The AS/400 is known for its closed architecture. Does it have a future in an open systems world? It seems like the computer trade press is giving a lot of attention to open systems lately. Should AS/400 users regard it as media hoopla or a real phenomenon?

A recent International Data Corporation (IDC) white paper explains, "Since 1946, the International Standards Organization (ISO) has been involved in worldwide standards development and adoption on behalf of its almost 100 represented countries. In 1977, the ISO decided to expand its standards- setting work to include computer-to-computer communications. At that time, a formal working group was given the charter to develop the OSI Reference Model."

OSI means Open Systems Interconnect, and IDC forecasts that it will be, "the next big step in the evolution of networking computers to computers, applications to applications and, most importantly, end users to information."

The U.S. government now mandates that its computer acquisitions meet OSI standards. And it's no surprise that IBM announced, with OS/400 version 2, its OSI Communications Subsystem/400, OSI Message Services/400 and OSI File Services/400. IBM sells computers to the government, and without OSI support, the AS/400 would never get in the door.

But open systems can have different meanings, depending on whom you talk to. The IEEE says, "an open systems environment supports a comprehensive and consistent set of informational technology standards and functional standards to accomplish interoperability and portability of applications, data and people." So the IEEE thinks that an open system is one based on standards. But in a recent Computerworld editorial, Scott McNealy said, "Many vendors equate open systems with standards. However, these are not the same thing." And on the same page, Bill Gates of Microsoft said that open systems simply means, "Customers are able to choose their products and solutions from a host of hardware and software vendors . . . the personal computer industry shows how this can be accomplished with great benefits to the user."

Personally, I like Bill Gates' definition best. The PC marketplace swarms with vendors, and customers have a multitude of product choices at very reasonable prices. Unfortunately, that's the very reason why IBM planners are ambivalent when it comes to AS/400 openness. They want to expand their market, but they don't want to lose control over it.

Wanting to have it both ways, IBM is using its propaganda machine to convince users that the AS/400 will be open, proudly touting the application programming interfaces (APIs) provided first in OS/400 version 1, release 3, and now in OS/400 version 2, release 1. Although these APIs will provide end users with at least a limited degree of access to OS/400 internals, some vendors have found them to be unacceptably slow, and cannot use them for developing performance-intensive system tools and utilities.

While turning its openness smiley face towards users, IBM is choking independent software vendors that need internal interfaces to build compilers, productivity aids and other system utilities. Level 40 security blocks access to any OS/400 interface that IBM designates as off limits. If a needed function is not available through an API, vendors are supposed to ask IBM to create a new API. And while the vendors' product plans are on hold, IBM gets to preview them by examining the API requirements. In today's fast-paced market, that may mean death for software vendors caught between IBM and a market that doesn't want to wait.

IBM planners may imagine their strategy will create an AS/400 world with little competition from independent software vendors -- a world where customers sing the IBM openness song. But reality will quickly set in when Hewlett Packard, NCR, DEC, Bull and other vendors penetrate the market with their own open systems, stealing market share from IBM. The propaganda will burn away like morning fog.

If the IBM planners could overcome their lingering fear of the plug compatible manufacturers from the System/370 days, they could lead the open systems parade with an AS/400 that is truly open. Hidden beneath OS/400 is an architecture that computer scientists would call a virtual machine. IBM simply calls it machine interface, or MI. It's the result of the 1970's Future Systems project into which IBM poured untold millions to develop a successor to the System/370 mainframe line. That project was scrapped, but the architecture survived, first in the System/38, and now in the AS/400.

Some developers who use MI wonder why IBM doesn't publicize it and open it up to the world. It could be the most significant advance in computer architecture since the System/360. It has the performance characteristics of assembly language, but eliminates much of the pain involved in low-level programming. Its powerful, simple elegance is ideal for building compilers, system utilities and high performance application software. If IBM wants to lead the market with a standards-based, open system, MI would be the ideal platform on which to build it.

But IBM planners may be afraid that opening MI would allow hardware competitors to clone the AS/400, the same way the plug compatible manufacturers cloned the System/370. However, the MI specification could not be cloned directly -- the way the System/370 instruction set was. The hidden function embedded in the layers of microcode is orders of magnitude more complex than the function driving the System/370 instruction set. Cloning it would be prohibitively expensive, even for a vendor with deep pockets. And after 12 years in production and enhancements too numerous to list, who could ever catch up now?

Others within IBM may want to keep independent software vendors away from MI and the system internals just to avoid headaches. IBM doesn't like to be annoyed by a bunch of software vendors asking for internals documentation, pointing out all the ugly little design and coding flaws they find in the operating system. But I think IBM would better serve its own interests by cooperating with the nerdy vendors. Some have the expertise to teach IBM developers things they don't even know about their own products.

Hidden within OS/400 is a developer's paradise of untapped function. If IBM wants to sell more AS/400s, they should publish parameter lists, function descriptions and other vital interface specifications for the OS/400 system modules, and encourage vendors to use them. Like the PC market, the midrange market would swarm with vendors, customers would have choices and IBM would sell more AS/400s.

Security level 40 can be maintained, even with vendor openness. There are only a handful of system modules that comprise the security kernel. They can remain off limits, and the rest (around 3,000!) can be opened to vendors who want them.

Wake up and smell the coffee, IBM. It's going to be an open systems day.