Magnetic Drum
It was an early form of primary computer memory. For many machines, a drum formed the main working memory of the machine, with data and programs being loaded on to or off the drum using media such as paper tape or punch cards. Magnetic Drums have become more than obsolete today and it has been replaced by the semiconductor memory.
A drum is a large metal cylinder that is coated on the outside surface with a ferromagnetic recording material akin to the hard disk but with rotating drums instead od rotating platters. A row of read-write heads runs along the long axis of the drum, one for each track.
Historically, Charles Babbage’s printer for hitting characters on the metal plate is regarded as the first printer.
Printers are generally connected to the computer via the parallel LPT port. But these days, the Universal Serial Bus (USB) are rather replacing these ports as the major printer connecting port.
On the basis of printing technology used, printers are generally classified into two types; the impact printers and the non-impact printers. Impact printer use physical hitting on the paper with the typefaces while non-impact printers do not have any physical contact with the paper (The print head of the impact printers make physical contact with the paper while that of non impact do not).
#Some common printers classified
Dot matrix printers: These printers use the matrix of dots on their print head to hit the ink ribbon over the paper to form an image of text. Hence they are impact printers. These printers are not in much use these days because they are slow and noisy. These printers can be seen in use where economical or carbon copy prints are required.
Line Printer: Line printer prints one complete line at a time. It is used for heavy printing applications and can be operated continuously for long time. It has a speed of 300 lpm to 2500 lpm (ie. lines per minute). They are also impact printers.
Drum Printer: A drum printer consists a cylindrical drum which is embossed with characters. It also consists of hammer and carbon ribbon. The drum rotates at a high speed which is striked bt hte hammer to get hard output on the paper. It prints the characters of same font only as the print cylinder is fixed. They are also impact printers.
Laser printers:
These printers can print at a very high speed. They use laser technology together with toner (a type of printer ink) and a light sensitive print drum to produce images or texts on the paper. Obviously, they are non-impact printers.
Inkjet printers: They operate by propelling tying droplet of liquid ink over the paper to reproduce texts or images. These printers have good printing speed and are relatively cheap (but they are not economical because of the high price of the ink and less pages printed per refill kit)
Most modern day printer can print both text and image but printers like Line printer, drum printers can print only characters.
Again, some printers which can print images can only print monochrome images while others can print multi-colour images or texts.
http://img150.imageshack.us/img150/216/msosom6.jpg
Printers and its types
It is a device to produce the hard copy of the documents, images etc stored in the digital form ie the soft copy.Historically, Charles Babbage’s printer for hitting characters on the metal plate is regarded as the first printer.
Printers are generally connected to the computer via the parallel LPT port. But these days, the Universal Serial Bus (USB) are rather replacing these ports as the major printer connecting port.
On the basis of printing technology used, printers are generally classified into two types; the impact printers and the non-impact printers. Impact printer use physical hitting on the paper with the typefaces while non-impact printers do not have any physical contact with the paper (The print head of the impact printers make physical contact with the paper while that of non impact do not).
#Some common printers classified
Dot matrix printers: These printers use the matrix of dots on their print head to hit the ink ribbon over the paper to form an image of text. Hence they are impact printers. These printers are not in much use these days because they are slow and noisy. These printers can be seen in use where economical or carbon copy prints are required.
Line Printer: Line printer prints one complete line at a time. It is used for heavy printing applications and can be operated continuously for long time. It has a speed of 300 lpm to 2500 lpm (ie. lines per minute). They are also impact printers.
Drum Printer: A drum printer consists a cylindrical drum which is embossed with characters. It also consists of hammer and carbon ribbon. The drum rotates at a high speed which is striked bt hte hammer to get hard output on the paper. It prints the characters of same font only as the print cylinder is fixed. They are also impact printers.
Laser printers:
These printers can print at a very high speed. They use laser technology together with toner (a type of printer ink) and a light sensitive print drum to produce images or texts on the paper. Obviously, they are non-impact printers.
Inkjet printers: They operate by propelling tying droplet of liquid ink over the paper to reproduce texts or images. These printers have good printing speed and are relatively cheap (but they are not economical because of the high price of the ink and less pages printed per refill kit)
Most modern day printer can print both text and image but printers like Line printer, drum printers can print only characters.
Again, some printers which can print images can only print monochrome images while others can print multi-colour images or texts.
Differences between magnetic and optical storage
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Differences between SRAM and DRAM
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Difference Between LCD, LED And CRT
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http://img57.imageshack.us/img57/2941/lcdledcrtjm2.jpg
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