[4-bit PCM audio on the 2600?]

Theoretically you should be able to create any frequency by mixing the closest two frequencies the TIA can create.

 

In my last experiments with this I didn't have any luck. Maybe it's nice on a per-frame basis, but I tried doing it every few scan lines and it did not have the effect I anticipated. I am not sure how the Atari 2600 derives phase for its waveforms, but I think the problem is related to that.

[Finding enough 2LK kernel time...]

One trick I used (in a 2 player + background kernel) was to pad the player graphics data with 0 up to 256 bytes. Then, no logic had to be used in determining where to start/stop drawing the players; the kernel just loaded the vertical positions of the players, added a per-line decremented value and used that as an offset in the player table. If you have some ROM to spare, that is a good way to save some cycles in the kernel.

[4-bit PCM audio on the 2600?]

I made a music player that incorporates 4-bit PCM playback for percussion. It's probably not very useful for games since a lot of raster time is used to decode bytes into pairs of samples.

 

But if you have a kernel that can realistically only use half of all the scanlines, or maybe just don't pack samples together, I can see something like it being useful in a game. The trick, then, is to play a few samples at correct/nearly correct rates and intervals during your vblank code. For percussion in particularly it doesn't need to be very exact. It's more of a problem if you have pitched sounds.

 

Some examples: https://soundcloud.com/boomlinde/oil https://soundcloud.com/boomlinde/quantum-branch

Source code: https://bitbucket.org/boomlinde/vcs-music/src

[Jupiter Sumo (new game)]

NICE concept, beautiful work, thank you! Plans for cart release?

Thanks! I have no plans for a cart release, but if anyone feels inclined to, they are free to do it. If enough people express an interest I will consider doing it myself, but I would need some help on where you can get cartridges and 2k ROM boards manufactured in small quantities.

[Jupiter Sumo (new game)]

That looks like a fun two-player game. Is it two-player only?

 

..Al

Yes, two players only, but I am open to ideas for single player game modes!

[Jupiter Sumo (new game)]

Hi,

I just finished my first Atari 2600 game. I would call it a mix of Jupiter Lander and cue sports.

 

http://boomlin.de/gopher/h/jupitersumo.html

 

 

It currently runs in PAL, but changing it to run in NTSC should be a matter of changing a few variables in the code and the playfield data. Any such contribution is welcome and will be merged with the rest of the code.

[Harmony cart "THANK YOU!" thread]

Mine came with the mail yesterday. Well packed, and worked perfectly! Really great value for the money spent. i've been exploring the forum and noticed people have been using the ARM to offload the 6507. Is there a way to use the USB port to write arbitrary values into sections of mappable memory while it is running, or is it just for ROM burning?