Grade 8 -Lesson 2 Cloud Computing and Output devices

Cloud Computing

The practice of storing regularly used computer data (files) on multiple servers (computer) that can be accessed through the Internet. Data is not stored on your personal hard disk. Example, email accounts, dropbox and google drive

You can stop at 5:33!

and

OUTPUT DEVICES

Output devices are equipment used to get information or any other response out of the computer. Examples of output devices are display screens (MONITORS), speakers, multimedia projectors, printers, headphones and plotters.

 

There are two types of output:

1. Softcopy output
2. Hardcopy output

 

Softcopy output is temporary output e.g. information displayed on a screen or in voice or audio form through speakers. This kind of output disappears when the computer is switched off since the screen or the speakers need the computer to work.

Hardcopy output is permanent output e.g. information printed onto paper or film. It is tangible – you can hold it in your hands.

 

Softcopy output devices

Display Screens (Monitors)

Display screens (simply screens) are also called monitors or Visual Display Units (VDU). These are used to output still or moving pictures. There are two types of display screens:

1. Cathode Ray Tubes (CRT): these screens looks like a standard television set.
2. Flat Panel displays: these screens are used mainly with portable computers like laptops, in some desktop computers and even in the latest television sets.

Audio Output Devices

Speakers, headphones and earphones are used to output sound. The quality of the sound depends on the type of system used, the size of the speakers and the computer’s audio card. An audio card is used to process sound in the computer.

Multimedia Projector

A multimedia projector is a compact, high resolution, full-color projector capable of projecting text, images, video and audio content. Multimedia projectors can be connected to computers, VCRs, DVD players and cable boxes. The images transmitted from the device are then transmitted into a special digitized light that is reflected on thousands of mirrors within the projector, which shines the image onto a screen.

 

 

Hardcopy output devices

Printers

A way of classifying printers is as:

1. Impact printers
2. Non-impact printers

Impact printers use a printing mechanism called a print head. They make their output by pressing the print head against a ribbon, which then hits the paper.  The main types of impact printers are dot matrix, daisy wheel and drum, chain or band printers.

Dot matrix printers (character printers)

Characteristics:

• Characters are formed from a matrix of dots.
• The speed is usually  30 – 550 characters per second (cps)
• It is very noisy
• It is relatively fast
• The print obtained is usually poor.
• They are useful for low-quality carbon copy prints or printing on continuous sheets of paper e.g. invoices (bills).
• They are not good for printing shaded graphics or photographs.

 

Daisy wheel printers (character printers)

Characteristics:

• It is very noisy
• Printing is slow (less than 90 cps).
• The text is generally crisp and clean.
• The size and font produced can only be changed by using a different daisy, as the characters on the wheel are fixed.

N.B. This printer is obsolete

Drum, chain or band printer (line printers)

Characteristics:

• They are fast (2500 lines per minute.
• They are used to print large volumes of information.

 

 

Non-impact printers are faster, quieter and produce better quality print than impact printers.  Unlike the impact printer, the printing mechanism makes no contact with the paper. The main types of non-impact printers are laser printers, inkjet printers and thermal printers.

Thermal printers (character printers)

A printer that uses heat to transfer an impression onto paper.

Thermal printers are used in portable calculators, fax machines and some ATMs (automated teller machines).

 

 

Inkjet printers (line printers)

Inkjet printers produce their output by spraying small droplets of ink at high speed into paper, in a pattern. These printers can print in both black-and-white and colour. They used at home and small offices. The print quality is good but not as good as the laser printer. Inkjet printers can also produce both text and graphics. They are cheaper than laser printers.

Laser printers (page printers)

These use a process similar to that of a photocopying machine. They are used in large companies or institutions such as schools. They can also be found in modern offices.   A laser beam and dry powdered ink called toner produces a very fine dot matrix pattern. This pattern is transferred to the page and then fused onto it by heat and pressure. These printers can print in black and white or colour.  These printers can produce more than 40 pages per minute (ppm). The print quality is very good. Laser printers produce both text and graphics. They are very expensive.

Plotters

Plotters use different printing processes e.g. some work like an inkjet printer and others use the same method as laser printers. They are used to produce documents with high quality graphics in a variety of colours e.g. maps, architectural drawings and charts. They can print on large sheets of paper.

 

COM (Computer Output on Microfilm/Microfiche)

COM is a method that is used to store computer documents by reducing them in size to fit on very small photographic sheets of film. They are used to store large volumes of data. These sheets can be read using a special magnifying machine. Microfilm is a roll of film and microfiche is a rectangular sheet of film on which many frames/pages of information can be stored.

 

Games

http://www.teach-ict.com/gcse_new/computer%20systems/output_devices/quiz/hangman_output.htm

http://www.teach-ict.com/gcse_new/computer%20systems/output_devices/quiz/walkplank_output.htm

http://www.teach-ict.com/gcse_new/computer%20systems/output_devices/quiz/matchup_output.htm

References

• Videos adapted from youtube
• https://www.techwalla.com/articles/what-is-a-multimedia-projector
• https://www.merriam-webster.com/dictionary/cloud%20computing
• https://muhammadalijannah.files.wordpress.com/2012/07/output-device.jpg