Pin printer

Finally, the most unique type of connector is the Centronics connector. The 36-pin Centronics connector is used on your parallel printer cable (one end has a DB-25 connector, the other a 36-pin Centronics connector). 

Dot-matrix printers are the oldest type of printer, as well as the simplest. This type of printer uses an array of pins to strike an inked ribbon, which in turn makes a pattern of dots on the paper. The patterns of dots ultimately form letters and images. Dot-matrix printers are easy to use as well as very inexpensive. However, they are relatively slow and very noisy (as anyone who has tried to talk on the phone while using one can attest). The best dot-matrix printers are only near letter quality (letter quality is the quality found with a typewriter). They are still in use because they are the only printer that can print on carbon copy forms (invoices, receipts, etc.). Because the pins on dot-matrix printers actually strike the paper, they can make simultaneous copies when used with pressure-sensitive forms or carbon paper. 

SCSI devices can be either internal or external to the computer. If they are internal, they use a 50-pin ribbon cable (similar to the 40-pin IDE drive cable). If the devices are external, they use a thick, shielded cable with Centronics-50 or male DB-25 connectors on it. These devices aren t always disk drives. Scanners and some printers also use SCSI because it has a very high data throughput. 

The other type of impact printer we re going to discuss is the dot-matrix printer. These printers work in a manner similar to daisy-wheel printers, except that instead of a spinning, character-imprinted wheel, the printhead contains a row of pins (short sturdy stalks of hard wire). These pins are triggered in patterns that form letters and numbers as the printhead moves across the paper (see Figure 7.2). 

The main disadvantage to dot-matrix printers is their image quality, which can be quite poor compared to the quality produced with a daisy wheel. Dotmatrix printers use patterns of dots to make letters and images, and the early dot-matrix printers used only 9 pins to make those patterns. The output quality of such printers is referred to as draft quality —good mainly for providing your initial text to a correspondent or revisor. Each letter looked fuzzy because the dots were spaced as far as they could be spaced and still be perceived as a letter or image. As more pins were crammed into the printhead... 

A parallel cable consists of a male DB-25 connector that connects to the computer and a male 36-pin Centronics connector that connects to the printer. Most of the cables are shorter than 10 feet long. 

A page description language works just as its name says it does. It describes the whole page being printed by sending commands that describe the text as well as the margins and other settings. The controller in the printer interprets these commands and turns them into laser pulses (or pin strikes). 

Also, with graphics, the commands to draw a shape on the page are relatively complex. For example, to draw a square, the computer (or printer) has to calculate the size of the square and convert that into lots of "strike pin x" (or "turn on laser") and "print nothing" commands. This is where the other types of page description languages come into the picture. 

Which impact printer has a printhead that contains a row of pins that are triggered in patterns that form letters and numbers as the printhead moves across the paper ... 

Centronics parallel interface A standard 36-pin interface in the PC world for the exchange of information between the PC and a peripheral, such as a printer, originally developed by the printer manufacturer Centronics, Inc. The standard defines eight parallel data lines, plus additional lines for status and control information. 

RS-232-C In asynchronous transmissions, a recommended standard interface established by the Electrical Industries Association. The standard defines the specific lines, timing, and signal characteristics used between the computer and the peripheral device and uses a 25-pin or 9-pin DB connector. RS-232-C is used for serial communications between a computer and a peripheral such as a printer, modem, digitizing tablet, or mouse. 

Graphics output can also be sent to a printer or plotter. Most of the cheaper printers are dot matrix printers in which the print head has a series of vertically aligned pins which press through a ribbon onto the paper. In most cases, these pins can be individually manipulated to produce pixel-like raster-ed output. The newer laser printers can produce graphics output of a very high quality, but special software is necessary to define the complex laser path for an entire sheet of paper. 

The more commonly used approach for microarray fabrication is the deposition of pre-synthesized molecules by a microarray printer onto substrate, the so-called contact and nmi-contact microarray printing (Fig. 3a, b). Contact arrayers use different-shaped steel pins for direct deposition of droplets onto the substrate by touching the surface with the pins. Nrai-contact arrayers are similar to commercial piezo-driven ink-jet printers and deposit a droplet onto the substrate without coming into contact with the substrate surface. Microarrayers which use other technical approaches are also commercially available and will also be discussed. 

After retraction of the pin, the fluid film is still intact and fluid is replenished from the ring. Commercially available contact printers are offered, for example, by Genemachines. 

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