would this work?

[Atariman]

Hmm... I was just doing a little bit of thinking. (No, it's not that new of a thing for me. I'm starting to get the hang of it) I recall reading that the 7800 did not have enough room inside of its case to put the "new and improved" sound processor inside, so they put it in the games instead. Since this was done, wouldn't it be possible to design a different sound processor (designed to be compatible with the 7800, of course), slap it inside a homebrewed cartridge, and use it instead? Then, in theory (whether I'm wrong or not) couldn't you design MUCH better sound in homebrewed 7800 games? I'm pretty stupid when it comes to the actual workings of each system, so tell me what's up.

[eric_ruck]

I was wondering the same thing. I have a friend big into FPGA's...I wonder if it would be possible to use one FPGA or similar device to act as both the ROM for the game as well as the sound chip. I also wonder if it would be adequately economical.

 

Eric

[Atariman]

I was also wondering if it would be possible to add something else in addition to or instead of the sound chip to improve some other area of the 7800. Could you add more RAM, or is this "expansion" spot so to speak on the cartridge reserved for the sound alone?

[Inky]

Heck,I wouldn't mind a 'Pokey' cart you could pop into the cart slot.

[+Mitch]

I was also wondering if it would be possible to add something else in addition to or instead of the sound chip to improve some other area of the 7800.  Could you add more RAM, or is this "expansion" spot so to speak on the cartridge reserved for the sound alone?

 

Sort of yes.

Atari games maxed out at 128k plus either a Pokey sound chip, 8k/16k RAM, or 16k additional ROM.

 

Mitch

http://atari7800.atari.org

[DanBoris]

If you built your own 7800 cartridge you could actually do quite a bit to expand the 7800 capabilities. Unlike the 2600, the 7800 brings the full processor bus out to the the cartridge port, addresses, data, and control signals. The system uses the lowest 16K of the memory space, so the cartridge can do whatever it wants with the rest of the space. The expanded sound capability is possible because they also brought an audio output line to the cartridge slot. Any audio put onto this line is mixed with the audio from the 7800's internal sound chip. So you could add almost any kind of sound chip to a 7800 cart.

 

A cool thing to do would be to make a cartridge that uses the Quad-pokey chips that where designed for the Atari arcade machine. This way you could get 16 additional sound channels instead of just 4 with a normal pokey.

 

Dan

[Inky]

If you built your own 7800 cartridge you could actually do quite a bit to expand the 7800 capabilities. Unlike the 2600, the 7800 brings the full processor bus out to the the cartridge port, addresses, data, and control signals. The system uses the lowest 16K of the memory space, so the cartridge can do whatever it wants with the rest of the space. The expanded sound capability is possible because they also brought an audio output line to the cartridge slot. Any audio put onto this line is mixed with the audio from the 7800's internal sound chip. So you could add almost any kind of sound chip to a 7800 cart.  

 

A cool thing to do would be to make a cartridge that uses the Quad-pokey chips that where designed for the Atari arcade machine. This way you could get 16 additional sound channels instead of just 4 with a normal pokey.

 

Dan

 

Then here's another question. How about a better video chip. Would that be a possibility?

[DanBoris]

Then here's another question.  How about a better video chip.  Would that be a possibility?

 

You couldn't do this by just using the cartridge slot since there are no video signals brought out to the cart connector. In theory you could run a cable from the cart to the expansion connector (if your 7800 has one) and use the composite video input on that connector.

 

Dan

[ubersaurus]

So in theory, you could have a 7800 with SNES sound...that'd be crazy sweet.

[Atariman]

so if you could access the composite connection through the expansion slot, could you then increase the resolution? Then, in theory, couldn't you make yourself a SWEET homebrew video game? (RPG or something cool like that)

[Atariman]

Hey, Mitch, you said

Atari games maxed out at 128k plus either a Pokey sound chip, 8k/16k RAM, or 16k additional ROM.

 

So, by that do you mean that that's the absolute maximum game size that you could have, or do you mean that the largest they ever produced was this size? If it is the max, is there ANY way to increase the RAM, or is it some other limitation? I'm just wondering just how big a 7800 game could potentially be (even if the 7800 needed some sort of "expansion unit" so to speak added on to the cartridge itself)

[+Mitch]

Hey, Mitch, you said

Atari games maxed out at 128k plus either a Pokey sound chip, 8k/16k RAM, or 16k additional ROM.

 

So, by that do you mean that that's the absolute maximum game size that you could have, or do you mean that the largest they ever produced was this size? If it is the max, is there ANY way to increase the RAM, or is it some other limitation? I'm just wondering just how big a 7800 game could potentially be (even if the 7800 needed some sort of "expansion unit" so to speak added on to the cartridge itself)

 

No, that's just the biggest Atari ever made. From what I understand, you could go up to a 1 megabyte ROM using the standard Atari bankswitching method. I don't think you could really add much more RAM though, since you would need to map it somewhere and there's a limited amount of available addresses.

 

Mitch

http://atari7800.atari.org

[eric_ruck]

No, that's just the biggest Atari ever made. From what I understand, you could go up to a 1 megabyte ROM using the standard Atari bankswitching method. I don't think you could really add much more RAM though, since you would need to map it somewhere and there's a limited amount of available addresses.

 

Sure you could, you could build something like a DMA where you plug a starting address of any length into a register or series of registers, then read or write serially from a shifted data register. I believe that's how you read the ROM on a Lynx.

 

Eric

[DanBoris]

In theory you could add an almost unlimited amount of RAM and ROM in a 7800 cart by using bank switching. For example if we mapped our ROM into a 16K address block, and our RAM into another 16K address block, then setup a 8-bit latch (256 different combinations) for each to determine the bank you would get:

 

256 * 16K = 4096K of RAM and ROM

 

If you did two 8-bit latches for each your would get:

 

65536 * 16K = 1048576K

 

Of course with that much RAM in cartridge you would probably burn out the 7800's power supply!

 

Dan

[+Mitch]

Doh.

For some reason I completely forgot about bankswitching the RAM.

 

Mitch

http://atari7800.atari.org