect computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units range in size from units designed to protect a single computer without a video monitor (around 200 VA rating) to large units powering entire data centers or buildings RDBMS.   RDBMS stands for Relational Database Management System. RDBMS data is structured in database tables, fields and records.

 

Each RDBMS table consists of database table rows. Each database table row consists of one or more database table fields. An important feature of relational systems is that a single database can be spread across several tables. This differs from flat-file databases, in which each database is self-contained in a single table.   RDBMS store the data into collection of tables, which might be related by common fields (database table columns). RDBMS also provide relational operators to manipulate the data stored into the database tables. Most RDBMS use SQL as database query language.   Relational database management system (DBMS) stores data in the form of related tables. Relational databases are powerful because they require few assumptions about how data is related or how it will be extracted from the database. As a result, the same database can be viewed in many different ways. RAM.   RAM is an acronym for random access memory, a type of computer memory that can be accessed randomly; any byte of memory can be accessed without touching the preceding bytes. RAM is the most common type of memory found in computers and other devices, such as printers. RAM is a temporary storage for data. For instance, when you open Microsoft Word (or any program), it goes into RAM because your CPU can get it a lot faster from RAM, than if it tried to get it off of your hard drive.

 

However, RAM is dynamic which means if the power is cut off then any data that is in RAM is lost. Let’s say you are typing a letter, each time you hit the keyboard that data is put into RAM until it can be transferred to your hard drive. If the power goes off then whatever is in RAM while you were typing will be lost. In common usage, the term RAM is synonymous with main memory, the memory available to programs. For example, a computer with 8MB RAM has approximately 8 million bytes of memory that programs can use. In contrast, ROM (read-only memory) refers to special memory used to store programs that boot the computer and perform diagnostics. Most personal computers have a small amount of ROM (a few thousand bytes). In fact, both types of memory (ROM and RAM) allow random access. To be precise, therefore, RAM should be referred to as read/write RAM and ROM as read-only RAM.

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