Class 11 Computer Science (SLO Based) Notes For the Examination 2024 and onwards under the Federal Board of Intermediate and Secondary Education (FBISE), Islamabad, Punjab Boards, Rawalpindi, Lahore, Karachi board, etc., and All other boards in Pakistan and abroad.
Unit-1
Unit-1
"Introduction to Computers"
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1. Short Response Questions and Answers:
Q51. What are the functions of the Barcode reader?
Ans:
Barcode reader:
- It scans bar code or UPC (Universal Product Code) on products.
- The barcode has information about the product like expiry date, price, etc.
- This information is given to computers for generating bills which makes faster checkouts.
- It scans bar code or UPC (Universal Product Code) on products.
- The barcode has information about the product like expiry date, price, etc.
- This information is given to computers for generating bills which makes faster checkouts.
Q52. What are the functions of the Magnetic Strip Card Reader?
Ans:
Magnetic Strip Card Reader:
- It reads information on a magnetic strip located on a plastic card.
- Information is stored in the form of magnetized spots.
- Information can be read by swiping the cards on the reader.
Examples: ATM cards, credit cards, driving licenses, etc.
Output Devices:Output devices display useful information.
Types of Output Devices:
Softcopy output: It is displayed on a screen in the form of text, images, video, etc.
Hardcopy output: It is in printed form on paper by a printer or plotter.
Sound output: sound output generated through speakers in the form of sound.
Monitor:
- Also called VDU( Video Display Unit)
- It produces soft copy output. (text, graphics, video, animations, etc.)
Features:
- Size: monitor varies in size from 15 to 21 inches.
- Colour: monitor can be black and white or RGB (colored).
- Pixel: stands for picture element. It is a small dot on the monitor forming an image.
- Resolution: numbers of pixels per square inch. Higher the resolution better the image quality.
- Dot pitch. Distance between two pixels on the screen. Lesser dot pitch means higher resolution.
Types of monitor:
CRT, LCD, LED, etc.
CRT (Cathode Ray Tube) Monitors.
- Similar to standard television sets.
- Heavier and consumes more power.
- It is a vacuum tube having an electron gun and a phosphor-coated screen.
- An electron gun sprays a beam of electrons which glows the phosphor-coated screen when striking it.
- Colored monitors have three electron guns and phosphor atoms (Red, Green, and Blue) RGB.
- The remaining colors are produced by the combination of Red, green, and blue.
LCD (Liquid Crystal Display):
- It is thin and lightweight.
- They have better resolution and emit less radiation than CRT.
- They are portable, less expensive, reliable, and less harmful to the eyes than CRT.
- It has a fluid-like substance called liquid crystal between two sheets.
- These molecules are lined up on the screen and have two states.
- either they allow or block the light to produce images on screen.
- They are used in, laptops, monitors, phones, clocks, etc.
LED (Light Emitting Diode):
- It uses LED (Light Emitting Diode) as pixels.
- Lighter in weight and consume less power than LCD.
- Better resolution and emit less radiation.
- Long-lasting and reliable.
- Expensive than other monitors
Printers:
- Produce hardcopy output.
- Connected to computers through parallel or USB ports.
- Print quality, print speed, printing graphics.
Types of Printers:
- Impact printers
- Non-impact printers
Impact printers:
- Work like a typewriter.
- Image is produced when the print head strikes against the paper.
- Impact printers have low print quality
- they produce a lot of noise.
- They are slow and poor ability to print graphics.
Example: Dot matrix and chain printers
Dot matrix Printers:
- The dot matrix has 9 to 24 pins on its print head.
- Its print quality depends upon the number of pins.
- Not very popular nowadays.
Chain printers:
- They are line printers. (can print one line at a time).
- It contains a character on a chain that moves very fast.
- The image is produced when a set of hammers strike against an ink ribbon on paper.
Non-impact printers:
- They produce images without striking the paper.
- They are fast (print an entire page at a time).
- Better print quality than impact
- Produce very less noise while printing.
- Expensive than impact printers.
- Better ability to print graphics.
Examples: laser printers and inkjet printers.
Laser printers:
- Print technology is similar to photocopiers.
- They are very fast and silent.
- Print an entire page at a time.
- Print quality is very high.
- Also, print colored graphics.
Inkjet printers:
- They produce images by spraying tiny drops on ink on paper.
- Less expensive and slower than laser printers.
- Print quality is also less than laser printers.
- Can produce colored prints cheaper than laser printers.
Plotters:
- Produce large-scale hardcopy output.
- Used in architectural drawings, maps, graphs, civil engineering drawings, and panaflexes.
Examples: flatbed plotters and drum plotters.
Flatbed plotters:
• Paper is spread and fixed n rectangular flat surface.
