I was browsing the Atari museum and found this palmtop computer the Portfolio (1989). Quite a neat little device for its day, running an 8088 chip at 4mhz. The Psion was the first palmtop but I think the Portfolio was the first to have DOS compatibility. B)
<a href='http://www.atarimuseum.com/computers/pccomputers/portfolio.html' target='_blank'>http://www.atarimuseum.com/computers/pccom.../portfolio.html</a>