LPT3

LPT3 refers to the third parallel printer port on IBM PC-compatible computers. Along with LPT1 and LPT2, it provided a standard 8-bit data channel for connecting printers and other peripherals via the parallel interface, historically common on desktop PCs in the 1980s and 1990s. The port is typically implemented on the motherboard or via an expansion card and includes data, status, and control signals used to manage communication with attached devices.

In terms of addressing, parallel ports are accessed through I/O ports rather than memory addresses. LPT1 is commonly at 0x378, LPT2 at 0x278, and LPT3 at 0x3BC, though exact addresses vary by motherboard, BIOS, and expansion hardware. The port can operate in multiple modes, including Standard Parallel Port (SPP) and enhanced modes such as EPP and ECP, which enable bidirectional or faster data transfer with capable devices.

Software and usage: Operating systems recognize LPT3 as a printer port. In Windows, it may appear as a port named LPT3 and be assigned to a printer driver; in Linux, parallel ports are typically exposed as device nodes such as /dev/lp2 for LPT3 or via the parport subsystem. Modern hardware often lacks a physical LPT3 header, and many new systems do not include parallel port support. Consequently, LPT3 is primarily relevant for legacy printers, industrial equipment, or specialized embedded applications that rely on the IEEE 1284 parallel interface.