1989 gameboy dmg-01 mod to Dmg-101 sp advance tutorial explanation (part 1 of 3)

Inspiration
http://assemblergames.com/l/threads/gba-sp-inside-dmg-all-you-need-to-know.46158/
Common ground dmg control panel
http://store.kitsch-bent.com/product/common-ground-dmg-button-pcb