IBM's top rivals in personal computers have called a news conference for next Tuesday at which they are expected to announce an alternative design for the way information flows inside a personal computer.

The new design would make it possible for the companies to build personal computers that rival IBM's 18-month-old Personal System-2 line without departing so far from the older standard, analysts said.Compaq Computer Corp. of Houston is leading the challenge, which may eventually include as many as 30 companies that make personal computers or related products, said Jim Weil, an analyst for Gartner Securities Corp.

Calling next Tuesday's news conference in New York are Compaq, Japanese-owned Epson America and NEC Corp., Hewlett-Packard Co., NEC Corp., Italy's Ing. C. Olivetti, Tandy Corp., Wyse Technology and Zenith Data Systems.

The joint project could put additional competitive pressure on IBM, but it might also help IBM by serving as an acknowledgement that its new Personal System-2 line has features that are worth duplicating, Weil said.

IBM could benefit if the delay in bringing the new computers to market gives IBM a chance to get its line better established, said George Colony, president of Forrester Research Inc. in Cambridge, Mass.

Colony said he thought creating a new standard was a bad idea because, "There would be further confusion on the part of the users, and that would translate into slower sales."

The new standard is for a "bus," which controls the way information flows through a computer. The more advanced models of IBM's Personal System-2 line use a new bus called Micro Channel. IBM's rivals use the older bus that was used in IBM's PC AT.

Weil said IBM's rivals will claim that their new bus offers all the power of IBM's Micro Channel but allows people to continue using their older add-on equipment, such as circuit cards. IBM's Micro Channel requires users to buy all new add-on equipment.