Computer Science (SLO Based) Notes
Unit-1
Unit-1
"Introduction to Computers"
************************************
************************************
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.
- Coloured monitors have three electron guns and phosphor atoms (Red, Green, and Blue) RGB.
- The remaining colours 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.
- Coloured monitors have three electron guns and phosphor atoms (Red, Green, and Blue) RGB.
- The remaining colours 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.
************************************
Please Select from below 👇👇
Unit-1 (Important Short Q/A)
************************************
(National Book Foundation - As Federal Textbook Board, Islamabad Based on National Curriculum Pakistan 2026-2027 and Onward prescribed by Federal Board of Intermediate and Secondary Education, Islamabad, and All Pakistan Boards)
(National Book Foundation - As Federal Textbook Board, Islamabad
Based on National Curriculum Pakistan 2026-2027 and Onward prescribed by Federal Board of Intermediate and Secondary Education, Islamabad, and All Pakistan Boards)
0 Comments
Note: Write me in the comments box below for any queries and also Share this information with your class-fellows and friends.