Can 2600 games use the XM?

[+Propane13]

Since there are a lot of XM-specific threads here, I thought I'd have this be its own thread, since it'll probably be a simple answer, and then die.

So, the question is-- can 2600 games use the XM if they were programmed to?

 

I'm guessing the hardware locations for the SID chip/etc are still valid. Yes?

 

-John

[+GroovyBee]

Some of the features rely on the HALT signal on the 7800's cart slot so you couldn't use those. You could access POKEY and the YM sounds chips without any problems I expect. You wouldn't want to enable the HSC because it would clash with SARA.

[Bakasama]

Pokey enhanced 2600 games? I find that very interesting. Sounds like even more reasons to get an XM.

Edited February 20, 2011 by Bakasama

[+HammR25]

Pokey enhanced 2600 games? I find that very interesting. Sounds like even more reasons to get an XM.

2600 Pac-Man hacked with Pokey sound. It would be just like playing the real thing.

[Mord]

Some of the features rely on the HALT signal on the 7800's cart slot so you couldn't use those. You could access POKEY and the YM sounds chips without any problems I expect. You wouldn't want to enable the HSC because it would clash with SARA.

 

Interacting withe the chips and actually getting the output from them would be different stories however. There is no audio line on 2600 cartridges so unless there's another method to pulling the sound out for others to hear...

[Phredreeke]

Yes but does the 7800 disable the audio pin while in 2600 mode?

 

Then again, if you're using a 7800, why not just code for the 7800 in the first place?

[+GroovyBee]

Interacting withe the chips and actually getting the output from them would be different stories however. There is no audio line on 2600 cartridges so unless there's another method to pulling the sound out for others to hear...

 

I assumed the OP would plug the XM into the 7800. In which case, sound from POKEY and YM2151 would be routed through to the audio circuit (via the XM's bottom cart connector) even if its a 2600 cart in control.

[+GroovyBee]

Yes but does the 7800 disable the audio pin while in 2600 mode?

 

Nope! Standard 7800 sound comes from TIA in both 7800 and 2600 modes.

[Mord]

I assumed the OP would plug the XM into the 7800. In which case, sound from POKEY and YM2151 would be routed through to the audio circuit (via the XM's bottom cart connector) even if its a 2600 cart in control.

 

Ah that's true. This is why I try not to post right after waking up.

[+GroovyBee]

The other thing you'll be able to do is get POKEY comms going as well as the sound. Then you can have multiplayer 2600 games across machines then.

 

When the dust settles (I'm flat out at the moment) I'll look into adding a 2600 example. I need to get my feet wet with the 2600 at some point .

[+Propane13]

Crap, I just had a bad thought.

 

If I remember correctly, the 2600 is limited to 13 address lines, whereas the 7800 has no such limitation (i.e. it has the full 16).

 

That means, I think, that if POKEY is at $4000, and we try to LDA $4000, it may not work.

I think that 13-address line architecture will resolve that location to $F000, and pull data from there. Is that correct?

 

I'd like to request a hardware guy to let me know if I'm nuts.

 

-John

[+GroovyBee]

POKEY is at $450 in the XM. So it should be OK.

[+Propane13]

That information brightens my day.

Is the yamaha sound chip also in the 0XXX block?

 

-John

[+GroovyBee]

Is the yamaha sound chip also in the 0XXX block?

 

Yep! The control registers to enable them are in that range too.

[tep392]

Pokey enhanced 2600 games? I find that very interesting. Sounds like even more reasons to get an XM.

2600 Pac-Man hacked with Pokey sound. It would be just like playing the real thing.

 

Did you see this hack that I did as a joke? It's the exact opposite. 7800 Pac-man with 2600 sound.

Edited February 21, 2011 by tep392

[Lendorien]

2600 games with pokey sound would be interesting indeed. What a weird thought. I challenge someone to do it. Even just as a tech demo!

[+Propane13]

I was debating just taking my Marble Madness framework and dumping in a few of the Pokey sounds from my 7800 Arkanoid Pokey code.

Of course, I wouldn't be able to test it.

 

So, I'd need 2 things to try this:

1) The equates for POKEY on the XM (is there an xm.h file available?)

2) Someone with an XM that would be willing to try it out for fun.

 

So, XM team, does #1 exist (and if not, how soon would it be available)?

 

-John

[+GroovyBee]

1) The equates for POKEY on the XM (is there an xm.h file available?)

 

Write $10 to $470 to enable POKEY (don't set other bits)

Base address of POKEY is $450

 

2) Someone with an XM that would be willing to try it out for fun.

 

Unfortunately 2600 compatibility with XM at register level is very low down on my list of things to try out. However, I can't see a reason why it wouldn't work. You'd also have to take into account that the POKEY isn't running at 1.79MHz in your tone divider calculations.

[+GroovyBee]

POKEY in the XM matches the XBOARD spec here :-

 

http://www.x-game.se/products/xboard.htm

 

The other control register bits do other things on XM.

[[d2f]Iggy*SJB]

Base address of POKEY is $450

 

That's kind of expensive, isn't it?

 

 

(Ok, bad joke, but someone had to say it, didn't they?)