What is a Chain Printer?

Chain printer as show in the image bellow. Print characters are contained in a chain, which is moved continuously at a rapid rate by two geared pulleys. Circuitry within the printer senses when the correct character appears at the desired print position on the page. At that point, a hammer strikes the page. This action presses the paper against a ribbon and against the character located at that position. The result leaves an impression of the character. As the chain continues to move transversely across the page, additional characters are printed as they reach the position required by the commands of the computer.

When the requirements of the printed line are fulfilled, the printer carriage control moves the page to the next line position.

The principal of the drum printer as show in the image bellow is very similar to that of the chain printer. All the characters in the specified character set are engraved along circumference of the drum and if 132 print positions are available, this is repeated for each column.

Character printers and line printers are called impact printers because they use electro-mechanical mechanism, which causes the character shape to strike against the paper and leave an image of the character on the paper.