> 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/npx.4.md).

# npx.4

`npx` — 数值处理扩展协处理器

## 名称

`npx`

## 概要

`device npx hint.npx.0.at="nexus" hint.npx.0.port="0x0F0" hint.npx.0.flags="0x0" hint.npx.0.irq="13"`

## 描述

`npx` 驱动启用系统数值处理扩展协处理器的使用。数值处理扩展存在于具有 486DX CPU 的系统和具有 387 或 487SX 协处理器的系统中。`npx` 驱动是系统正常运行所必需的。如果系统中没有 NPX，系统将无法引导。

`npx0` 的标志为：

**0x01** 不使用 NPX 寄存器来优化 bcopy。 **0x02** 不使用 NPX 寄存器来优化 bzero。 **0x04** 不使用 NPX 寄存器来优化 copyin 或 copyout。

当满足以下所有条件时，通常使用 NPX 寄存器来优化复制和清零：

* `cpu I586_CPU` 是一个选项
* CPU 是 i586（可能不是 Pentium）
* `npx0` 的探测成功
* INT 16 异常处理工作正常。

此时使用 NPX 寄存器进行复制和清零通常快 30-100%。

这些标志可用于控制不工作或较慢的情况。在引导时使用 hints 设置它们能正确工作（在引导过程的后期 `npx0` 附加之前不使用优化）。

## 缺陷

存在很多缺陷，尤其是在旧的主板上。特别是，某些主板没有正确连接从 NPX 到 CPU 的中断线。


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