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How many tiles the NGP can handle at same time ?
(05-05-2023, 11:21 PM)Dr.Wily Wrote: The 10 voices or channels is, AFAIK, distributed this way :

- 2 clones of SN76489 with 4 channels each for a total of 6 square waves and 2 noises channels
- Two 6 bits DAC.

Of course, each channel of the SN76489 can play one note at time.

I think there is a common misconception that NGPC has what amounts to 2 independent SN76489 chips.  This is not accurate as far as I can tell.  I have worked on an audio driver for this chip and we have the ability to address volume commands to a left and right register, but I don't think it is possible to play one note on channel 1 to the left and another note simultaneously on channel 1 to the right.

Even though we have stereo, it's still just 4 channels on the Z80.

That is based on what I have seen with getting VGM files to play on the Z80.  Having said that, there are no music trackers for SMS or NGPC that I'm seeing that support composing in a way that you would send a different note to left and right registers simultaneously.

Probably the best test to confirm is to write a quick driver that attempts to send a different note to left/right simultaneously on the same channel and see if it's just one note or 2 playing.  I may be able to put that test together.

The Furnace music tracker sources have this about the T6W:

Quote:an enhanced SN76489 derivative. same 4 channels, but with stereo (soft panning!) and noise frequency being fully independent of channel 3's. this chip was used in Neo Geo Pocket.

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RE: How many tiles the NGP can handle at same time ? - by winteriscoming - 05-06-2023, 01:09 AM

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