An unconfirmed report was circulating yesterday that Hitachi Ltd had signed to buy a 49% stake in the US operations of the National Advanced Systems IBMulator subsidiary of National Semiconductor Corp, with an unidentified partner – not NatSemi, taking the other 51%. The same source said that in Europe, Comparex Computer Systeme GmbH, which markets Hitachi mainframes in competition with National Advanced, is expected to take 100% of NAS Europe. If the report stands up, the only major questions are the identity of the US partner and the prices being paid. Although Memorex Telex International NV might be the most appropriate US partner for Hitachi, it doesn’t seem likely because the company would find it hard to raise the cash for a 51% stake – the partner is therefore more likely to be a financial than a manufacturing company. Possibilities include a leasing company or the financial subsidiary of one of the Baby Bells, with Bell Atlantic Corp or BellSouth Corp the ones that have shown most interest in related areas. The US partner has likely been chosen simply as a figleaf for Hitachi on the grounds that US users are still thought to be chary of buying their mainframes from an overtly Japanese company. National Semiconductor in Santa Clara had no comment on the report that a deal was near completion.