FreeBSD
A free operating system based on the BSD 4.4-lite release from Computer Systems Research Group at the University of California at Berkeley.
FreeBSD requires an ISA, EISA, VESA, or PCI based computer with an Intel 80386SX to Pentium CPU (or compatible AMD or Cyrix CPU) with 4 megabytes of RAM and 60MB of disk space.
Some of FreeBSD's features are: preemptive multitasking with dynamic priority adjustment to ensure smooth and fair sharing of the computer between applications and users. Multiuser access - peripherals such as printers and tape drives can be shared between all users. Complete TCP/IP networking including SLIP, PPP, NFS and NIS. Memory protection, demand-paged virtual memory with a merged VM/buffer cache design. FreeBSD was designed as a 32 bit operating system. X Window System (X11R6) provides a graphical user interface. Binary compatibility with many programs built for SCO, BSDI, NetBSD, 386BSD, and Linux. Hundreds of ready-to-run applications in the FreeBSD ports collection. FreeBSD is source code compatible with most popular commercial Unix systems and thus most applications require few, if any, changes to compile. Shared libraries. A full compliment of C, C++, Fortran and Perl development tools and many other languages. Source code for the entire system is available. Extensive on-line documentation.
ftp://ftp.freebsd.org/pub/FreeBSD or try your nearest mirror site listed at the home site or buy the CD-ROM from Walnut Creek.