WonderWitch/FreyaBIOS

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.

Revisions

- FreyaBIOS 1.0.0

Fonts

As part of its ROM image, FreyaBIOS provides two fonts:

• an 8x8 ASCII font,
• an 8x8 Shift-JIS kanji font - ELISA FONT.

Interrupts

• 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)

Freya Monitor

TODO