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MONITORS,VGA,SVGA
Monitor Overview The most-used output device on a
computer. Most desktop displays use a cathode ray
tube (CRT). Laptops use liquid crystal display (LCD),
light-emitting diode (LED), and gas plasma or other image projection technology.
Monitors using LCD technologies are beginning to replace CRT.
What is Being Used Today? The most popular display today remains
CRT. It has been available for more than 70
years. CRTs:
1. Vivid colors and detailed images and text.
2. Cost less than LCD monitors. 3. Continue to evolve.
Monitor Specifications Monitor Specifications can be judged
through, Size Resolution Refresh rate Dot pitch
Size A monitor’s size affect how well we can see
images. With a larger monitor, we can make the objects
on the screen appear bigger. Monitors are measured diagonally, in inches,
across the front of the screen. A 17 inch monitor measures 17 inches from the
lower left to the upper right corner. CRT monitors viewing area is smaller than the
monitor’s overall size.
Resolution The images you see on your monitor are made of
tiny dots called pixels. The term resolution refers to the sharpness and
clarity of an image. A monitor resolution is determined by the
number of pixels on the screen. It is expressed as a Matrix.
The more pixels a monitor displays, higher will be its resolution. Clearer will be images appear.
Quality
Manufacturers describe quality by dot pitch.
Smaller dot pitches mean pixels are closely spaced which will yield a sharper image.
Most monitors have dot pitches that range from 0.22mm to 0.39mm.
From CRT to LCD CRT
Bulky, heavy, use vacuum tube technology.
Using technology that was developed in the 19th century.
LCD First LCD laptop monitors
were very small due to manufacturing costs.
Light, sleek, energy-efficient, have sharp picture.
How Monitors Work
Most use a cathode-ray tube as a display device.
CRT: Glass tube that is narrow at one end and opens to a flat screen at the other end.
Narrow end contains electron guns.
Monitor Classifications Monochrome: Display two colors, one for the
background and one for the foreground.
Gray-Scale: A special type of monochrome monitor capable of displaying different shades of gray.
Color: Can display anywhere from 16 to over 1 million different colors. Sometimes called RGB monitors.
IBM Advances inDisplay Technology
In 1981, IBM introduced the Color Graphics Adapter (CGA) display, able to display 4 colors and max resolution of 320x200.
In 1984, Enhanced Graphics Adapter (EGA) display, able to display 16 colors and resolution of 640x350.
IBM Advances in Display Technology (cont.)
In 1987, Video Graphics Array (VGA) display. Most computers today support the VGA
standard.
In 1990, Extended Graphics Array (XGA) display, capable of resolutions 800x600 in true color ( 16.8 million colors) and 1024x768 in 65,536 colors.
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VGA VGA = Video Graphics Array Introduced by IBM in 1987, still using
today All points addressable Transmitting analog signal
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VGA Specifications 256 kB Video RAM 16-color and 256-color paletted display modes. Selectable 25.175 MHz or 28.322 MHz master
clock Maximum of 800 horizontal pixels Maximum of 600 lines Refresh rates at up to 70 Hz (Usually 60 Hz) Vertical blank interrupt Planar mode: up to 16 colors (4-bit planes) Packed-pixel mode: 256 colors (Mode 13h)
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SVGA
Short for Super Video Graphics Array, SVGA is a set of video standards one step above VGA. SVGA monitors are capable of displaying up to 16 million colors with a resolution of 800 x 600 on 14 inch monitors and up to a 1200 x 1600 resolution on a 20 inch. The picture shows what the typical VGA/SVGA connection. Today, SVGA is being phased out by the connection knowns as DVI.
SVGA
The output of both the SVGA and VGA card is analog; however, the internal calculations which the card performs in orderto come to the output voltages are all digital. There is no change necessary to increase the number of colors an SVGA display system can reproduce; however, the video card must be able handle much larger numbers, and might need to be redesigned.
Difference Between VGA &SVGA 1. SVGA is an extended version of the
VGA; VGA is now an outdated computer display hardware which was the standard by which the majority of PC clone manufacturers conformed.
2. SVGA has an upward resolution of 1024 x 768 eight bit pixels; VGA has a 16 color or 256 color mode .