> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man4/lpt.4.md).

# lpt.4

`lpt` — 通用打印机设备驱动

## 名称

`lpt`

## 概要

`device ppc device ppbus device lpt`

## 描述

当前的 *lpt* 驱动是原始 lpt 驱动向 [ppbus(4)](/man/man4/ppbus.4.md) 系统的移植。

此次移植的一个目的是允许与其他并行设备共享并行端口。其次，inb()/outb() 调用已被 ppbus 函数调用取代。得益于 ppbus 接口，lpt 现在与架构无关。有关 ppbus 系统的更多信息，请参见 [ppbus(4)](/man/man4/ppbus.4.md)。

打开打印机设备时，lpt 会分配并行端口总线，仅在传输完成时释放：即设备关闭时，或在中断驱动模式下整个缓冲区发送完毕时。

驱动可配置为中断驱动或轮询打印机。配置为中断驱动的端口可使用 lptcontrol(8) 命令切换到轮询模式。

根据硬件情况，可使用 lptcontrol(8) 命令配置扩展功能。对于 ECP/ISA 端口，可利用 FIFO 和 DMA。

要从 /dev/lpt0 获取打印机信息，只需对设备应用 `cat` 命令。如果打印机支持 IEEE1284 半字节模式且有数据要发送给主机，你将获取到这些数据。

## 文件

**`/dev/lpt0`** 第一个并行端口驱动

## 参见

[ppbus(4)](/man/man4/ppbus.4.md), [ppc(4)](/man/man4/ppc.4.md), lptcontrol(8)

## 历史

此驱动取代了现已废弃的 lpa 驱动的功能。

## 缺陷

缺陷很多，尤其是在廉价的并行端口实现中。

只有当打印机已连接并在线时才能打开 lpt 端口，这使得没有连接打印机时无法运行 lptcontrol(8)。

此驱动仍有重写的空间。


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