[转帖]: 一个Linux爱好者眼中的FreeDOS

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一个Linux爱好者眼中的FreeDOS（翻译版本）

原作者：Russell C. Pavlicek      pavlicek@linuxadvocacy.net
翻译者：Joey Andrise（joey）   openguet@yahoo.com.cn

正如那些构思了开放源码的人那样，我花了很多时间去考虑开放源码在企业界的未来。我并没有花多少时间去思考开放源码如何能够改进那些过时的技术。但是，就是有一些人正在这样做。

考虑一下 MS－DOS 吧。如果你和我一样大（大到得花时间思考才知道自己究竟有多大），你一定记得 MS－DOS。并且如果你回想得够久够努力，你应该会想到一些关于这个“诡计”已经模糊了的回忆：需要手动去管理内存，载入光驱驱动，还有配置显卡以便正确显示。

DOS，它最好应该呆在那些被时间所埋葬的杂物堆里。大概我也曾这么想吧。

不管你相不相信，有一群开放源码的开发人员正忙于构建一个更好的DOS系统。为什么？因为DOS是一个存在了很久的平台，对于一些嵌入式应用程序来说，它仍然用的到。一个嵌入式应用程序需要一个既可靠又廉价的系统作为基础。有鉴于 MS－DOS 这个产品对微软已经不再重要而同时其对于嵌入式开发人员又关系重大，一些人相信构建一个同 MS－DOS 兼容的开放源码操作系统是必要的。

FreeDOS 项目开始于1994年，为的是抵消微软试图废掉 MS－DOS 并把大家都赶上 Windows 的行为所造成的影响。它不包含任何来自微软方面的代码，它被设计成在同 MS－DOS 相类似的方式下工作。FreeDOS 并不保证它能够以与 MS－DOS 一样的方式完成所有的任务，不过它正努力去实现这个目标。FreeDOS 的规范说明均是来自于描述 MS－DOS 的公开发行文档之中。FreeDOS 仍处于测试阶段，不过系统本身已经是可以使用的了。现在，FreeDOS 正处于第七个版本的开放测试中，绰号叫做“长矛”（SPEARS）。

我使一台在我家地下室的古董机子－－486/DX4 120MHz ,12MB 内存－－恢复了青春并继续投入使用。我的机子装备的是 270MB 的硬盘，而它在安装了整个操作系统及其源代码后仍有足够的富余空间（最近那次一个 270MB 硬盘对任何东西都足够大是什么时候的事了？）。事实上，系统在完全安装后只会占用 35MB 的硬盘空间。

FreeDOS 的安装是足够简单的了，我只试了一次就使我的老机子开始工作了。我从 Freedos.org 的下载页面上下载了它的 iso 文件，然后我刻录了光盘，制作了引导软盘。这张 FreeDOS 光盘已经包含了一个光盘驱动，但是我的4倍速的IDE光驱实在是太老了，没有被认出来，于是我只好找出那个被我丢在一旁很老的原厂驱动来解决问题。系统安装的时候要求你得呆在旁边，因为它会一直要求你确认安装不同的组件。这还不算是一个很大的负担，因为安装只会花费几分钟的时间。

启动系统看起来和 MS－DOS 不大一样。首先，这里有一个灵巧的引导管理器，它允许你引导多个操作系统，这对于开发环境是很有帮助的。其次，引导信息有很大的不同，考虑到各种各样的驱动都要在载入时识别自己，这也就不奇怪了。

等到系统启动完毕，你可能会发现很多东西还是那么地熟悉，同时另一些玩意则变得精简了些。“dir” 命令的输出看起来就和我记忆中 MS－DOS 中的一样，“edit”命令看起来还是和 MS－DOS 里面的“edit”一样怪异。大部分的标准 DOS 命令在 FreeDOS 下看起来没什么变化。有一些命令（比如说“men”）使用了更精简的选项开关。谢天谢地，这个“/?”选项看来可以获得大部分命令的选项列表；同样，有一个相当好的“help”命令，用它可以获得许多命令的相关说明。

同时有许多因素表明这还是一个发展中的系统。安装文档里面警告软盘的存储速度较慢－－确实是这样，不过还好，它工作还算正常。“scandisk”看来只能完成第一个分区的扫描任务。而“format”命令则似乎只能做快速格式化，不论你键入的是什么选项。

同样地，FreeDOS 也提供了许多可供选择的软件包。当 Linux/Unix/BSD 的老鸟们看到竟然有许多版本的 vi 和 Emacs 可供选用的时候一定会激动不已。同样还有许多的编程语言像 Bywater Basic（我在一些早期的Linux发行版里面见过以后，就再没接触过了），还有一个汇编程序。

也许最有趣的附加包就是 Seal 了。Seal 是一个类似于 Windows 的 GUI 界面，如果你感兴趣的话。我安装的这个版本只包含了一些应用程序，但它展现了巨大的潜力。

在检查了所有的软件包以后，下一步该干什么就很明显了：载入一些“严谨的”基于 DOS 的软件，看看会发生什么。我的选择（也许是受了绰号“长矛”的影响吧 ）是“命运之矛”（“Spear of Destiny”），Wolfenstein 3D 的资料片。Freedos.org 网站为此还做过一些研究，为的是找出如何释放出刚好够这个游戏运行的内存的方法（有个地方的体系要做一些改变－－与 MS－DOS 相比较），不过我一将内存搞定，游戏就运行得很好了。这台486的老爷机运行得还很欢快呢（上次我说486机子运行得“欢快”是什么时候？），而游戏也一如既往地跑着。

