At the boot time coputer loads BIOS and MSXBDOS (BIOS for Disc Controlles) from a bood disc. After that COMMAND.COM (MSXDOS).
=== MAGIC SOUND ===
Additional sound board MagicSound is a four channels smapler. Each channel has 8 bit per sample and 6 bits of volume per channel. Computer uses the board for playing STM (Scream Tracker) files. The sample's data containg at the Aleste's memory, that is possible because Aleste have support DMA access from external board to whole Aleste's memory.