Jaeden Amero has updated his Introduction to Nintendo DS Programming which is a manual for all you wanna-be DS homebrew developers out there. The manual covers topics important to the homebrew community such as the legality of homebrew and the politics behind it, displaying backgrounds on both screens, sprites and some aspects of game mechanics.

According to the author, Introduction to Nintendo DS Programming v4.0 features a brand new section on VRAM exploration in the manual's Appendix A. The section includes VRAM usage and layout. If you're having problems with designing 2D graphics engine, this manual version would be a lot of help. Aside from that, Introduction to Nintendo DS Programming v4.0 has an updated page layout for easier reading.