Paper printer as different from common office laser printer, in fact, has been widely used in many occasions, such as shopping malls supermarkets to print receipts, invoices, and the print the VAT invoice for the company's financial printer, etc. , there are a lot of USES: such as the traffic police at the scene of a ticket with portable paper printers, financial check printer. In order to meet the needs of different printing environment, paper printer interface type has very rich, different printers have parallel, serial port, so, for the user to choose USB port, but we are all very easy to overlook these small the effects of interface on the office efficiency and cost. Now let's take a look at what is the difference between these interfaces. Parallel port is also known as parallel interface. At present computer basically equipped with parallel port, parallel interface mainly as a printer port, use the 25 needles D shape connector. Parallel, refers to the 8 bits of data at the same time through the parallel line transmission, so data transmission speed is greatly increased, but the parallel transmission line length is limited, because the length increases, the interference will increase, the data are easy to get wrong, and does not apply to separate kitchen and other printing equipment and computer printing environment. A serial port is called a serial interface, the PC now generally has two serial COM and COM 1 2. Serial port is different from the parallel port in its data and control information is sent one by one,. Though this speed will be slower, but longer transmission distance is parallel port, so if you want to for a long distance communication, serial port should be used. Usually COM1 is using a 9 pin D type connector, also known as RS - 232 interface COM2 some use is old-fashioned DB25 pin connector, also known as RS - 422 interface, this interface is now rarely used. Compared with the parallel interface of bulky clumsy, now the common square on the printer USB interface is small and exquisite, USB interface has the characteristics of wide application, can be hot plug. Is a user in the use of an external device, don't need to turn it off again on such action, but in front of the computer at work, can be used directly to the USB plug in. But there are also people who believe that compared with the parallel port inspection after long time practice, the stability of the USB interface needs to be improved.