The design is made possible by Unisys' so-called SCAMP semiconductor chip, which houses more than 10 million transistors.
The top model has a maximum disk storage capacity of 1.4 gigabytes, or 1.4 billion characters.
"This gives Unisys the opportunity to develop a new, very attractively priced family that is architecturally compatible with Unisys' line, but
physically more attractive because of its desktop size," said Ulric Weil of Weil & Associates, a Washington computer consulting firm.
The micro mainframe, which Unisys is calling Micro A, can support the work of up to 16 users at desktop terminals.
The price is substantially less than the $100,000 starting cost of the Unisys A series and most of its competitors.
The entry-level price of the Micro A would be $25,000, which would buy the base unit, a monochrome monitor, a keyboard and the operating system. With seven terminals, the total price would be about $60,000 and include some peripheral equipment, such as a 280-megabyte disk drive. A system with 16 terminals would cost about $80,400.
Heretofore, a mainframe was a bulky, stand-alone, upright machine about the
size of a huge furniture cabinet. Large mainframes are generally housed in their own air-conditioned rooms.
Weil said the Micro A design would, for example, allow a small group of designers to share a mainframe computer that in turn could be linked with that of another group down the hall.
Sanjiv Hingorani, an analyst at Salomon Brothers, the New York brokerage firm, said the Micro A was "evolutionary, not revolutionary," terming the line "a downward extension" of the Unisys A series.
Hingorani said the Micro A probably will not have a significant impact on Unisys' revenues since it may supplant the lower-end Unisys models and is relatively low-priced.
Unisys declined to speculate on system sales.
Company spokesman Steven Lubetkin said Unisys expected 60 percent of the Micro A line to be sold to present Unisys customers, many of whom will supplement their Series A computers with the new Micro A line.
Weil said Unisys has wisely set up the system so as not to supplant its other models immediately. Over the long term, however, he expected the Micro A line to replace existing equipment.
The system is particularly attractive for businesses or their units with 16 or fewer users and "reasonable requirements for input and output," Weil said. "It's not the answer to anybody's dream."
Unisys said the lower price would significantly beat the price of the IBM's AS400 mainframe, which is a major competitor. It's also competitively priced against Digital Equipment Co.'s new line, although that is more geared for the scientific and technical market.