不过，源于真正的开放源码精神，Freedos 并不满足于成为一个现有技术的模仿者。除了像 Seal 这样给人印象深刻的附加包以外，要说更早的，还有正在进行的建立纯32位内核的努力。是的，在弗吉尼亚州，那里有一个 DOS 救世主。也许在某天，FreeDOS 会成为一个不需要无休止地去管理内存的 DOS 系统。在技术的推动下，人们尝试着去改进系统直到没有人再说一个“不”字，这难道不是一件很好的事吗？？

我确实希望 FreeDOS 项目能旺盛地发展下去。开放源码讨论着自由使用，但它同时也意味着自由选择。而 FreeDOS 给了人们另一个选择。如果你不想要 DOS 的话，试试其他的吧。但如果 DOS 是你所构建的特殊设备之关键所在，请尝试一下 FreeDOS 吧，它值得你一试。

A Linux guy looks at FreeDOS

Friday February 15, 2002 - [ 05:03 PM GMT ]   
Topic - Other OSes

- By Russell C. Pavlicek -
As someone who writes about Open Source, I spend quite a bit of time considering its future in the enterprise. I don't spend much time reflecting on how Open Source can improve on the technology of yesteryear. But there are people who do just that.

Consider MS-DOS. If you are my age (old enough that it takes too long to calculate how old you really are), you remember MS-DOS. And if you think about it too long and hard, you might begin to get the shakes remembering the machinations required to manage memory, load CDROM drivers, and get the graphics to display correctly.

DOS. It's one of those things that is best left buried in the crevices of time. Or so I thought.

Believe it or not, there are Open Source developers busily building a better DOS. Why? Because DOS is a long standing platform that is still used for some embedded applications. And embedded applications need a reliable, inexpensive base. With MS-DOS no longer an important product for Microsoft and its cost relatively significant to embedded developers, some folks believed there was a need for an Open Source DOS- compatible operating system.

FreeDOS was a project started in 1994 to counteract Microsoft's stated intentions to do away with MS-DOS and move everyone to Windows. It employs no Microsoft code and is designed to be a work-alike equivalent to MS-DOS. FreeDOS does not guarantee that it does everything the same way MS-DOS does, but it attempts to get it all done nonetheless. The specification for FreeDOS is derived from public documentation describing MS-DOS. It is still in beta test, but the system is quite usable. Currently, FreeDOS is at version Ripcord Beta 7, aka "SPEARS."

I resurrected an old 120 MHz 486/DX4 12MB machine in my basement and proceeded to get to work. Because my machine is equipped with a 270 MB disk drive, it has more than enough space to install the entire operating system and its source code (when was the last time a 270 MB disk was more than enough space for anything?). In fact, the total installation took only about 35 MB of disk space.

The installation of FreeDOS was simple enough, once I got my old hardware running. I downloaded the ISO image from Freedos.org's download page, burned the CD, and cut the boot floppy. The FreeDOS CD does include a CD driver, but my 4x IDE CDROM was so old that it wasn't recognized. So I had to use an old vendor-supplied CDROM driver I had lying around. The installation requires that you stay around during the process, because it constantly asks for verification about installing various elements of the system. It is not a large burden, though, because installation only takes a few minutes.

Booting up the system looks different than MS-DOS. First, there's a neat little boot manager that allows you to boot multiple operating systems. This is very useful in a development situation. Next, the boot-up messages are very different. This is not surprising, considering the various drivers identify themselves as they load.

Once the system is booted, you are likely to notice that some things are familiar, while others have changed slightly. The output of the "dir" command looks just like I remember from MS-DOS. The "edit" command looks spookily like the MS-DOS "edit" command. Most of the normal DOS commands look about the same under FreeDOS. Some commands (like "mem") use slightly different switches. Thankfully, the "/?" switch seems to work to get a list of switches for most commands. There is also a decent "help" command that documents a number of commands.

There are several factors indicating that this is a work in progress. The installation notes warn that the floppy access is slow -- and it is. It does work fine, however. The "scandisk" utility only seems to complete the first stage of work. The "format" command only seems to do a quick format, regardless of which switches you specify.

There are a number of optional packages as well. Veterans of the Linux/Unix/BSD crowd will be thrilled to learn that versions of "vi" and "emacs" are available. There are also languages like Bywater Basic (which I hadn't touched since finding it on some of the early Linux distributions) and an assembler.

Perhaps the most interesting add-on is Seal. Seal is a GUI that gives you a Windows-y interface, if you want one. The version I installed only contains a few applications, but it shows a good deal of potential.

After checking out the software, the next step was obvious: load up some serious DOS-based software and see what happens. My choice (perhaps suggested by the code name "SPEARS") was "Spear of Destiny," the relatively unsung sequel to the classic "Wolfenstein 3D". It took some research on the freedos.org Web site to find out how to free up enough low memory to run the game (this is one area where there are some syntax changes compared to MS-DOS), but once I got the memory in shape, the game played just fine. The 486 was quite chipper (when was the last time I called a 486 "chipper?") and the game played true to form.

But, in the true spirit of Open Source, FreeDOS is not content to be an imitation of the existing technology. In addition to impressive additions like Seal, mentioned earlier, there is an effort underway to create a true 32-bit kernel. Yes, Virginia, there is a DOS Santa Claus. FreeDOS32 might someday be a DOS that doesn't require endless gyrations to manage memory. Isn't it great what motivated technical people can try to do when there is no one in the way to say "no?"

So, while I certainly hope that DOS does not experience a resurgence as a general-purpose business desktop, I do hope that the FreeDOS project thrives. Open Source talks about freedom to use, but it also means freedom to choose. FreeDOS gives people another choice. If you don't want DOS, try something else. But if DOS might be the key for that special device you are building, check out FreeDOS. It is definitely worth a look.

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