The new systems are the reason behind IBM's recent boasts that it is seeing strong growth in customer demand for its mainframes, which it expects to translate into improved financial results during the second half of 1998.

IBM said the performance lead of its computers should give it at least a year's jump overJapanese rivals Hitachi Ltd and Fujitsu Ltd with its US-based Amdahl unit. Both are manufacturers of IBM-compatible mainframes."The G5 Server's performance ends the debate and discussion about who offers the most mainframe-class performance," general manager of IBM's mainframe division David Carlucci said.

"Our customers expect and demand technology leadership from IBM -- and the G5 delivers in a big way," he said.

While over the years, IBM has remained the world's top supplier of mainframe computers, its technology has often lagged behind the performance offered by its competitors.

Hitachi's Skyline mainframe is considered the fastest single system now on the market, running at up to 900 million instructions per second.

IBM said the new Turbo model of its G5 mainframe line achieved the 1,040 MIPS performance rating using a single system composed of 10 processors. By contrast, Hitachi's Skyline is limited to eight processors in a single system. "This time IBM does have the edge," said David Floyer, anindustry analyst with International Data Corp. who was briefed by IBM ahead of the announcement. "This is the first time for a long time that IBM has recaptured the performance lead -- and I don't see that Hitachi will catch them."

Mainframe buyers put high value on top performance, Floyer said, because it provides the machines with a competitive edge in handling customer requests. This in turn, should give IBM an edge as companies look to replace older mainframe systems. The new G5 line replaces IBM's G4 series, with top speeds of 440 MIPS, which was introduced in the spring of 1997. The performance improvements of the G5 allows IBM to honour its commitment to customers to at least double the performance of its mainframe in every product upgrade cycle, Carlucci said.

IBM already holds the lead in so-called multi processor systems that cluster together multiple mainframes to share even larger data processing loads, but single system measurements are important because many customers prefer such systems.IBM's cluster technology can harness the power of up to 32 mainframes to deliver performance of almost 30,000 MIPS.

The standard version of the G5 is set to begin shipping in mid-August, with the "Turbo" version due in mid-September, the company said.

Floyer said IBM may hold on to its technology advantage for several years as rivals face difficult choices about whether to continue to build products using a mix of older bipolar chips and newer CMOS technology or license IBM's own technology. IBM's mainframes are entirely based on CMOS chips, which can be manufactured at lower cost and are easier to work with, giving IBM decided economic advantages over mainframe rivals, Floyer said.

As a result, IBM is beginning to set its sights on makers of increasingly powerful "open- systems" computers such as Hewlett-Packard Co. and Sun Microsystems Inc. IBM will have to ensure that the power of its mainframe chip technology continues to multiply each year, while also being prepared to cut the costs of software andservices in order to remain competitive against these lower cost rivals.