SAN FRANCISCO – Google Inc. showed off its nearly completed mobile software system to about 3,000 computer programmers Wednesday, hoping to cultivate more services and advertising for people on the go.

Although brief, the demonstration at the Internet search leader’s annual developer conference in San Francisco represented the most extensive public look so far at “Android” – an open-source platform being designed for “smart” phones and other mobile devices that surf the Web. Android was first announced nearly seven months ago.

The bells and whistles unveiled Wednesday included: a way to unlock phones by drawing a specific shape on the touchscreen instead of entering a password; bookmarks for favorite Web sites on the device’s home page; a “compass” tool that automatically roams with the phone while a user looks at photographic images of a city map; a magnifying tool to zoom in on Web content; and a mobile version of the video game “Pac Man.”

The demonstration relied on touchscreen technology similar to Apple Inc.’s iPhone, but Android can also be tailored to work with a tracking ball, said Andy Rubin, who is overseeing the project.

While acknowledging the work on Android is nearly done, Rubin deflected a question about how much longer consumers will have to wait for a phone powered by the new software. Sticking to the timetable Google has used throughout the project, Rubin said Android will hit the market some time during the final six months of this year.

Several handset makers, including Samsung Electronics Co., HTC and LG Electronics Inc., are among the 34 partners that Google has recruited to help launch Android.