This lecture slide explains the video display components used in the computer system.

1. Repair & Maintenance
D.Com II/II
UNIT 11. VIDEO DISPLAY
LECTURE BY : ER. ASHISH K.C(KHATRI)

2. Introduction:
The graphic card is the piece of hardware that takes the visual output from the processor and
tell the monitor which of the dots (pixels) on the screen to light and to allow users to see it.
The main responsibility of graphic card is to display content in the monitor.
Display card is also called video card.
Responsibility of display card:
- Performance
- Software support
- Reliability and Stability
- Comfort
© ER. ASHISH K.C (KHATRI) 2

3. Video Modes:
There are two types of video modes:
1. Text mode
2. Graphical mode
Text Mode :
In text mode, video information is stored as character in c haracter set.
Usually on PC, the ASCII character determines the text mode.
The video card has built in definition of what the dot shape is for each character, which it uses
to display.
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4. Graphical Mode:
In graphical modes, the dot (pixel) of the screen are manipulated directly, so both text and
image are possible.
The conversion of letters, numbers, etc. to visible image is done by software.
Graphical modes allow for much more flexibility in terms of what is to be displayed on the
screen but at a cost.
Since more memory is required to hold the screen image, the cost also increase.
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5. PC normally boot up in a text mode and display is done in graphical mode after the boot up
process is finish.
In addition to text and graphical mode, the video modes can be define in color and
monochrome mode.
Monochrome monitor are suited for mainly showing text.
Color monitor are most commonly used for color drawings nad grpahics.
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6. Pixel:
Pixel is the smallest controllable element of a picture represented on a screen or paper.
The address of the pixel correspond to it’s physical co-ordinates.
Pixel is a sample of an original images.
More samples typically provides more accurate representation of an original image.
Each pixel of the screen image is displayed on a monitor using a combination of three different
signals; red, green and blue.
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8. Color Depth:
The amount of information that is stored in a pixel determines it’s color depth.
It is also called bit depth because precision of color depth is specified in bits.
The more bits that are use for pixel, the finer or accurate the color detail of an image.
However increase color depth also required significally more memory for storage of the image.
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10. True color is given the name because 3 bit of information are used one for each red, green and
blue signal that make a pixel allowing over 16 million different color.
This allows for realistic representation of color of an image.
True color is necessary for those doing high quality photo editing, graphic design, etc.
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12. Resolution:
The display resolution or display modes is the number of distinct pixels in each dimension that
can be displayed.
It is usually use for pixel count.
Resolution is the number of pixel contained on a display monitor expressed in terms of number
of pixel in horizontal axis into number of pixel in vertical axis.
 Eg: 1024 × 640
© ER. ASHISH K.C (KHATRI) 12

13. Frame buffer memory:
The frame buffer is the video memory that is used to hold the video image displayed on the
screen the amount of memory required to hold the image depend primary on resolution of
screen image and also color depth.
 Memory =
𝑥 𝑟𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 × 𝑦 𝑟𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛×𝑏𝑖𝑡 𝑓𝑜𝑟 𝑝𝑖𝑥𝑒𝑙
8
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14. End of Unit
© ER. ASHISH K.C (KHATRI) 14