The Nintendo DS line (often called the DS family) is a line of handheld game consoles developed and sold by Nintendo from 2004-present. It succeeded the Game Boy Advance line and was succeeded by the Nintendo 3DS line in 2011.
Initially released as an experimental platform ancillary to the Game Boy line, the Nintendo DS line soon replaced it as Nintendo's flagship handheld device family. Featuring and interacting with many of the game series that are seen on the company's home console lines, the DS line has often represented the bulk of the company's unit system sales throughout the course of its history.
DeSmuME attempts to emulate, as faithfully as possible, the Nintendo DS and Nintendo DS Lite handheld game consoles (NDS). There is a lots of documentation and info on the homepage, and download for mac is located here.