7800 sound - need clarification.

[Streck]

(And I'm not asking this in the 7800 forum because I've the idea that it doesn't see nearly as much traffic as here.)

 

So I'm playing 5200 and 7800 games in the MESS32 emulator. And when I load a 5200 ROM I see the sound described as simply:

 

1xPokey 1.789790

 

When I load a 7800 ROM the sound shows as (exactly as):

 

TIA

1xPokey 1.790000 MHz.

 

What, precisely, does this mean? Are the emulator people injecting Pokey sound into 7800 games where none originally existed? Or does it mean nothing at all? Can anyone well-versed in this emulator help me out?

[JB]

It means that 2 of the 7800 carts had a POKEY in them and the MESS people can't document things worth beans.

...

Sorry. I have a severe dislike for MESS.

[ApolloBoy]

Those 2 games are Ballblazer and Commando. They both have great gameplay and great music!

[Streck]

It means that 2 of the 7800 carts had a POKEY in them and the MESS people can't document things worth beans.

But the games I was playing were Ms. Pac-Man and Robotron 2084. Or did you mean something else?

[oesii]

It means in order to emulate as many 7800 carts as possible they had to include the standard sound chip emulation plus the pokey sound chip emulation (which only 2 carts use). But no extra sounds are being inserted, it's just there for compatability.

[DanBoris]

As the original author of the MESS 7800 driver I can address this. There are data structures in the MESS drivers that describe the hardware in a system, and this is where the descriptions of the sound hardware come from. Since some 7800 games include a POKEY chip it is definined in the driver as being part of the 7800 hardware, then enabled or disabled based on the cart that is loaded.

 

Since MESS evolved from MAME there are no provisions for changing the hardware of a system based on the roms that are loaded into it, it's not something that comes up a lot. This is why it reports the Pokey even if you are running a cart that doesn't contain a Pokey.

 

Dan

[Streck]

As the original author of the MESS 7800 driver I can address this. There are data structures in the MESS drivers that describe the hardware in a system, and this is where the descriptions of the sound hardware come from. Since some 7800 games include a POKEY chip it is definined in the driver as being part of the 7800 hardware, then enabled or disabled based on the cart that is loaded.  

 

Since MESS evolved from MAME there are no provisions for changing the hardware of a system based on the roms that are loaded into it, it's not something that comes up a lot. This is why it reports the Pokey even if you are running a cart that doesn't contain a Pokey.

Thank you very much. If the emulator is emulating only TIA sound for TIA-only 7800 ROMs, then, I guess I have a more general question: How accurate is the TIA sound emulation? I only ask because when I first heard the sound (for the two games I mentioned before) I was rather surprised at how decent they sounded, especially given the derision I've heard the TIA chip subjected to over and over again. I'd hate to think I was hearing something considerably better than what an actual 7800 system put out.

[DanBoris]

As far as I know the TIA emualtion is pretty accurate. The TIA emualtion code has actually been around since 1996 and has been tweaked a lot since then.

 

Dan