CAMBRIDGE, Mass. - A project that hopes to supply developing-world schoolchildren with computers for less than $200 has extended a promotion in which a customer buying the machine in the United States or Canada automatically donates a second one to a poor country.

The One Laptop Per Child Program said the "Give One, Get One" program will now run through Dec. 31, instead of ending Nov. 26.

The non-profit spinoff from the Massachusetts Institute of Technology said customers in the United States and Canada will pay $399 for two children's laptops, with the buyer taking one of the green-and-white, low-power "XO" machine. The other is sent to a child in a country such as Rwanda, Afghanistan, Cambodia, Haiti or Mongolia.

"In the past 10 days, we've experienced an outpouring of support from the public that is truly gratifying and encouraging," said Nicholas Negroponte, the program's founder.

"Because so many people have asked for more time to participate, either individually or in order to organize local and national groups to which they belong, we have decided to extend Give One Get One through the end of this year."

The computers were dreamed up as $100 laptops but cost $188.

The laptop has a homegrown user interface designed for children, boasts built-in wireless networking, uses very little power and can be recharged by hand with a pulley or a crank. Its display has separate indoor and outdoor settings so it can be read in full sunlight, something even expensive laptops lack.

Mass production was delayed until early this month because of reluctance from some potential buyers.