3Com Corp, Santa Clara has graduated to the ranks of blue chip companies – and there are still not too many of those in the high-tech sector. According to 3Com (these things are usually put out by the ratings agency rather than the client) Standard & Poor’s Corp has upgraded 3Com’s corporate credit rating to the lowest investment grade rung – triple-B-minus, up from double-B, but the outlook is positive, so it could graduate to a coveted rating in the low As fairly soon. 3Com’s convertible subordinated notes go up to doubleB+ from B+. The agency said the successful integration of acquisitions and continued product development could lead to higher future ratings, and that 3Com’s solid profitability and its existing product-line strength should provide some downside protection.