Lec 5 input unit

WELCOME

MIS – 104:

Computing Fundamentals

BBA Department of MISUniversity of Dhaka

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Books

1. Introduction to Computer Peter Norton

2. Computer Fundamentals Dr. M Lutfar Rahman

3. Computer Fundamentals Pradeep K. Sinha

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Last Class1. Computer:

Introduction Characteristics

Use (Specially in Business)HistoryGeneration

2. Classification of Computer: • Size & volume of data processing

– Micro, mini, mainframe, super• Working principle

– Analog, digital, hybrid• Purpose of use

– Special purpose, general purpose

Today’s Class

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Outline

3. Basic Organization of Computer: Input Unit Output Unit Memory Unit Control Unit Arithmetic & Logic Unit (ALU)

CPU = ALU + CU

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Organization

CPUInput Unit Output UnitALU

Control Unit

Memory Unit

Today’s Class

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Course Outline

4. Input UnitKeyboard, Mouse, Scanner, OMR, OCR, MICRBarcode readerMicrophoneJoystickDigital CameraLight PenTrack Ball

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Input unit: Keyboard

• One of the most common input device• Types: There are two types of keyboard- QWERTY • Number of keys: From 102 to 108/110• Function: Primary device for entering text and

numbering

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• Description: `QWERTY` keyboard

• The name of this keyboard comes from the first 06 alphabets placed at the top

• Keyboard adapter contains `8-bit ASCII code`

• micro- processor sends keystroke through BUS.

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Keyboard

• There are 06 types of keys:

1. Alphanumeric key2. Modifier key3. Function Key4. Numeric Keypad5. Cursor Movement Key6. Special Purpose Key

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• Description: Alphanumeric keys

• It includes over 50 keys consumes most of the area of keyboard

• Ex-A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z, -,=,+,<,>,$,{,[,},@,$,%,^,& etc

• Besides there are 04 keys whose have special purpose like `TAB,ENTER,CAPSLOCK,BACKSPACE`

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• Description: Modifier keys

• Some keys modifies the input of other keys

• Example: – Shift, – Alt, – Ctrl

• Application: In MS Word if you press (Ctrl and A) immediately then all the written text will be selected. Here alphabet `A` will be modified due to “Ctrl” key.

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• Description: Numeric keypad

• Usually located at the right side of the keyboard like calculator keys

• There is a key called `Num Lock`. When it is off keypad performs as cursor movement

• Example: 1,2,3,4,5,6,7,8,9,0,/,*,.,-,+ etc

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• Description: Function keys

• Located at the top row of the keyboard

• Usually with this we can input command without typing long strings

• Their function varies with the variation of running program

• There are 12 function keys like F1, F2, F3,……..F12

• For almost all programs, F1 = Help

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• Description: Cursor-movement keys

• With the help of these keys we can move the cursor or Insertion point according to our desire

• Example: keys marked with arrows

• Others are: – Page up, Page down, Home,

End

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• Description: Special purpose key

• They are desired to work with `Operating system`

• Example: “Windows logo key” usually used to start windows operating system

• Besides there is another key whose work is as like as ` Right button` of mouse

• Rests are: ESCAPE, INSERT, DELETE, PRINT SCREEN, SCROLL LOCK, PAUSE

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How keyboard works?

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How keyboard works?

• It's a complex function, described below-1. Suppose, a key is pressed on keyboard2. The` keyboard controller` sends the scan

code for that key to the `keyboard buffer`3. The keyboard controller sends an

`interrupt` request to the system software4. The `system software` responds to the

interruption.

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How keyboard works?

5. The system software can read the scan code from keyboard buffer that’s why it can respond.

6. The system software passes the scan code to CPU

7. Then for an input key we can see the output result

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Continuous pressing of key………..

• There is a standard & specific time to show output for a key ,

• when a key is pressed for more than that time, after a definite time it thinks that the key has pressed again.

• The same steps what it followed starts to follow again. Thus we see the same output consecutively.

