Third Stage Boot (Mega CD) Updated Mar 15, 2026 · 6 min read · 0 viewing Log in or register to read the full article. Previous Second Stage Boot (Sega Mega CD) Once the BIOS has been fully initialized it then loads the BIOS program into Program RAM, makes comm... Next Mega CD Engine Pinout (Sega Mega CD) The Mega CD Engine, also known as the Gate Array, controls reading in and generating the overlay gra...