2. 2.1 INPUT DEVICES
Input = Feed
Device = Electronic equipment)
Input Device – Device used to accept Data and Instructions from user
•Used to feed data and instructions into computer
•Converts Data – Recognised by computer (0 &1)
Examples :
Keyboard, Mouse, Trackball, Joystick, Scanner,
Light pen, Barcode Reader, OCR,OMR, MICR etc.
3. Trackball – Ball used in mouse for pointing
Light Pen – Used in light sensitive Devices to select, draw and
interact
OCR - Optical Character Recognition – Recognise the Character
OMR – Optical Mark Recognition
MICR – Magnetic Inc Character Recognition – To Scan Digital
Printed code on cheque (Bottom)
4. 2.1.1 Keyboard :
•Most Common Device
•Numbers (0.9), Characters (a-z, A-Z), Alpha Numeric (Number and
Charecter), Special Keys (Up,Down,Shift,Ctr ), Punctuation Keys (, . > < ? @ ! $
& ^ ( ) [] {}), Functional keys (F1 – F12)
•101 Keys / 104 Keys
• Converts the ASCII CODE for each Keys
•ASCII CODE American Standard Code of Information Interchange
6. Types of Keyboard
1.Standard Keyboard
•Basic Layout
•105/108 keys
•QWERTY in First row
2.Ergonomics
•Method to reduce stress on mussels on repetitive
•Optimize the posture and technique while working
7. 3. Wireless keyboard
● No Physical connection to computer (wire)
● Uses
● Bluetooth
● InfraRed (IR)
4. Virtual Keyboard
● Software
● Keyboard displayed on screen
● Controlled by Mouse / wire touch screen
10. 2.1.2 Mouse
• Control the Movement of the cursor on Display
• MOUSE – Mechanically Operated User Serial Engine
• Pointing Device
• Small device navigate on Flat Surface
• Contain Ball/IR rays inside touches the pad through hole at bottom
Two Types
• Mechanical – Not accurate (Rubber Ball)
• Optical – Accurate (Laser)
11.
12. 2.1.3 Joystick
•Stick Pivots on base reports its angle and direction
•Moves in all Four Direction
•Used in
❏ Games
❏ Cranes
❏ Underwater Unmanned Vehicles
❏ Surveillance Camara
•
13. 2.1.4 Optical Mark Reading and Recognition (OMR )
❖ Reads Pencil Marks and convert into digital form
❖ Pre printed forms are designed with box
❖ Dark Ink or Pencil to fill
❖ Read by Reader
❖ Used in Objective type of answer papers for evaluation
14. 2.1.4 OCR Optical Character Recognition
❏ Recognises Alphabetic and Numeric
❏ No special Inc required
❏ Can be edited (Width, Height, Depth)
❏ Used in Credit card Billing, Large Post Office(PIN CODE) to sort
geographically
15. 2.1.4 MICR (Magnetic Ink Character Recognition)
❏ Shape of the character recognised by the magnetic charge
❏ Used in Bank to Process Cheque
❏ Eliminates manual error
❏ Save Time
❏ Increases Accuracy
16. 2.2 Introduction to Output devices
● Result/Information
● After Processing
● O/P must be human understandable format
Most Commonly Used
○ Monitors
○ Printers
17. 2.2.1 Monitor
● Used output device
● Also called as Display screen / Visual display unit(VDU)
● VDU = Display of data
● Monitors are connected with the computer
18. ● The smallest dot = pixel
● Increase in the no of pixel = Increase in Resolution
● Resolution = Quality of Display
● 640x480, 1024x768
● Size is Measured Diagonally 12",14",17",19", 21"
19. Printer
● Prints text / Images on paper or other media
● Print = Hard copy’
Types (Speed & Quality)
1. Impact printers - Striking device against Inked Ribbon
2. Non-impact printers
20. Characteristics of impact printers
● Physical contact with the paper
● Multiple copies = Carbon = Many layers of paper
● Very noisy (1)
● Slow
● No Transparencies
● Speed = Characters per seconds (cps)
21. Characteristics of Non-impact printers
● Uses ink or semi-solid ink
● Both cartridge and flow of ink is controlled by the processors
● Faster, Different colour/font/size
● Noiseless
● High-quality graphics
● Support the transparencies
22. ● No impact on paper
● Measured in dots per inches (dpi)
● Speed = Number of pages per minute (ppm)
● The size of the printing various A4, A3, A2, A0 and Jumbo size
23. Line Printer
● High-speed printers (One line at a time)
● Print 150 lines to 3000 lines/min
● Supports for only one font
● No Graphics
● Low quality
● Noisy to operate
● Print large volume
24. Dot Matrix Printer
● Most popular serial printer is the dot matrix printer
● It prints one line of 8 or 14 points at a time
● Print head moves across a line
● Slow
● Speed 300 characters per second
○ VRL (Booking Ticket
○ Parcel Booking reciept
25. Thermal Printer
● Electrically heated pins against special heat-sensitive paper
● Inexpensive
● Fax machines
● Darken over time (sunlight and heat)
● Fade after a week or two
● Poor quality print.
