当人们提到运行本机软件、仿真和软件兼容性时，他们到底指的是什么？请继续阅读本机软件的概念。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户读者Thro**y很好奇以本机方式运行软件意味着什么。他写道：

I’ve been wondering what it means for software to run natively. What exactly is such software and how is it different from software that does not run natively? How can I tell if a given piece of software will run natively on my computer? Is there likely to be software already on my computer that runs natively?

请继续阅读，以获得一个极好的类比，准确地解释在给定系统上原生的含义。

答案

SuperUser contributor Deltik提供了一个奇妙的类比，强调了软件本机的意义，以及在给定系统上可能找到的其他软件类型：

A software is native to a platform if it was designed to run on that platform.

A platform usually refers to an operating system, but it can also be applied to devices such as the Nintendo Game Boy.

Using the Game Boy as an example, it gets its software from cartridges. These cartridges contain code that runs natively on the Game Boy.

Emulators are a layer that allows software designed for one platform to be run on another. For example, there are emulators that can execute images of Game Boy cartridges and allow you to play Game Boy games on your computer or even your mobile phone.

A compatibility layer is kind of like an emulator. When 64-bit computers and operating systems became mainstream, they needed to be compatible with the existing 32-bit technologies. Since 64-bit and 32-bit architectures are very different, a compatibility layer is often needed to run 32-bit software on 64-bit machines. For 64-bit editi*** of Microsoft Windows, Microsoft needed to write a compatibility layer so that 32-bit programs would still work on the new 64-bit system. This is why some programs are often installed to a folder called Program Files (x86), where x86 means “32-bit”.

Compatibility layers tend to be more intimate with the native system than emulators are. VirtualBoxemulates hardware for operating systems*, and the systems that it emulates doesn’t have very much direct interaction with the host system. WoW64 is a compatibility layer in that it lets 32-bit programs run on 64-bit Windows in a more integrated way. WoW64 helps make programs compatible rather thanemulating them in an isolated environment.

A translation library is a component of compatibility layers. Whenever binary code is running non-natively, a translation library helps redirect foreign, non-native calls to native calls that the system can understand. Assembly programs written for the original TI-83 might not be compatible with the newer TI-83/84 Plus calculators because some calls that made sense in the TI-83’s architecture may no longer be valid in the TI-83/84+. A translation library (probably included in shells like MirageOS) ensures that calls for the TI-83 go to the new, updated places in the TI-83/84+ calculators.

Platform-independent code is written in a language that is interpreted by something that usually runs natively. For example, PHP is a programming language that is interpreted and executed by the installed PHP binary, which has already been compiled natively for Windows, Mac, and Unix-based operating systems. The PHP code that web scripters write are independent of the platform, allowing the code to work on multiple operating systems as long as PHP is installed for those operating systems.

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