DSx86 is a PC/DOS emulator for Nintendo DS written by Patrick Aalto. It’s purpose is to allow you to run old DOS games on your Nintendo DS game console. Some of the older games run quite good and bring back memories.

Release notes:

This version has only one small fix, the smooth scaling changes I made in the previous version introduced a screen flickering problem when attempting to scroll the smooth-scaled screen. This also happens when the Touch Pad Mouse cursor got near the screen border in modes that do not need scrolling, like in 640×480 mode. This problem was caused by my changing the REG_BG3Y hardware scaling register after the screen blitting function, and as the screen blitting took longer than one VBlank period, this change also occurred at a time when the screen was already active. This register should not be changed during active screen scanning time, or flickering will occur. In this version I moved the setting of this register to before the screen blitting code, so there should not be any flickering any more.

http://dsx86.patrickaalto.com/