IBM Corp rolls out a fourth generation of its System 390 CMOS mainframes today. It’ll be claiming G4 – not to be confused with the future generation of PowerPC chips with the same moniker – are the fastest cheapest of their kind yet. The third generation of CMOS – complementary metal oxide semiconductor – processors launched last October delivered almost double the performance of the second generation. However the fourth generation is expected to bring only up to a 30% improvement. Indeed the new CMOS uniprocessor is expected to deliver about 65 MIPS rather than the 80 MIPS IBM needs and some had hoped for. The embarrassing explanation for this seems that if IBM winds up the clock on its new CMOS microprocessor so that it will deliver 80 MIPS, the thing runs so hot it needs water cooling, when the reason for going from ECL to CMOS was to pension off the plumbers (CI No 3,134). There were 13 models in the G3 line, expect a similar number of G4s today. There’s supposed to be some network computer angle to the announcement, though the IBM NC people we spoke to said that while the Network Station Manager for S/390 software is due by the end of this month, it’s not part of Monday’s announcement. The RS/6000 Network Station Manager will be out end by the beginning of next quarter.
