POKEY 16-bit mode and other AUDCTL settings - A7800 emulation

[RevEng]

Thanks for that evaluation - it definitely gives me somewhere to start with the remaining improvements needed.

[Synthpopalooza]

One other bit of good news is that standard 16-bit mode in all distortions seems to be working now.  It needs a further check on my end but I'm certain it's good.  

[Synthpopalooza]

Confirmed, standard 16-bit on C distortion is 100%.  Gave it the ultimate benchmark:  The "Have You Played Atari Today" jingle which uses this setting.  On the older A7800 release it had a horrid banjo type sound.  It's now 100% to real hardware.

 

Posting up the pokeyplayer for EXO.  Everything is 100% to real hardware except as marked:

 

Area 2:  A minor issue, I don't think the fuzziness is being done on the $4x/$Cx two-tone bass.  It still sounds good though.  Keep in mind I am still in the middle of documenting all the settings in this mode (there are at least about 9 or 10!)

Area 3:  The two-tone $Ax distortion 1.79+64 notes at the beginning are missing on some notes.  This is actually the same issue that presented itself in the most recent releases of Altirra and PokeyMax.  Once it goes to the CSAVE bell sound in the middle everything is ok.

 

Area 5, and title music:  The two-tone $Ax distortion 1.79+15 note arpeggio is missing on some notes, same issues as above.  Also, $2x 1.79 bell is playing in the wrong octave and waveform

 

Launch bay:  The fuzzy $4x/$Cx two tone bass is working ok, $2x @1.79 bell lead is wrong waveform and octave again, same issues as above in Area 5.

 

Launch and credits:  Reverse 16 $4x guitar is good!  Again, wrong octave on $2x @1.79 mhz bell.

 

Game Over:  Has the same issue with the $2x @1.79.  Also, may have to check against real hardware on the Reverse 16 $Ax bass with $Ax playing on second channel.  Seems unstable, but this instability may also be present in real hardware.  This however is a minor issue.

 

 

 

exo-pokeyplayer.78b.a78 exo-pokeyplayer.78b.bin

[Synthpopalooza]

So, further testing and A7800 is about 98% to 99% good to real hardware.

 

I am putting efforts now (in addition to documenting new POKEY settings) to Dragonfly stereo POKEY.  I know actual emulation is a ways away for this, but I am going to work up actual examples anyway towards that eventuality.  It'll be a rendition of music from Metroid. 

 

I do need a reminder tho ... how do I edit the .128 file to make a binary addressable by the Dragonfly, for $440 and $450 POKEY?  I've got the music player code right, I'm certain ...

[Ecernosoft]

On 7/17/2019 at 12:51 AM, Synthpopalooza said:

Another obscure function of POKEY ... is that there is a means of playing sampled audio.  What you have to do is set AUDC0 to $1x or some other odd value.  Normally this plays no sound, but it pops the speaker.  By varying the volume, you can play a 4-bit quality audio sample, with the disadvantage that it will of course take up the entire CPU time for the duration of the sound being played.  I will attempt to work up a test example to see if it will work in the emulator or not.

Butwait... if the POKEY is like the TIA, you can set all 4 channels to 1x and play 4 4 bit samples at once or 1 6 bit sample! Almost as good as NES.

[Ecernosoft]

I already did something like this to play 16KHZ samples on the TIA, here's a link: 

 

[Ecernosoft]

On 4/22/2022 at 2:04 PM, Synthpopalooza said:

So, further testing and A7800 is about 98% to 99% good to real hardware.

 

I am putting efforts now (in addition to documenting new POKEY settings) to Dragonfly stereo POKEY.  I know actual emulation is a ways away for this, but I am going to work up actual examples anyway towards that eventuality.  It'll be a rendition of music from Metroid. 

 

I do need a reminder tho ... how do I edit the .128 file to make a binary addressable by the Dragonfly, for $440 and $450 POKEY?  I've got the music player code right, I'm certain ...

You're breaking my mind..... Arrgh!

You can look at the old world .a78 header documentation if that helps.

Edited August 12, 2022 by Ecernosoft

[SlidellMan]

Will your pokey Dragonfly settings be compatible with Raster Music Tracker songs that use Stereo?

[Synthpopalooza]

I think so.  The two POKEY have to be mapped at $440 and $450, and some jiggerypokery has to be done with the .a78 header 

[+-^CrossBow^-]

2 minutes ago, Synthpopalooza said:

I think so.  The two POKEY have to be mapped at $440 and $450, and some jiggerypokery has to be done with the .a78 header 

To say nothing of the modifications needed on the DF to make it work since both Pokeys are combined just before going into the cartridge port. I know a 3.5mm jack could be added to break this out, but then you need an external mixer to mix your TIA + Pokey and then back to your receiver/TV to get the right balance with all the stereo channels in place right?

[Synthpopalooza]

Yes.  DF mixes it into mono.  Which has never been an issue with me because my double POKEY music is designed for mono.