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Input device: Mouse

• A mouse is a `pointing device`

• Used to control the position of the cursor

• There are 02 types of mouse-– Mechanical– Optical

• A standard mouse has 02 buttons and a scroll Mechanical mouse has a ball (also call `ball mouse`) and Optical mouse has 02 light sources

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Input device: Mouse

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Input device: Mouse

• Function: – A mechanical mouse has some sensors inside it,

with the help of ball they are touched and moved to change the position of the cursor

– An optical mouse has 2 sensory light sources, the amount of `light reflected` from surface determine the position of X-Y axis in the monitor

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Other functions of mouse

• Single click: – to select any file or folder

• Double click: – to open an icon/file/folder

• Dragging: (also called Drag-&-drop-editing) – To drag an item and place It in a new position for further

operation• Right click:

– Usually opens a shortcut menu which contains commands and options.

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Advantages of mouse

1. To select or open any file or folder without using cursor movement key

2. Sometimes to input command without using keyboard

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Input device: Scanner

• They are mostly used to input printers, photography etc directly inside the computer

• There are three types of scanner-1. Flatbed:

– Large, can't be carried but a large size image can be scanned2. Hand hold:

– Small, can be carried but a large size image can not be scanned3. Sheet fed:

– Used to scan single, ordinary size sheets

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Input device: Scanner (How it works?)

1. A light source is moved across the page2. The light bounces of the page & is passed through

a lens..3. Light sensitive Diodes convert reflected light into

electric signal.4. Circuit board converts the electric signals into

digital numbers & sends the information to the computers

5. Overall, sensing the intensity of light reflection is important here

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Colour Scanner

• The colour scanners use filters to separate the components into `Primary additive colours`( RGB- means Red, Green, Blue).

• RGB can be combined to produce any type of other colours.

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Input device: OCR

• Means `Optical Character Reader`

• Generally it is used in the banks, with the help of OCR the complex process of deposit & withdraw of money can be done easily & quickly

• OCR requires- 01. Specified symbol 02. Specified ink 03. Specified paper

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Input device: OCR (How it works?)

1. Light ray scan the paper and the light is reflected back

2. Reflected ray is converted into electric signal by light sensitive diodes

3. A circuit board converts the electric signal into digital numbers and send it to CPU

4. CPU taking data calculate it i.e. addition or deduction of numbers and show output

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Input device: OMR

• Means- `Optical Mark Reader`

• Generally used to examine the objective type questions, also do other functions

• Requires:– Specified paper– Specified ink

• Working procedure is as like as OCR

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Input device: MICR

• Means- `Magnetic Ink Character Reader`

• This system can read data pre-recorded on checks & deposit slips with a special ferrite-impregnated ink.

• The magnetized character can be read & interpreted by MICR equipment

• Primary means of processing checks

• Can read numeric characters and special symbols printed with magnetic ink

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Input device: MICR

Requirements:– Cheque routine symbol– Bankers transit number – Customer account number – Cheque number – Cheque account

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MICR: Advantages

• Human involvement is minimal• Error chance is less• It is fast, automatic and reliable• If there is any mistake, then automatic

detection of error

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Input device: Barcode reader

• A device for reading barcodes of different width and spacing with same length

• Generally used in the departmental stores & industries to identify goods

• Barcode reader has organized primarily with a light source & a light sensor which connected with the CPU through cable

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Barcode reader: (How it works?)

• When this machine is on then the ray falls on the printed bar & this light ray is reflected

• This ray is converted into the signals which is understable by the CPU

• Then database examine the incoming data & identify the products

• At last CPU shows result on monitor or print through special printer called `POS printer`

Question...???

Next Class

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Course Outline

5. Output UnitPrinterMonitorplotterSpeaker

Touch Screen

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Course Outline

6. Memory UnitDefinitions: Classification

Processor: RegistersPrimary: RAM, ROMSecondary: FDD, HDD, Tape

FDDHDDCDROMDVD ROMChache MemoryVirtual memory

Thank You

Lec 5 input unit

Education

Transcript of Lec 5 input unit