Integrated Silicon Solution Inc, a Sunnyvale designer and marketer of static RAMs and other non-volatile memory chips, has filed to go public with an initial offer of 3m shares, 1.5m of them new. No target price or plans for the cash were given.The underwriting is being jointly managed by Donaldson, Lufkin & Jenrette Securities Corp, Alex Brown & Sons Inc and Soundview Financial Group Inc.

US Robotics Corp, Skokie, Illinois modem maker plans next week to file to offer 2.25m shares, 1.25m of them new, to raise more working capital.

Rational Software Corp, Santa Clara, California software development tools specialist, has filed to offer 3.75m new shares – equivalent to 11.25m since it plans a one-for-three consolidation ahead of the offering – with 2.2m of the shares on offer being new. The offer will raise an indicated $26.8m for the company before expenses, to be used for working capital. Hambrecht & Quist LLC, Alex Brown & Sons Inc and Wessels, Arnold & Henderson LLC underwrite.

Portugal Telecom SA has filed with the US Securities & Exchange Commission for an initial public offering of 7.1m American Depositary Shares, each representing one ordinary share as part of its worldwide offering of 23m ordinary shares and Depositary Shares by the company and its parent Communicacoes Nacionais SGPS SA, a holding company formed by the Portugese government. The state will see its stake in Portugal Telecom, the principal telecommuncations provider in Portugal, fall to about 73.7% after the offerings. The state holding company will receive the proceeds from 29.43m shares it plans to offer and does not intend to invest any of the proceeds in Portugal Telecom.Merrill Lynch & Co, S G Warburg Securities Ltd, UBS Lts and Banco ESSI SA are the global co-ordinators.