Text consists of characters (letters, numbers, punctuation marks, or any other symbol requiring one byte of computer storage space) that are used to create words, sentences, and paragraphs.
Graphics are digital representations of nontext information such as drawings, charts, photographs, and animation (a series of still images in rapid sequence that gives the illusion of motion).
Audio is music, speech, or any other sound.
Video consists of images played back at speeds to provide the appearance of full motion.
2. The characteristics of LCD monitors, LCD screens, plasma monitors, and HDTVs.
LCD's Over the last decade, the display of choice has been the monochrome character liquid crystal display (or LCD display as it is commonly referred to, despite the grammatical error). The format of two lines of sixteen characters has become the norm, despite many other variants. This format has become so popular that in most cases smaller LCD displays are actually more expensive, simply due to the economics of supply – LCDs in the 2 × 16 format are manufactured in such large quantities that the manufacturing cost is much lower than those for simpler displays. This lower manufacturing cost is reflected in the price we pay for the component, even when purchasing just one.
The popularity of the 2 × 16 character LCD is such that many manufacturers produce their own displays with a compatible interface. In many cases, displays from different manufacturers are indistinguishable from each other and this makes the designer’s life much easier. There is nothing worse than writing a constructional article using some specialist component, only to fi nd the sole manufacturer has stopped making it by the time your article is published! These LCD displays all bear the same characteristics. The display area is arranged as 32-character cells. Each cell is a uniform array of 35 small dots, arranged in a grid fi ve wide by seven tall.
The LCD display is mounted on a small PCB that contains one or two ICs which provide the interface (control) between the display itself and your microcontroller. A small read only memory (ROM) within the control IC simplifies the means by which you write information onto the display – you specify an ASCII character code, and the controller will draw the corresponding dots in a character cell. The controller IC has a small amount of RAM too, which can be used to display user-generated graphical symbols within a character cell. This is useful for creating icons (a battery symbol for example) but as the display is arranged as a collection of character cells, it is not possible to write in the gaps between characters, and so a full display sized graphical image cannot be produced.These displays have other drawbacks too.
LCD's screen The pixels in LCD panels work by passing polarized light through filter layers. To light up a pixel, the liquid crystal component in each pixel applies a ‘twist’ to the light after it passes through the first polarizing layer, making it able to pass through the second. Unlike CRT displays, where what you see is caused by the phosphor coating inside the glass tube being excited by electron beams, the light emitted from an LCD screen makes its way through multiple layers, channeled out through each pixel. This is the root cause of this technology’s biggest Achilles’ heel: view an LCD screen from straight on and you’ll see each pixel exactly as intended. But view it from far enough to one side - or above or below for that matter - and you won’t get the direct, face-on strength of the light beaming out of the pixels. To use a very crude analogy, it is a little like the difference between viewing a light at the base of a tube from face on or from off to one side. Only one viewpoint gets the full strength of the light as it shines out. The result is changes in the values of what’s shown on the screen depending on where you sit. This is clearly a disaster for colour proofing, and something that no amount of calibration can help.
LCD's screen The pixels in LCD panels work by passing polarized light through filter layers. To light up a pixel, the liquid crystal component in each pixel applies a ‘twist’ to the light after it passes through the first polarizing layer, making it able to pass through the second. Unlike CRT displays, where what you see is caused by the phosphor coating inside the glass tube being excited by electron beams, the light emitted from an LCD screen makes its way through multiple layers, channeled out through each pixel. This is the root cause of this technology’s biggest Achilles’ heel: view an LCD screen from straight on and you’ll see each pixel exactly as intended. But view it from far enough to one side - or above or below for that matter - and you won’t get the direct, face-on strength of the light beaming out of the pixels. To use a very crude analogy, it is a little like the difference between viewing a light at the base of a tube from face on or from off to one side. Only one viewpoint gets the full strength of the light as it shines out. The result is changes in the values of what’s shown on the screen depending on where you sit. This is clearly a disaster for colour proofing, and something that no amount of calibration can help.
Older LCD screens had such a narrow field of view that merely leaning over a bit or just sitting up straight in the chair would produce obvious visual changes. This isn't the case with newer displays, but it is worth noting that if you sit quite close to today’s larger panels your angle of view from one side to the other and from top to bottom can be great enough to produce colour shifts in objects simply though being in different parts of the screen. Although LCD technology is constantly improving, the increase in display sizes tends to make this somewhat of a ‘two steps forward, one step back’ situation, particularly with the very largest LCD panels now on offer.
Plasma displays are bright (1000 lux or higher for the module), have a wide color gamut, and can be produced in fairly large sizes, up to 381 cm (150 inches) diagonally. They have a very low-luminance "dark-room" black level compared to the lighter grey of the unilluminated parts of an LCD screen. The display panel is only about 6 cm (2.5 inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches). Plasma displays use as much power per square meter as a CRT or an AMLCD television. Power consumption varies greatly with picture content, with bright scenes drawing significantly more power than darker ones, as is also true of CRTs. Nominal power rating is typically 400 watts for a 50-inch (127 cm) screen. Post-2006 models consume 220 to 310 watts for a 50-inch (127 cm) display when set to cinema mode. Most screens are set to 'shop' mode by default, which draws at least twice the power (around 500-700 watts) of a 'home' setting of less extreme brightness.
