Facsimile fax machine transmits and receives documents over telephone line. The document may contain text, images or hand – written contests. Fax machine at sending side scans the document. It converts it into digital form and then transmits. The fax machine at receiving side converts this digital form into its original form and pints it.
Types of Fax Machines
There are two types of fax machines:
1. Dedicated Fax Machine
It is a normal fax machine. It can send information to another fax machine. It can also receive information from another fax machine.
2. Fax Modem
It is a circuit board inside the system unit. It can send and receive information to and from another computer. It can also send information to a fax machine.
27 Explain the function of imaging system.
Image scanner is also called graphic scanner. It is used to convert text, drawing and photographs into digital form and store it in computer system.
The image scanner scans color or black & white image with light. It then breaks the image into light and dark dots or color dots. Finally, it converts them to digital form. It is also called raster graphics. Raster graphics is a technique to represent image as matrix of dots.
28 Discuss different audio and video input devices.
Different audio and video input devices are as follows:
Audio Input
The process of entering any sound into the computer is called audio input. It may include speech and music etc. audio can be entered through microphone. Audio input devices record the analog sound and convert it into digital form for further processing. The main use of audio input devices is to provide digital input for multimedia computer.
Video Input
The process of entering full – motion recording into a computer is called video input or video capture. Video can be entered from an analog device like VCR. The analog signals of video must be converted into digital form before storing it in the computer. An expansion card converts the analog video signal into digital signal. It is known as video capture card.
Two types of video card are as follows:
• Frame – grabber video card: It can capture and convert a single video frame at a time into digital form. An image of a video at a specific time is called frame.
• Full motion video card: It is also called adapters. It can convert analog to digital signal at the rate of up to 30 frames per second. It gives the effect of a motion picture.
29 Write a short note on digital camera.
Digital camera is an input device. It stores images digitally in its memory rather than recording on film. The pictures taken with a digital camera can be transferred to a computer system. Many digital cameras allow the user to edit the images. The number of digital photos depends on the amount of memory in camera. The main advantage of digital cameras is that making photos is inexpensive and fast. It does not require any film processing.
Most digital cameras store images in internal flash memory. They can also store additional images on mobile storage media like flash memory cards, memory sticks and mini disks etc.
30 What is output? What are different types of output? Name different types of output devices.
Output
The data that has been processed into useful information is called output. The output is of two types:
• Soft Copy Output: The output shown on display screen is called softcopy output. Softcopy output is not tangible. It means that it cannot be touched.
• Hard Copy Output: The output printed on paper is called hardcopy output. The common devices to produce hardcopy output are printers and plotters.
Output Devices
The hardware components that are used to receive information from the computer are called output devices. Output devices take information from the computer and convert it in a form that is understandable by the users.
Examples
Some important output devices are as follows:
• Monitors
• Printers
• Plotters
• Speakers
31 What is difference between soft copy and hard copy
The difference between soft copy and hard copy is as follows:
|
Soft Copy |
Hard Copy |
| 1. Soft copy is in electronic form. | 1. Hard copy is in printed form. |
| 2. It is easier to modify. | 2. It is difficult to modify. |
| 3. It is intangible. | 3. It is tangible. |
| 4. It is stored on storage devices. | 4. It is printed on papers. |
| 5. Its duplicate copies can be produced without any cost. | 5. Its duplicate copies can be produced with cost. |
32 What is difference between input and output devices?
The difference between input and output devices is as follows:
|
Input Devices |
Output Devices |
| 1. Input devices give data and instructions to the computer. | 1.Output devices get information from the computer. |
| 2. Input devices take data and instructions from the user and convert it in a form that is understandable by the computer. | 2. Output devices take information from the computer and convert it in a form that is understandable by the users. |
| 3. Examples of input devices are keyboard and mouse. | 3.Examples of output devices are monitor and printer. |