Gaming GBA games on DS: Legacy GB sound channels

[Xan0906]

My guess is that, since the DS lacks the GBC CPU, those channels are emulated on one of the DS processors while playing GBA games. Presumably it's also an issue for GBA ports on the DS, like the Mega Man Zero collection.

Originally I thought this would impact sound quality on GBA games that use these channels, but I did a comparison recently and found the difference to be not really noticeable. Is there any information on how these legacy channels are performed on the DS?

 

[Ozito]

I beg your pardon for my ignorance, but what does the gbc cpu have to do with gba games?

 

[Jayro]

The DS and DS Lite can play GBA games, and only GB/GBC through emulation.

 

[Foxi4]

The two posters above don't seem to be familiar with the matter so I'll elaborate. The Game Boy/Game Boy Colour were both powered by a custom Z80-like CPU called Sharp LR35902. This processor was later implemented in the GBA for the sake of backwards compatibility as well as an additional sound coprocessor in GBA Mode, used to generate legacy 8-bit sound.

This is just an assumption of mine, but I believe that if it's at all supported, it's probably emulated on one of the ARM cores or one of the chips offers equivalent functionality and as such the chip was completely skipped.

I just had a look at GBATek but I'm afraid that there's no information about LR35902 or Z80 on there in the DS section, leading me to believe that its functionality either has been skipped or it's performed by the ARM7 natively.

 

[bobmcjr]

My guess is that, since the DS lacks the GBC CPU, those channels are emulated on one of the DS processors while playing GBA games. Presumably it's also an issue for GBA ports on the DS, like the Mega Man Zero collection.

Originally I thought this would impact sound quality on GBA games that use these channels, but I did a comparison recently and found the difference to be not really noticeable. Is there any information on how these legacy channels are performed on the DS?

The NDS Phat/Lite appears to contain the GBA sound hardware, meaning that both PCM channels (A and B) as well as the analogue "chippy" 8-bit-like channels are included. The "chippy" channels are just coincidentally backwards compatible with GB/C games, but are primarily part of the GBA's sound chip. The Z80 CPU appears to have nothing to do with this. For more info see here: http://nocash.emubase.de/gbatek.htm

Edit: could be wrong, this is mainly based on what I understood from that link.

 

[Foxi4]

The NDS Phat/Lite appears to contain the GBA sound hardware, meaning that both PCM channels (A and B) as well as the analogue "chippy" 8-bit-like channels are included. The "chippy" channels are just coincidentally backwards compatible with GB/C games, but are primarily part of the GBA's sound chip. The Z80 CPU appears to have nothing to do with this. For more info see here: http://nocash.emubase.de/gbatek.htm

Edit: could be wrong, this is mainly based on what I understood from that link.

Yeah, that's pretty much what I gathered as well.

 

[nl255]

I beg your pardon for my ignorance, but what does the gbc cpu have to do with gba games?

Simply put, when the GBA came out it had GBC hardware in it for backwards compatibility. Thus some game developers took advantage of it and use the GBC sound hardware in their GBA games. So when the DS came out they had to either keep the GBC sound hardware or emulate it otherwise quite a few GBA games would not work on the DS and Nintendo didn't want to do like MS did with the 360 XB1 emulation where only a small percentage of older games would work.

 

[BORTZ]

Simply put, when the GBA came out it had GBC hardware in it for backwards compatibility. Thus some game developers took advantage of it and use the GBC sound hardware in their GBA games. So when the DS came out they had to either keep the GBC sound hardware or emulate it otherwise quite a few GBA games would not work on the DS and Nintendo didn't want to do like MS did with the 360 XB1 emulation where only a small percentage of older games would work.

Oh weird I never thought about that before. So GBA devs had access to the stuff in GBC mode. But the DS doesnt have access to GBA stuff in DS mode right? Why is that?