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How many sound channels?


Andre

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Hello!

 

The questions:

 

1) How many sound channels does the 7800 have? I couldn't find anything concerning this, so thanks for your answers (and maybe links how to program sound on the 7800).

 

2) Sprites: Is there a detailed description (how many colors at which resolution etc.) available?

 

Andre

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The soundcard in the 7800 is unfort the same as the one in the 2600 to maintain compatibilty. I believe there are 2 sound voices available (hence the crappy sound on alot of 7800 titles).

 

Some of the Lucas Arts games put a POKEY chip (Atari 800 sound chip) in the cartidge to get better sound, but this was an expensive add on.

 

As for sprite info I dont know that, only that the 7800 could generate and manage ALOT of sprites.

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The build it TIA sound chip gives 2 voices, and a POKEY chip could be added to carts which gave an additional 4 voices.

 

quote:

Originally posted by -^Cro§Bow^-:

Don't forget that while the 7800 could handle lots of sprites...it is also still a scanline renderer like the 2600.

 

It is a scanline renderer, BUT unlike the 2600 the graphics hardware does all the work, not the processor.

 

There is no solid answer to how many sprites the 7800 can handle. Put simply, for each scanline on the screen that graphics chip reads a list of "objects" that appear on that line and copies thier graphics data from memory to a scanline buffer, which will be displayed on the next scanline. So the graphics chip has the duration of one scanline to copy data from memory to the buffer, that's the only real limitation on how many objects (sprites) can appear on each line.

 

Dan

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quote:

Originally posted by Dan Boris:

There is no solid answer to how many sprites the 7800 can handle. Put simply, for each scanline on the screen that graphics chip reads a list of "objects" that appear on that line and copies thier graphics data from memory to a scanline buffer, which will be displayed on the next scanline. So the graphics chip has the duration of one scanline to copy data from memory to the buffer, that's the only real limitation on how many objects (sprites) can appear on each line.

 

Dan

 

I've often wondered this myself. I was interested in creating a test program with a bunch of sprites in different modes to find out the scanline limitation, but there are so many variables (DL's 4-byte or 5-byte direct or 5-byte indirect, how many bytes to fetch, is double-byte fetching on, screen mode, etc...) such that it would be hard to calculate for all possibilities.

 

I think some of this info would be quite useful to know, but it's too variable to calculate. Someone would have to write a lot of boring 7800 code to figure it all out.

 

-John K. Harvey

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