NCR Corp yesterday complemented its first notebook computer, the 3120, with the long-promised stylus-driven 3125, which is built around the 80386, weighs 3 lbs 14 oz and 1.2 thick. In contrast to the machines announced so far, the NCR box has been designed to run any of the pen-based operating systems – Go Corp’s PenPoint and Microsoft Corp’s Pen Windows are the leading contenders. The company is also offering Pen-DOS from Communications Intelligence Corp, Menlo Park as an option: this enables the pen to be used as if it were a mouse. Another option is a built-in radio data modem from Motorola Inc for wireless networking. The box ships in August; volume fourth quarter.