The dollar rose against the yen but fell against the euro in Asian trading Friday morning, as investors mostly stayed on the sidelines ahead of a speech by U.S. Federal Reserve Chairman Alan Greenspan. The dollar bought 110.34 yen on the Tokyo foreign exchange market at 11 a.m. Friday, up 0.40 yen from late Thursday and above the 110.07 yen it bought later that day in New York. The euro rose to $1.2296 from $1.2290 from late Thursday. In New York late Thursday, the pound rose to $1.8010 from $1.7998. The dollar fell to 1.2571 Swiss francs from 1.2645, and was unchanged against the Canadian dollar at 1.1914. On Thursday in New York, where trading was extremely thin, the dollar was modestly lower versus the yen and the euro, which rose to its strongest level in more than a week. Analysts said investors were staying on the sidelines ahead of Greenspan's speech Friday. The Fed chairman's speech, entitled "Reflections on Central Banking," is expected to be a legacy-oriented address unlikely to include any market-moving comments. But the possibility that Greenspan might comment on monetary policy or the impact of high oil prices on the U.S. economy was an extra incentive for investors to exercise caution in what has been an illiquid market. Traders said the yen may also face downward pressure on a warning from France's top terrorist investigator in a published interview Thursday that al-Qaida could be preparing to attack a major financial center in Asia -- such as Tokyo or Singapore -- to undermine investor confidence. The euro had risen further against the dollar before the publication Thursday of an index of business confidence in Germany, Europe's largest economy, which unexpectedly fell in August after rising for two consecutive months. Stronger economic growth can boost a currency by attracting international investment and indicating strong demand for its exports.