A handheld PC, or H/PC for short, is a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a palmtop computer. The first hand-held device compatible with desktop IBM personal computers of the time was the Atari Portfolio of 1989. Other early models were the Poqet PC of 1989 and the Hewlett Packard HP 95LX of 1991. Other DOS-compatible hand-held computers also existed. Some handheld PCs use Microsoft's Windows CE operating system, with the term also covering Windows CE devices released by the broader commercial market.