BC: what does it do?

I have read on hackmii that BC is very similar to boot1, and thus probably loads boot2.what does it do and (as bootmii is a boot2 patch) is it affected by bootmii?

I don't have the full story for BC, but IIRC it is used to load MIOS. You could consider it a bootloader for MIOS.

For reasons not quite clear, the System Menu does not directly load MIOS to boot a GameCube game. Instead, it launches BC, which is almost identical to boot1. The only major difference is that it sets a register which slows down the Hollywood clock speed to that of the Flipper (found in the GC).

When boot2 runs, it checks that clock speed; if it's in the slower mode, it starts MIOS instead of the System Menu.

Unless we do something to specifically prevent it, BC will load BootMii, yes. Also, new versions of BC (like those released several months ago) will refuse to load BootMii, so that will actually break GC compatibility :/

are those the ones from 3.3? will you guys be making an app using bootmii to specifically downgrade BC? (not anything else so it wont help piracy) I love my gamecube games :-) also, is gamecube mode under ios? what starlet code runs?



Edited 2 time(s). Last edit at 01/29/2009 07:46PM by metroid_maniac.

Yes, those are the ones from 3.3. We'll deal with the BC vs BootMii compatibility issue when we actually release the thing. GameCube mode runs under MIOS.

so is MIOS starlet code then?

Yup (hence MIOS).

so


system menu detects GC game and loads BC
BC changes clock speed and loads boot2
boot2 detects clock speed and loads MIOS
MIOS loads gc game

MIOS actually starts some powerpc code embedded into its ELF and this powerpc code loads the gc game then.

Quote
bushing
For reasons not quite clear, the System Menu does not directly load MIOS to boot a GameCube game. Instead, it launches BC, which is almost identical to boot1. The only major difference is that it sets a register which slows down the Hollywood clock speed to that of the Flipper (found in the GC).

When boot2 runs, it checks that clock speed; if it's in the slower mode, it starts MIOS instead of the System Menu.

Does that mean that it would be possible to install a patched BC and BOOT2 to slow down the clock to something like a fraction smaller than what the Wii uses ordinarily, as opposed to the value that GameCube uses, so that GameCube games can load using the Wii clock speed (minus 0.01 or something), and have a much faster clock speed in GameCube mode..?



Edited 1 time(s). Last edit at 02/14/2009 01:58PM by SoraK05.

Is there even anything that prevents us from loading gamecube code while running at full spped in WiiMode?

Argh, nothing, I made a mistake at reading his post.

So games would not work in my opinion

Quote
daniel_c_w
Is there even anything that prevents us from loading gamecube code while running at full spped in WiiMode?

Anyway, I do not see the reason..
For example the overclocked DS:
http://www.youtube.com/watch?v=gL8xi_CgIJ4



Edited 5 time(s). Last edit at 03/30/2009 08:00PM by IcyVeins.

hmm i have 3.3j (V1) which was downgrader through ARC to 3.2j which obviously has the new BC and MIOS, I sure hope they release a downgrader!

why?

Is there a way to fix this in BootMii without having to use a SD binary?

If there is, here's an idea.

If anything tries to start BC, your code traps it, sets the register, and goes to normal boot2 from there. Essentially, skip BC.

well, i do love my gamecube games.

ok but if you have bootmii replace the bc you would need to make a loader for gc games in that code so you wouldnt lose the feat.

It will be taken care of. Next question?

If the BC can underclock the CPU and GPU, would it be possible to modify the BC to overclock the the CPU and GPU?

Quote
timmy112
If the BC can underclock the CPU and GPU, would it be possible to modify the BC to overclock the the CPU and GPU?

Why does BC have any special privileges? Bootmii probably could under/overclock anything.