Dot Matrix Printer.

Dot Matrix Printer.


1 - PC sends a series of ASCII codes representing characters, punctuation marks, and moves the printer, such such as tabs, carriage returns and form feeds, which control the position of the print head in relation to
paper.

2 - The ASCII codes are stored in the buffer, a special part of the printer's RAM. The time it uses the matrix
for printing characters is normally greater than the time it takes the PC program and to send these same
characters to the printer, so the buffer helps to release the PC to perform other functions while printing. Generally, the internal buffer of a dot matrix printer has the capacity to store only 7KB to 8KB. When the buffer is full, the printer sends XOFF control code to the computer to stop sending data is suspended. When the buffer frees up space, sending some characters to its processor, the printer sends the control code XON to the PC, releasing sending data.


3 - Enter these codes, there are commands that ask the printer to use a particular table bitmap from a source, located in ROM chips printer. This table tells the printer the model points to be used for
generate the characters represented by ASCII codes.

4 - The printer processor receives the information from the table bitmap of an entire line of type and calculates the most efficient path to the print head has to do. (Some lines need to actually be printed from
right to left.) The processor sends signals that trigger pin print head and also controls movement of the print head and the platen.

5 - The electrical signals are amplified and processor travel through some of the circuits that lead to print head. The print head has by 9 to 24 needles, also called printing pins, aligned vertically. One
ends of each pin connects to a single solenoid or electromagnet. The current coming from the processor activates the solenoid, creating a magnetic field that repels the magnet end of the pin, causing it to move toward the paper.

6 - pin motion plays a ribbon coated with ink. The impact force transfer ink to the paper that is
the other side of the tape. Once the pin is triggered, a spring pulls it back to its original position. The print head 9 continues to activate different combinations of pins print as it moves through the line, so that all
characters consisting of multiple sequences of vertical dots. On some printers, the quality or the bold letter
are made when the print head passes a second time on the same line, a second series of printing dots
displaced.

Source: Evolution of Computers