A lot of the IT people I know are loath to simply throw away a computer as long as it works. Of course, that means that these people either have a heap of equipment in closets or they have found creative ways to make them useful. With a plethora of lightweight operating systems available, you can easily build a system for a number of purposes: a small Web server, a small FTP server, or equipment to learn the ins and outs of how operating systems work.
While Linux is often considered the alternative operating system of choice, there are many useful and interesting and truly alternative operating systems out there that might be able to help you solve a problem using that old system without breaking the budget. There's even an open source version of DOS called FreeDOS available, which can be extremely useful in certain situations. But these alternatives may not work on your ancient 286 or 386 computers. Don't throw those antiques out yet. You've still got options.
MINIX is a free clone of UNIX with all of the source code readily available. Be careful not to confuse it with Linux, however. While freely available, MINIX is not distributed under the GPL (as Linux is) and is not targeted at the same user. Whereas Linux is also UNIX-like and is being used for major mission-critical applications and is growing every day to fit into this role even better, MINIX does not contain high-end features like Linux and UNIX.
MINIX was written from the ground up without any AT&T UNIX code. As such, the developer is able to distribute it in any way they see fit. According to the MINIX Web site, while MINIX is considered copyrighted software, it can be freely distributed in any form and can be treated as if it were in the public domain.
While it lacks the full feature set of its cousin, MINIX does contain enough features to be both useful and educational. For example, this MINIX site runs on version 2.0.2 of MINIX and includes FTP capabilities in addition to the obvious Web server.
There are two current versions of MINIX—versions 1.5 and 2.0—and each is targeted at different hardware platforms. Version 1.5 runs on Intel 8088 processors and up, Macintosh, Amiga, Atari, and SPARC hardware, while version 2.0.3 currently only supports Intel processors from 8088 and up.
The minimum system MINIX can be reasonably installed on is an IBM PC/AT or PS/2 with a 286 processor, 2-MB memory, a 720-Kb disk drive, and at least 35 MB of free space on an AT, ESDI, or SCSI hard disk with an Adaptec 1540 SCSI controller. IDE drives are also now supported under MINIX.
MINIX 2.0 can also run on XTs with only 640 KB of RAM. However, version 2.0.3 of the product is unable to do so, although the next release will address this problem.
Different installation files are required for MINIX, depending on the machine onto which you intend to install it. For example, one set of distribution files is intended for 386, 486, and Pentium machines (the "regular" file set), another set for 286 machines under certain memory and hardware configurations (the "small" file set), a third set for 8086 and 286 machines with a single 720-KB drive (the "tiny" file set), and a fourth set for machines with an 8086 or 286 processor and a single 360-KB drive (different "tiny" file set). All of these sets of files can be downloaded from the MINIX 2.0.3 download site.
ELKS—the embeddable Linux kernel subset
As its name implies, ELKS is an operating system containing features that are a subset of Linux. The initial development for this project is targeting the 8086/8088 processor series with eventual development for the 286's protected mode. While still in beta, ELKS has come far enough along to allow an ELKS system to boot, provide TTY consoles, mount MINIX file systems, provide serial and parallel data transfer, use SLIP for inter-machine connections, and provide swapping ability.
ELKS is intended for very low-end machines and embedded systems such as palmtops. The ELKS Web site mentions the lack of availability for higher end machines in third world countries as part of the reason for this development. This is a laudable goal and can play an important role in the development of these areas.
Getting and using ELKS
Unlike Linux and MINIX, ELKS is not a ready-to-run operating system. To use it, you first need to get a full Linux system up and running so that you can compile the ELKS kernel. The ELKS source and installation instructions can be downloaded from the official ELKS Web site.
The first true Linux machine that I have discussed, muLinux, is a minimalist version of Linux. Unlike MINIX and ELKS, muLinux is not under any active development but does provide a playground where one might learn more about Linux. However, it's not based on current Linux standards. In fact, it is based on the 2.0 version of the Linux kernel. Right now, version 2.6 of the kernel is under active development.
Though it may not be very useful for a production system, muLinux does offer you a place to poke around a simple Linux installation with full source code to learn more. Even though it's based on an older kernel, it's still good enough to glean some useful information from.
Other small distributions
There is no end to the number of small Linux distributions that are available. While they aren't as full featured as the big players like RedHat and SuSe, not every task requires a sledgehammer to get a job done.
It's also important to mention BSD in this context. While often overlooked in favor of Linux, BSD is extremely full featured and seemingly safe from the current legal drama overshadowing Linux. A partial list of these Linux and BSD distributions can be found here.
Whether you want to learn more about how operating systems are built and work or you need to resurrect that 286 to run as a small FTP server, there is an alternative operating system out there that will work for you. No longer viewed as an alternative in many cases, a full Linux distribution may fit the bill but may also provide too much.