Plasma displays are bright (1000 lux or higher for the module), have a wide color gamut, and can be produced in fairly large sizes, up to 381 cm (150 inches) diagonally. They have a very low-luminance "dark-room" black level compared to the lighter grey of the unilluminated parts of an LCD screen. The display panel is only about 6 cm (2.5 inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches). Plasma displays use as much power per square meter as a CRT or an AMLCD television. Power consumption varies greatly with picture content, with bright scenes drawing significantly more power than darker ones, as is also true of CRTs. Nominal power rating is typically 400 watts for a 50-inch (127 cm) screen. Post-2006 models consume 220 to 310 watts for a 50-inch (127 cm) display when set to cinema mode. Most screens are set to 'shop' mode by default, which draws at least twice the power (around 500-700 watts) of a 'home' setting of less extreme brightness.
The lifetime of the latest generation of plasma displays is estimated at 100,000 hours of actual display time, or 27 years at 10 hours per day. This is the estimated time over which maximum picture brightness degrades to half the original value, not catastrophic failure.
Plasma displays also have their drawbacks. They are often criticized for reflecting more ambient light than LCD displays. The screen is made from glass, which reflects more light than the material used to make an LCD screen, which creates a glare. Although companies such as Panasonic coat their newer plasma screens with an anti-glare filter. Plasma panels currently cannot be made in screen sizes smaller than 32". Although few companies have been able to make plasma EDTVs this small, even fewer have made 32" plasma HDTVs. The 32" screen size is also "going extinct". Plasma displays are also considered bulky and thick (usually six inches in depth) compared to their LCD conterparts. Although 2009 high-end displays, such as Panasonic's Z1 and Samsung's B860 series can as slim as one inch thick. Plamsa displays also tend to consume more electricity than LCD displays. Panasonic, aims to solve this dilema by using Neo-PDP screens for their 2009 series of Viera plasma HDTVs. Panasonic states that the PDPs will consume half the power of the previous series to achive the same overall brightness.
Competing displays include the CRT, OLED, AMLCD, DLP, SED-tv, and field emission flat panel displays. Advantages of plasma display technology are that a large, very thin screen can be produced, and that the image is very bright and has a wide viewing angle. The viewing angle characteristics of plasma displays and flat-face CRTs are essentially the same, topping all LCD displays, which have a reduced viewing angle in at least one direction. Plasma TVs also do not exhibit an image blur common in many LCD TVs.
HDTV's Aside from the specific technical features already listed, there are some standard characteristics that can be compared between any two HDTVs. These all figure into how accurately your HDTV will reproduce the picture from various sources. At the end of the day the important thing is comparing different TVs with your own eyes. Each has a unique set of strengths and weaknesses, and the best picture for you is always subjective, determined largely by which imperfections bother you the most.
Traditional LCD displays aren't very good at reproducing very dark colors because there's always light behind evey pixel. This can be mostly eliminated by LED backlighting, although right now that's only available on high end LCD HDTVs. DLP and plasma HDTVs don't generally have any problems in this area. HDTV's Aside from the specific technical features already listed, there are some standard characteristics that can be compared between any two HDTVs. These all figure into how accurately your HDTV will reproduce the picture from various sources. At the end of the day the important thing is comparing different TVs with your own eyes. Each has a unique set of strengths and weaknesses, and the best picture for you is always subjective, determined largely by which imperfections bother you the most.
Just as a HDTV should produce dark blacks, it should also produce bright whites. Even though LCDs are generally not as bright as DLP or plasma HDTVs, they may seem brighter due to their high color saturation.
How much brighter the whitest white is than the blackest black is a huge component of accurate color reproduction. Your eye is much more sensitive to changes in brightness than in hue (color variation). If you want good color you have to start with correct brightness, and correct contrast assures each step from completely dark to full brightness is also correct. Poor contrast can result in either washed out color in very bright video or loss of detail in dark areas. Due to the combination of factors that go into black level and brightness, DLP HDTVs have varying contrast, largely determined by the quality of their color wheel. This is where plasma excels due to its combination of good black levels and brightness, generally resulting in the best contrast.
The picture displayed on a HDTV may be processed in a number of ways before getting being displayed. It can be sharpened, which can make edges crisp but also create jagged lines in place of smooth edges. Smoothing can reduce jagged edges at the expense of a certain amount of detail. Neither is objectively superior, so you'll have to judge for yourself what makes a good picture. Just be aware that even with the same underlying technology and resolution, two HDTVs can have vastly different pictures.
3. What are the components inside the systems units.
PSU is a part of a computer that supplies power to the rest of the computer. A cord is plugged into the wall that leads to the Out side of the computer and is plugged into the PSU.
Motherboard: The main circuit board in system unit is called the motherboard, it contains adaptor cards processor and memory chips. The mother can also be called the system board.
Chip: A chip is a small semi-conducting material where intergrated circuits can be etched. Integrated circuits have many microscopic pathways capable of carrying electric current. Chips are packed in a certain way so they can be connected to a circiut board.
Central processing unit (CPU): The CPU carries and interprets basic instructions that can operate a computer. The control unit coordinates operations in a computer. The Arithmetic logic unit (ALU) does arithmetic, comparison and logical operations. This can also be known as the processor.
Machine cycle: The machine cycle is the name of the four operations of the CPU. The first step is to 'fetch' the program instuction/data from the memory. The second step is to 'decode', which means translate the instruction into instructions. Step three is to 'execute', carry out the instruction. Finally step four is to 'store', write the result back to memory.
4. The components of a processor and how they complete a machine cycle.
5. Define a bit and describe how a series of bits represents data.
6. Identify the categories of application software.
7. Identify the key features of widely used business programs.
8. What are the advantages of using application software on the Web.
9. History of the Internet.
10. What are diferent storage devices.
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