22_lesson.txt

Today is Sunday on September 10th

lesson 22 page 32 and 33

------------------------

Daisy Wheel
Head is laying  on a wheel and pins corresponding to characters are like petals of Daisy (flower) which is why it is called Daisy Wheel Printer. These printers are generally used for word-processing in offices that require a few letters to be sent there and there with very nice quality.

Advantage
	more reliable than DMP
	better quality
	fonts of character can be easily changed

Disadvantage
	slower than DMP
	noisy
	more expensive than DMP

Line Printers
Line printers are the printers which prints one line at time.

These are of two types:
      drum printer
      chain printers

Drum Printers
This printer is like a drum in shape, hence it is called drum printer. The surface of the drum is divided into a number of tracks. Total tracks are equal to the size of the paper, i.e. for a paper width of 132 characters, drum will have 132 tracks. A character set is embossed on the track. Different character sets (that) available in the market are: 48 character set, 64 and 96 character set. One rotation of drum prints one line. Drum prints are fast in speed can print 300 to 2,000 lines per minute.

Advantage
	very high speed

Disadvantage
	very expensive
	characters fonts cannot be changed

Chain Printer
In this printer, a chain of character sets is used, hence it is called Chain Printer. A standard character set may have 48, 64 or 96 characters.

Advantage
	character fonts can easily be changed
	different languages can be used with the same printer.

Disadvantage
	noisy


*** new vocabulary ***
    petal
    daisy wheel
    drum
    hence
    emboss