Cant find bios files

[TkSilver]

It is interesting to know. In fact this is the only emulator that I have run into where it is not an hle bios but a custom one that is shipped with the emulator. The only other custom bios I have run into in the wild was for the NEO-GEO AES/MVS, but aince it was really a hack to allow for some options that would not normally be allowed (blood settings and region unlocking) it was still a SNK bios and not to be distributed.

I guess I had always assumed that a hand written bios would require something copyrighted by the original hardware manufacturer and that was why hle bios were the only ones distributed.

[Exophase]

It is interesting to know. In fact this is the only emulator that I have run into where it is not an hle bios but a custom one that is shipped with the emulator. The only other custom bios I have run into in the wild was for the NEO-GEO AES/MVS, but aince it was really a hack to allow for some options that would not normally be allowed (blood settings and region unlocking) it was still a SNK bios and not to be distributed.

I guess I had always assumed that a hand written bios would require something copyrighted by the original hardware manufacturer and that was why hle bios were the only ones distributed.

One well known example of a custom BIOS is the old IBM PC clones starting from the early 80s. AFAIK, everything else in the system could be reproduced with off the shelf parts, and the BIOSes were made with clean-room reverse engineering.

There are however two parts of the ARM7 BIOS which aren't included to avoid copyright issues: the encryption table and the GBA logo. I'm not actually sure if the encryption table is copyrightable or not (I don't know where it came from, for one thing) but I didn't want to take that risk. So that's why it's not there. AFAIK, the GBA logo is only ever used to compare with the one in the GBA cartridge header to check if it's a valid GBA game that was inserted. Here DraStic just copies that from the GBA ROM, so it's not a problem.

I think other emulators (that don't require the original BIOS) use HLE BIOSes because they're easier to write than custom ones. The latter requires some kind of toolchain for building binaries that can run on the emulated platform, and there's a good chance they'll require at least some assembly language (DraStic's are written entirely in assembly). HLE BIOSes are also more efficient. But DS games don't really spend much time in BIOS functions, so the performance benefit isn't really tangible.