26. Laser Printers
● Use a laser beam and dry powdered ink
● Ggood Quality of graphic images
● Quality = dots per inch (dpi)
● Resolutions range from 300 dpi to 1200 dpi
27. Inkjet Printers
❏ Uses colour cartridges which combine magenta, yellow and cyan,black inks to create
colour tones
❏ Spraying ionizing ink at paper
❏ Magnetized plates in the ink’s path direct the ink onto the paper in the described shape
28. 2.2.2.8 Plotter Printers
❏ Draw lines using a pen
❏ Draw continuous lines
❏ Multicolor plotters use different-colored pens
❏ More expensive than printers
❏ Used in engineering applications
29. 2.2.3 Speakers
Analog/digital => audible frequency in the speaker => Voice output (audio data)
speech synthesizer => voice output
Used in many places like
airlines, banks, automatic telephone enquiry system, music/ songs
30. 2.3 Introduction to Memory devices
❏ Essential part of the computer
❏ Storage part of the computer
❏ Memory = Main memory
❏ For Future Use
❏ Storage = Large Volume (Hard Disc)
Two Types
1. Primary memory
2. Secondary memory
33. There are different types of memories:
1. Read Only Memory (ROM)
2. Programmable Read-Only Memory (PROM)
3. Erasable Programmable Read-Only Memory (EPROM)
4. Electrically Erasable Programmable Read-Only Memory (EEPROM)
34. Read Only Memory
Burnt (pre-recorded) at manufacturing time
Once data written into a ROM chip cannot be erased
Data stored permanently (non volatile)
35. Programmable Read Only Memory - PROM
Written only once
Not burnt at the manufacturing time
Programmed using PROM programmer or a PROM burner
PROM is also a non-volatile memory
36. Erasable Programmable Read Only Memory – EPROM
❏ Erased and re-programmed using a special PROM programmer
❏ non-volatile memory
❏ Ultraviolet light is used to erase the contents of the EPROM
37. Electrically Erasable Programmable Read Only Memory – EEPROM
❏ Similar to EPROM
❏ Data erased by exposing it to an electrical charge
❏ Non-volatile
❏ Not as fast as RAM or other types of ROM
38. Random Access Memory - RAM
❏ Most common type of memory found in the modern computers
❏ Main store = Program gets stored temporary
❏ CPU fetches program instructions from the RAM
❏ CPU store results stores in RAM
❏ Switch OFF a computer Data gets erased
❏ Volatile
39.
40. 2.3.2 Secondary Memory
● Computer need to store data programs
● Primary memory is volatile =>Secondary storage
● Non Volatile
● Large amount of data storage for long period of time
● Example
○ hard disks
○ Magnetic tapes
○ Floppy disks
○ CD-ROM
41. ○ The average time required to reach a storage location and obtain its
contents is called its access time
○ Access time = Seek time + Transfer time
42. Hard Disk
❏ Its is magnetic disk on which you can store computer data
❏ Direct-access storage medium
❏ Store data randomly
❏ High speed rotating surfaces coated with a magnetic recording medium
❏ Write Head
❏ Read Head
❏ Each ring(called a track)
❏ Track Divided into a number of sectors Data elements (bytes or characters)
43.
44. ● The smallest unit read/write in disk is a sector
● Storage capacity of the disk = Number of tracks * number of sectors *
bytes per sector * number of read/write heads
● Disk rotation speed 80,000 rpm
45. Magnetic Tape
● Thin tape with a coating of a fine magnetic strip (plastic)
● Bits recorded as magnetic spots on the tape, several tracks
● 7 - 9 bits recorded simultaneously
● Read/write heads are mounted one in each track
46. Floppy Disk
● Thin circular disk
● Soft magnetic disk
● Flexible or semi-rigid protective jacket
● Rotation speed 360rpm
● read/write head makes physical contact with disk
● 3.5" in size
● Hold 1.44 MB of data
● ‘write protected’
● Slower to access than hard disks
● Less storage capacity
● Less expensive and is portable
● It can be accessed randomly.
47. ● Optical Disk
● Data can be read
● Written by lasers
● Random access storage medium (Can be easily read from any point on the disk)
● CD-ROM = Compact Disk - Read Only Memory
48.
49. DVD
● Digital Video Disc
● Advances in optical disc technology
● Stores Music, Data
● Digital Versatile Disc
50. BLUE ray disk
● BD
● Thickness of 1.1mm
● Recording capacity 23.3GB/25GB/27GBa
51. Portable storage device (PSD)
● Small hard drive
● Fixed size hard drives of 256GB, 320GB,500Gb,1Tb,2Tb etc
● Expandable to unlimited storage capacity
52. 2.3.3 Cache Memory
● Small amount of high-speed memory
● Between primary memory and CPU (processor)
● Two levels L1 and L2
○ L1 present inside CPU
○ L2 present on mother board
○ Holds the most recent data/instructions
