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"Dragonfly" my version of the Atari 7800 SD cartridge


rj1307

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1 hour ago, RevEng said:

If pokey IRQ was hooked up to IRQ in cart designs, then yes. This isn't the case with present designs, as far as I'm aware. Perhaps it is, in rj1307's prototype?

I would imagine that MARIA will mask IRQ when drawing the screen and the 6502 will not be allowed to update digital samples at regular intervals during this time. I could be wrong, but I would guess that MARIA takes priority over anything in the system. It may work while the screen is blanked or maybe when there isn't a lot on the screen, though.

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1 minute ago, batari said:

I would imagine that MARIA will mask IRQ when drawing the screen and the 6502 will not be allowed to update digital samples at regular intervals during this time. I could be wrong, but I would guess that MARIA takes priority over anything in the system. It may work while the screen is blanked or maybe when there isn't a lot on the screen, though.

Great point ?

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Maria won't exactly mask a pending IRQ, but rather she fully halts Sally during rendering. As long as whatever device is triggering the IRQ will hold IRQn low until acknowledged, Sally can deal with it whenever rendering is over.

 

Regarding sample playback, a small FIFO is a good idea and wouldn't use too many gates. Sally could get an optional IRQ when it's empty, or near empty, and then copy in more sample data when it's convenient for her. I see a small crystal on the board - if it could be clocked by this (with a programmable rate using a phase accumulator), then you don't have to deal with PHI2 wobbling.

 

But again - if you're all continuously going down this route I recommend working together to spec out a new community standard for audio hardware on a CPLD or FPGA rather than it going in a thousand different directions on every new utterance of a flash card or expansion device.

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2 hours ago, TailChao said:

Maria won't exactly mask a pending IRQ, but rather she fully halts Sally during rendering. As long as whatever device is triggering the IRQ will hold IRQn low until acknowledged, Sally can deal with it whenever rendering is over.

 

Regarding sample playback, a small FIFO is a good idea and wouldn't use too many gates. Sally could get an optional IRQ when it's empty, or near empty, and then copy in more sample data when it's convenient for her. I see a small crystal on the board - if it could be clocked by this (with a programmable rate using a phase accumulator), then you don't have to deal with PHI2 wobbling.

 

But again - if you're all continuously going down this route I recommend working together to spec out a new community standard for audio hardware on a CPLD or FPGA rather than it going in a thousand different directions on every new utterance of a flash card or expansion device.

I guess it gets too complex and complicated, it was supposed to be a simple project.

 

 

2 hours ago, Muddyfunster said:

I can also send you a work in progress Danger Zone Rom that has @Synthpopalooza 's funky Pokey special + Tia stuff to test if you like. 

 

Couldn't get it to run on Mateos.

 

Of course, I'll be happy to check it, send it to me at PW.

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RevEng:

 

I tried putting this into my code:

 

CHANNLTBL:
	.byte $10,$11,$12,$13

 

This is intended to address the last 4 channels, by offsetting them 16 bytes from the start of the first POKEY.  How would I go about modifying that pokeysound code to allow addressing of $10 thru $13?  I'd basically use $00 to $03 for the first four and $10 to $13 for the last 4.

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It's not my code, so I'm not really authoritative on it. It looks like first you'd need to add an extra 4 bytes of memory allocations for pretty much everything that currently has 4 bytes, to track the extra 4 voices. Then you'd look for instances of "#$03" being loaded that are used for loops, and change those to "#$07".

That should get you started, though there's probably other stuff that needs to be done that I'm missing on first glance.

 

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I was about to make a comment about contacting the XM team, but that was before I heard the news about Curt's passing. After giving this some thought, I think Curt would want us to keep moving forward. So I will share my knowledge about the issue of the XM sound chips.

 

Years ago, Curt contacted me regarding Concerto and he proposed a way that the two could play nice together. Even if the future of the XM project isn't clear, I will say that a way for a cart to disable the sound chips of the XM was worked out back then. I don't think this method has been shared publicly, so for now I won't disclose details, but just say that I think it is probably safe to go forward with a second POKEY at $0460. If the XM project does continue, any games that wish use a second POKEY at $0460 could include this method for disabling the XM sound chips.

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Why on Earth do folks cling to the request to play 2600 games on these 7800 SD projects? Get a HARMONY or an UNO for that. Let these projects purely support the complicated 7800 as it is, and maybe incorporate a couple of things the XM would've tackled. That's enough complexity right there.

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7 hours ago, Lynxpro said:

Why on Earth do folks cling to the request to play 2600 games on these 7800 SD projects? Get a HARMONY or an UNO for that. Let these projects purely support the complicated 7800 as it is, and maybe incorporate a couple of things the XM would've tackled. That's enough complexity right there.

Preach it!

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19 hours ago, Lynxpro said:

 <Cough> <Cough> Not produced in well over a decade or more, doesn't have any XM/XBoard features, etc. <Cough> <Cough>

The question was "why is it brought up."

Not "does it make sense today."

?

You also missed the point that the CC2 cost $250 at the time.

 

?

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54 minutes ago, Mitch said:

The CC2 never cost $250 new , it was $200, later $150 and it does include many of the XM/XBoard features. (HSC support, POKEY, extra cart RAM)

 

Mitch

 

And the last of the CC2's that Chad couldn't sell got discounted even further towards the end if I recall correctly.

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1 hour ago, Mitch said:

The CC2 never cost $250 new , it was $200, later $150 and it does include many of the XM/XBoard features. (HSC support, POKEY, extra cart RAM)

 

Mitch

In that case, I need to talk to Chad, because pretty sure I paid $250.

 

Nope, I lied...

$210 with shipping...

Just checked my email receipt.

For some reason I was thinking $250.

My bad on that..

 

Edited by desiv
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