May 252012
 

Printer is one of the most important hard copy output devices. Data manipulation, processing and giving relevant information is the main work of computers. They have been designed for doing such works in an accurate and faster way. The monitor is a soft copy. output device (since it cannot be seen when the power of the computer is off). During processing, the output is seen on the monitor. Any kind of data, such as name list, reports, processed data report, unprocessed data report, unprocessed data report etc. can be printed by printer. Various types of printers are available in today’s era of information and technology. We can use the printer according to our requirements. Some printers such as Dot Matrix printers are low speed printers, but the printers like Laser printers are high speed printers. An ordinary printer can print 80 characters wide, whereas the mainframe printers can print 132 characters wide 1000 and 2500 paragraphs. The printers can be classified as impact and non-impact.

While describing about the working method of Impact printer, the head of the printer hits the ribbon and the characters get printed on the paper, but in case of non-impact printer, the ink is sprayed to the paper so that the letter get printed. Laser printer is an example of non-impact printer and Dot-Matrix printer is an example of impact printer.

Some laser printers have very high speed and can even print 132 character; width-wise 64000 paragraphs per minute. Attempts are being made to increase this speed. Mainframe printers are also known as line printers. Printers of microcomputers are: (1) Dot Matrix Printer, (2) Daisy Wheel Printer and (3) Laser Printer (4) Inkjet/Bubblejet Printer.

The printers of microcomputers are also classified on the basis of pins on the head – (i) 9 pins, (ii) 18 pins and (iii) 24 pins. Larger the number of pins, better will be the quality of printed matter and the capacity. The cost of the printers also depends upon their printing speed and capacity.

May 252012
 

The scientific name of crow is Corvus. One of the most amazing creature in this world which can understand the human language. It is also known as one of the most clever bird. Crows are also taken as one of the messenger in the world. The recent research proved that they are the most clever birds which can understand the human language. According  to research, not only the human language, but can also understand the languages of other birds.

Due to this characteristic of the crows, they are easily adopting the densely populated urban areas of different countries. They can also easily search their food and become aware from various threats. According to investigators of such researches, they have recorded the sound of different birds and even the sound of human beings and made them listen. They react differently according to the sounds.

According to the investigators of Vienna University, Austria, crows can also understand the sounds of other birds and also can produce the same types of sounds. As a result of this characteristic, crow can adopt any situation and environment. Similarly, crows can also understand the human emotion like anger, happiness, threats and so on.