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LPT
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For other uses, see LPT (disambiguation).
| It has been suggested that this article or section be merged with Parallelport. (Discuss) Proposed since February 2012. |

LPT pinout
LPT (Line Print Terminal or Local Print Terminal) is the original, and still common, name of the parallel port interface on IBMPC-compatible computers. It was designed to operate a text printer that used IBM's 8-bit extended ASCII character set. The name derives from the fact that "line printer" was a common generic term at the time forany type of text printer. Graphical printers, along with a host of other devices, have been designed to communicate with the system. It was a de facto industry standard for many years, and was finallystandardized as IEEE 1284 in the late 1990s. Today, the parallel port interface is seeing decreasing use because of the rise of Universal Serial Bus (USB) and FireWire (IEEE 1394) devices; along withnetwork printing using Ethernet.
Contents * 1 History * 2 Naming * 3 Pinout * 4 Etymology * 5 See also |
History
Most PC-compatible systems in the 1980s and 1990s had one or two ports,with communication interfaces defined like this:
* LPT1: I/O port 0x378, IRQ 7 (usually in monochrome graphics adapters, dedicated IO cards in color systems, or using a controller built into themainboard)
* LPT2: I/O port 0x278, IRQ 5 (usually in serial port controller, or the stand-alone IBM Printer adapter)
Some systems also had an LPT3 port, but this was less-consistently defined,generally sharing the LPT1 interrupt despite having its own IO address (i.e. only one could be used at a time). In reality, computers rarely have more than one LPT port.
A wide variety of devices wereeventually designed to operate on a parallel port. Most were uni-directional (one-way) devices, only meant to respond to information sent from the PC. However, some devices such as Zip drives were...