Printers
Printers are the most commonly used output device. They are used to print output on the paper. The output may be in the form of characters, symbols and graphics information printed on paper is called hardcopy
Categories/Types of Printers
Printers are classified into two main acategories or types:
1- Impact Printers
2- Non-Impact Printers
Impact Printers
The types of printers that produce output on paper by striking the print hammer or wheel against an inked ribbon are called impact printers. impact printers work like typewriter. They can print characters and graphics on the paper
Impact printers are slower in printing and produce low quality output. The printing speed of these printers is measured in characters or lines per minute. They also produce more noise during printing. Today they are not commonly used.
The examples of impact printers are :
1- Dot matrix printer
2- Daisy Wheel printer
3- Line printer
Dot Matrix Printers
A dot matrix printers is an impact character printer. It makes a hardcopy by printing one character at a time. Its printing speed is from 200 to 1000 or more characters per minute.
Dot matrix printer contains a print-head with a matrix of small pins arranged in rows and columns. Dot matrix printer produces output on paper by striking pins against an ink ribbon. Usually, a dot matrix printer uses 100 to 300 dots per inch (DPI) to print output on the paper. Print-heads are avialable with 9, 18 or 24 pins. The dot matrix printer with 24-pins provides best quality printout.
Dot matrix printers are usedd with personal computer. They are less expensive. The printout quality of these printers is not bad. They also produce more noise during printing.
Daisy Wheel Printer
Daisy wheel printer is also an impact character printer. It is similar to typewriter. It has a print wheel with a series of petals. This wheel is known as daisy wheel. Each petal of dasiy wheel contains a character at its end. A motor rotates the wheel. When the desired character reaches at the print position on the paper, a hammer strikes a petal against the ribbon. In this way, a character is printed on the paper. This printer is slower than dot-matrix printer. However, its print quality is better than dot matrix printer
Line Printer
Line printer is an impact printer. it is very fast printer. It prints a complete line of characters at a time. The printing speed of line printer is measured in lines per minute (lpm). It is upto 3000 lines per minute.
Line printers are normally used with mainframe and mini computers.
Two types of line printers are ;
1- Chain Printer
2- Band Printer
