Psion's 1984-introduced handheld palmtop device was the first Personal Digital Assistant (PDA). A 1993 article by George Fitzmaurice studied spatially aware palmtop computers. The HP 620LX (F1250A, F1259A) is a palmtop computer that runs Windows CE 2.0. It also supported several palmtop computing platforms, including Newton and the Palm OS. The Sharp PC-3000 was a palmtop computer introduced in 1991. It is sometimes referred to as a "palmtop computer". This makes it the world's first palmtop computer. This product was also found in the Sigmarion 3 Palmtop. In 1999, Harold Goddijn left Psion and joined Palmtop Software. The system debuted at "The Lap and Palmtop Expo" on 16 April 1991. It can use OPIE or GPE Palmtop Environment as the graphical user interface. Neither the Palmtop PC nor the Handheld PC were pocket computers. The palmtop will inform soldiers where other friendly forces are in relation to them. Palmtop Software completely changed their name and their image and is now known as TomTom. The first Palmtop PC was the DIP Pocket PC (aka Atari Portfolio) in 1989.