• It has a mechanical arm holding different colored pens.
• Which is moved on the surface to draw the image.
Drum Plotter:
- It has a rotating drum.
- The sheet is fed from one side of the drum.
- The drum rotates to move the paper.
- It produces large-size panaflexes.
Speakers:
- Produce audio output.
- Attached to the sound card on the motherboard.
- Convers electric signals in sound form.
Magnetic Strip Card Reader:
- It reads information on a magnetic strip located on a plastic card.
- Information is stored in the form of magnetized spots.
- Information can be read by swiping the cards on the reader.
Output Devices:
Output devices display useful information.
Types of Output Devices:
Softcopy output: It is displayed on a screen in the form of text, images, video, etc.
Hardcopy output: It is in printed form on paper by a printer or plotter.
Sound output: sound output generated through speakers in the form of sound.
Monitor:
- Also called VDU( Video Display Unit)
- It produces soft copy output. (text, graphics, video, animations, etc.)
Features:
- Size: monitor varies in size from 15 to 21 inches.
- Colour: monitor can be black and white or RGB (colored).
- Pixel: stands for picture element. It is a small dot on the monitor forming an image.
- Resolution: numbers of pixels per square inch. Higher the resolution better the image quality.
- Dot pitch. Distance between two pixels on the screen. Lesser dot pitch means higher resolution.
Types of monitor:
CRT, LCD, LED, etc.
CRT (Cathode Ray Tube) Monitors.
- Similar to standard television sets.
- Heavier and consumes more power.
- It is a vacuum tube having an electron gun and a phosphor-coated screen.
- An electron gun sprays a beam of electrons which glows the phosphor-coated screen when striking it.
- Colored monitors have three electron guns and phosphor atoms (Red, Green, and Blue) RGB.
- The remaining colors are produced by the combination of Red, green, and blue.
LCD (Liquid Crystal Display):
- It is thin and lightweight.
- They have better resolution and emit less radiation than CRT.
- They are portable, less expensive, reliable, and less harmful to the eyes than CRT.
- It has a fluid-like substance called liquid crystal between two sheets.
- These molecules are lined up on the screen and have two states.
- either they allow or block the light to produce images on screen.
- They are used in, laptops, monitors, phones, clocks, etc.
LED (Light Emitting Diode):
- It uses LED (Light Emitting Diode) as pixels.
- Lighter in weight and consume less power than LCD.
- Better resolution and emit less radiation.
- Long-lasting and reliable.
- Expensive than other monitors
Printers:
- Produce hardcopy output.
- Connected to computers through parallel or USB ports.
- Print quality, print speed, printing graphics.
Types of Printers:
- Impact printers
- Non-impact printers
Impact printers:
- Work like a typewriter.
- Image is produced when the print head strikes against the paper.
- Impact printers have low print quality
- they produce a lot of noise.
- They are slow and poor ability to print graphics.
Dot matrix Printers:
- The dot matrix has 9 to 24 pins on its print head.
- Its print quality depends upon the number of pins.
- Not very popular nowadays.
Chain printers:
- They are line printers. (can print one line at a time).
- It contains a character on a chain that moves very fast.
- The image is produced when a set of hammers strike against an ink ribbon on paper.
- They produce images without striking the paper.
- They are fast (print an entire page at a time).
- Better print quality than impact
- Produce very less noise while printing.
- Expensive than impact printers.
- Better ability to print graphics.
Laser printers:
- Print technology is similar to photocopiers.
- They are very fast and silent.
- Print an entire page at a time.
- Print quality is very high.
- Also, print colored graphics.
Inkjet printers:
- They produce images by spraying tiny drops on ink on paper.
- Less expensive and slower than laser printers.
- Print quality is also less than laser printers.
- Can produce colored prints cheaper than laser printers.
Plotters:
- Produce large-scale hardcopy output.
- Used in architectural drawings, maps, graphs, civil engineering drawings, and panaflexes.
Examples: flatbed plotters and drum plotters.
Flatbed plotters:
• Paper is spread and fixed n rectangular flat surface.
• It has a mechanical arm holding different colored pens.
• Which is moved on the surface to draw the image.
Drum Plotter:
- It has a rotating drum.
- The sheet is fed from one side of the drum.
- The drum rotates to move the paper.
- It produces large-size panaflexes.
Speakers:
- Produce audio output.
- Attached to the sound card on the motherboard.
- Convers electric signals in sound form.
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Please Select from below 👇👇
Unit-1 (Important Short Q/A)
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Shortcut Links For:
1. 5th Class All Subjects Notes
2. 8th Class All Subjects Notes
1. Website for School and College Level Physics
2. Website for School and College Level Mathematics
3. Website for Single National Curriculum Pakistan - All Subjects Notes
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