General AIX information:

Types of unis ox

Solaris – Sun Microsystems’ implementation, of which there are different kinds available: these are Solaris OS for SPARC platforms, Solaris OS for x86 platforms, and Trusted Solaris for both SPARC & x86 platforms; the latest version is Solaris 10 OS
AIX – short for Advanced Interactive eXecutive; IBM’s implementation, the latest release of which, is the AIX 5L version 5.2.
SCO UnixWare and OpenServer – are implementations derived from the original AT&T Unix® source code acquired by the Santa Cruz Operation Inc. from Novell, and later on bought by Caldera Systems; the latest versions are UnixWare 7.1.3 and OpenServer 5.0.7
BSD/OS – the Berkeley Software Distribution (BSD) Unix implementation from Wind River; its latest version is the BSD/OS 5.1 Internet Server Edition

IRIX – the proprietary version of Unix from Silicon Graphics Inc.; the latest release of which is IRIX 6.5
HP-UX – short for Hewlett-Packard UniX; the latest version is the HP-UX 11i
Tru64 UNIX – the Unix operating environment for HP AlphaServer systems; Tru64 UNIX v5.1B-1 is the latest version
Mac OS – Mac operating system from Apple Computer Inc. having a Unix core; the latest version is the Mac OS X Panther
Flavors that are available for free, include:
FreeBSD – derived from BSD, it is an advanced OS for x86 compatible AMD64, Alpha, IA-64, PC-98 and UltraSPARC® architectures; the latest versions are FreeBSD 5.2.1 (New Technology Release) and the FreeBSD 4.9 (Production Release)
NetBSD – Unix-like OS derived from BSD and developed by The NetBSD Project; it is shipped under a BSD license and the latest release is NetBSD 1.6.2
OpenBSD – multi-platform 4.4BSD-based Unix-like OS from The OpenBSD project; its latest release is OpenBSD 3.4
Linux -- a Unix-type OS originally created by Linus Torvalds, the source code of which is available freely and open for development under GNU General Public License; there are numerous Linux distributions available

IBM-AIX