OS UPDATE

By Barry NanceSpecial to GCNDo Microsoft Corp.'s legal problems with the Justice Department portend a shake-up in the federal market dominated by the company's Windows operating system? Maybe. Maybe not. But managers have always had a choice of operating systems and, court findings notwithstanding, the reasons for picking one over another will remain largely the same.The key to choosing the right operating system is to first choose the right application or set of applications for the job. Decisions about operating systems, as well as the kinds of computers you buy, usually fall into place if you know what you're going to do with them.But it is not always that simple. If you are selecting from among equally capable applications, the biggest consideration becomes which OS to run those apps under. Or, if your organization has its own staff of programmers to build custom apps, choosing the right OS becomes more complex.This Buyers Guide identifies and characterizes operating systems for desktop PC, multiuser and server use.Operating systems almost always are specific to particular CPU architectures. The exception'fast becoming the rule in many cases'are operating systems for the Intel 80x86 CPU. The current incarnation of these CPUs can be found in the family of Pentium chips that power desktop machines and small servers.Alternatives to Microsoft Windows have always existed, but software manufacturers have focused most of their efforts on supporting Windows. Fewer applications exist for OS/2, MS-DOS, Santa Cruz Operation UnixWare and Linux, all of which run on systems built around Intel 80x86 CPUs.Linux also runs on several CPU platforms other than those of Intel Corp. Java applications, in theory, can run under any OS for which a vendor has licensed the Java run-time environment from Sun Microsystems Inc.Not only does Windows itself come in various flavors, Microsoft includes its own Java run-time environment in Windows. Microsoft markets its Windows 9x OSes for desktop PC users and its Windows NT Workstation for desktop machines with more memory and CPU speed.Windows 2000, Microsoft has said, will eventually replace Win9x and NT Workstation. And Windows 2000 Server will gradually supplant NT Server, which combines the operations of a file server and Web server in a single OS.For computers designed to do more than a typical desktop machine, there are sophisticated OSes designed for other CPU architectures.Hewlett-Packard Co. makes computers with Precision Architecture-RISC chips and that run HP's flavor of Unix, HP-UX. IBM Corp. builds RS/6000 computers, which contain PowerPC CPU chips and run IBM's AIX. Sun Microsystems has SunSoft Solaris, another Unix variation, for its Sparc chip computers. To complicate matters, Sun also has a version of Solaris that runs on 80x86 CPUs.Finally, there's MVS, which is specific to IBM 370 mainframes, and OS/400, which is specific to IBM AS/400 computers, as well as Apple Mac OS, which runs only on Macintosh computers.An OS with a graphical user interface makes working with files'copying, moving or deleting'easier, and it makes possible the development of apps that present the same GUI. Most of the operating systems in this guide are GUI-based.The Windows GUI is well-known; Unix and Linux rely on X-Windows; OS/2 incorporates an object-oriented GUI, and, of course, Macintosh computers have a graphical desktop metaphor.Some people consider the now-obsolete Windows 3.x a GUI for DOS. But generally speaking, MS-DOS, PC-DOS, MVS and OS/400 are command-line operating systems that require users to remember arcane commands, some which have a complex syntax. Similarly, error messages from these non-GUI operating systems are often cryptic.An OS that can run either multiple computer programs on behalf of several people or a single computer program that can accommodate multiple users concurrently is designated as multiuser. Unix and MVS are examples of multiuser operating systems. Such environments are advantageous if your application supports it and if spreading costs over many users makes economic sense.In contrast, a server OS is single-user for the person sitting at the server computer but can dole out files or Web pages to multiple networked users. For example, a computer running Windows NT Server can respond to requests from many networked users for files or Web pages, but those users must run individual copies of word processing, spreadsheet, accounting or other applications.A desktop OS is single-user and typically not used for serving files. Although Win98, NT and OS/2 Warp users theoretically can share files among users on a peer-to-peer basis, most organizations do not implement the peer networking features of these OSes. Making backup copies of files across multiple desktop computers is difficult, and a user interacting with a desktop machine that's also a server becomes disconcerted and frustrated when the machine appears to slow down because it's busy serving up files to other users.Unix systems generally are characterized as server-based because of the OS' multiuser design, but some agencies and departments forego its multiuser ability and use Unix in a single-user mode.Software makers generally set baseline retail prices, but such pricing might not reflect how your organization wants to use an OS. Be sure to check out each vendor's license fees and also take into account the hardware on which you run the OS.XXXSPLITXXX-