FreyaBIOS is a boot program and hardware abstraction layer for WonderWitch, present in the top-most (last) 64 KB of any WonderWitch cartridge.
It provides the following functionality:
- bring-up code,
- interrupt-based hardware abstraction layer, providing a more user-friendly (and less direct) interface to the WonderSwan hardware,
- 8x8 ASCII and kanji fonts,
- a monitor program, allowing FreyaOS recovery and updates via XMODEM.
Other functionality (like file system access) is instead included as part of FreyaOS' system libraries; some other functionality (like WonderSwan Color support is implemented as part of the development tooling.
As part of its ROM image, FreyaBIOS provides two fonts:
- an 8x8 ASCII font,
- an 8x8 Shift-JIS kanji font - ELISA FONT.
- Exit (INT $10)
- Key (INT $11)
- Display (INT $12)
- Text (INT $13)
- Communication (INT $14)
- Sound (INT $15)
- Timer (INT $16)
- System (INT $17)
- Bank (INT $18)