Motorola Inc has unveiled a credit card-sized wireless receiver for use with palm-top computers and personal communicators. The NewsCard incorporates a one-way modem and 128Kb memory. It can receive and store information such as electronic mail, share quotes, news updates and data files automatically as they are broadcast. The user transfers the data by inserting the card into the PCMCIA slot on the hand-held computer or communicator. NewsCard is a smaller version of NewsStream, a pager-like unit that picks up and stores data for transfer to desktop and laptop computers. NewsCard will ship next quarter, at $340 in volume.