But Computer Associates, because it charges its mainframe customers according to how powerful their hardware is, has been able to increase its software revenues.

It expects the number of mainframe customers to decrease by 44% - they'll be interested in value added software to their current mainframe solutions.

Many mainframe customers run two machines: one in their primary data center, and one in their backup data center-fully active, partially active, or on standby-in case there is a catastrophe affecting the first building.

Mr. Platt said the new machines were aimed primarily at traditional mainframe customers who are considering "downsizing," industry jargon for moving applications to smaller, more cost-effective computers.

In a recent conference call with the International Business Machines Corporation, a securities analyst asked if the company ever again expected to win a new mainframe customer.

Brocade added mainframe customers with FICON and FICON CUP support on the SilkWorm 12000.

It is not too soon for mainframe customers to start thinking about the new course on which IBM will soon embark.

The Multiprise 3000 is popular among smaller mainframe customers, particularly those running the 31-bit z/VSE V3R1 operating system.

NCR can do this more rapidly than I.B.M. or Digital because it never acquired the large installed base of mainframe customers those companies have.

With parallelism in vogue, I.B.M. is worried that its mainframe customers might rush to install parallel Fortran, only to discover their overall system has actually become slower.