FDS BIOS Dumper

This program dumps the Famicom Disk System's BIOS ROM (8KiB) onto a disk. Now you can legally obtain a dump from original hardware!

Usage

1. Load the program. Drive emulators such as the FDSKey are recommended for easy access after dumping. Physical disks will work, but dumping capabilities may be limited by write protection measures added to later disk drives.
2. A menu will appear after calculating the CRC32 checksum of the BIOS. Use the Select button to pick between 2 dumping modes:
   1. Fast - 1x 8KiB file (recommended for drive emulators, or drives with write protections disabled)
   2. Slow - 8x 1KiB files (recommended for drives with write protections present)
3. Press the Start button to begin dumping the BIOS.
4. Keep the disk inserted until the "OK!" message appears.
   1. Should any issues occur, an error message/code will be displayed. Make a note of the error number and reinsert the disk. The program will automatically retry from the file it failed on.
5. Eject the disk and extract the dumped BIOS. The extraction/reconstruction process is outside the scope of this project.
   1. Fast - DISKSYS0 contains the entire 8KiB.
   2. Slow - DISKSYS0 through DISKSYS7 contain 1KiB each.

BIOS Versions

Original RAM adapters and the Sharp Twin Famicom:

Origin	Rev.	CRC32	Bootup Logo	Drop Shadows?	Hidden Credits
Older RAM adapter	01	1C7AE5D5	"Nintendo"	Yes	Programmer credit only
Later RAM adapter	01A	5E607DCF	"Nintendo"	No	"2C33", "DEV.NO.2" lines added
Sharp Twin Famicom	02	4DF24A6C	"FAMICOM"	Only on logo	"2C33", "DEV.NO.2" lines added

To access the hidden credits (P1 controller):

1. Hold Start + Select at power-on/reset. (Easier with no disk inserted)
2. Release Start + Select, then hold Right + A. This must be done before the RAM check screen appears.

See https://tcrf.net/Family_Computer_Disk_System for more details.

Here are some known aftermarket variations, for completeness (not guaranteed or useful to run on):

Origin	CRC32
Animal Crossing, Wii/Wii U VC	0BA8D953
Famicom Mini (GBA)	6C1BCC70
3DS VC	17E30673
3DS VC (Nazo no Murasamejou)	34E2B2C7
Game & Watch: SMB	7D8F0C3C
PowerPak	93B3BD15
Everdrive N8(?), N8 Pro	CE3A3A3D

Error Numbers

TODO: Print messages for common errors?

Please refer to the error list on NESdev Wiki. The displayed error number is already in Binary-Coded Decimal (BCD) format.

Building

The CC65 toolchain is required to build the program: https://cc65.github.io/ A simple make should then work.

Acknowledgements

• Jroatch-chr-sheet.chr was converted from the following placeholder CHR sheet: https://www.nesdev.org/wiki/File:Jroatch-chr-sheet.chr.png
  • It contains tiles from Generitiles by Drag, Cavewoman by Sik, and Chase by shiru.
• Hardware testing was done using a Sharp Twin Famicom + FDSKey.
• The NESdev Wiki, Forums, and Discord have been a massive help. Kudos to everyone keeping this console generation alive!