Duty Cycles Support

[emook]

What would the possibility be of supporting duty cycles on certain channels?

This sound was pioneered on the ST (artists list Scavenger etc) and has recently been realised on the ZX Spectrum.

[Targhan]

That’s what is called “[Atari ST] SID”. It *may* be implemented one day, but only when everything else is added. This is a tricky subject, because there are many ways of doing this, and many technical difficulties, especially on 8-bit machines (plus I admit I’m fond especially found of these sounds :)).
But if you go to the Atari ST player made by ggn, you will see that it has implemented SIDs in an “automated” way, so it might be interesting for you to check it out.

[e-dredon]

Hello.

I did a lot of research about that SID emulation in the last few weeks for the TNZS remake project. As far as I understood, the technology is based on interrupts and modifying “on the fly” the 14 8bit registers of the YM2149 and AY-3-8910/12 that are useful for the sound generators is quite tricky with the 8 bit machines based on 3-4Mhz Z80, as the duty cycles uses A LOT OF CPU.
This technology is in some way comparable to the split raster used by Roudou for the CRTC3 demo to get more colors displayed. TGS recently proved the SID is doable on the CPC+ with their demo Schnapps. https://www.youtube.com/watch?v=OMzC_ynbG-w (the credits part starts at 4:48). The DMA is probably massively used like with the Eerie forest demo. I think it would be a FANTASTIC addition to Arkos tracker and would open doors to a new generation of demos / games for the CPC+/spectrum next. The mod sampling trick used for the Eerie demo (Logon System) is great, but even heavily optimized, it needs 380KB of the 512kb limit of the cartdrige just for the intro song. I can’t go this way for TNZS (or perhaps for the main theme only as it’s just 45secs long).

Targhan: I was expecting your comment on the MIDI import thread 😉 the main song on the video I attached is just a subsong. I’m using the 58Hz at max playspeed so I get about 100ticks/second. On another subsong, I’m trying to play with Axx,Pxx effects and that #!!@!! super buggy buzzer to see if I can get a nice SID style LEAD played. Not much successful for now. I need a real CPC+ with my oscilloscope / signal analyzer for further experiments. 😉 I know Arkos Tracker is your own project, but maybe you could get in touch with Gilles Rimauro. He is working on a CPC+ soundtracker with the SID implementation and he’s aiming to get close to a zero nop used by the replay. https://www.facebook.com/gilles.rimauro

Cheers,

[Targhan]

I fully admit that SID is really not my cup of tea, and not in my TODO list right now… It simply takes too much CPU on machines without timer, and I don’t own a CPC+. I am fully aware of Zik’s Soundtrakker DMA, and maybe you can get in touch with him to get a working version. I also know how to implement it, but SID is much more than what you say, there are different versions of it (you can also play mini-samples, like I did in the intro of Imperial Mahjong).

Make a search on the CPC Wiki forum, BSC has released a few years ago a small WIP tracker that manages SID on CPC old. It is basic, but works. Also, Madram is soon going to release Ayane Lacarree, a CPC (old) software that will allow you to make SIDs. Of course, it will take all the CPU.

You could also compose your song with Maxymizer on Atari and export as YM, Offset has made a player that plays SID on CPC+.

My non-interest in SID is because:
– solutions exists, but NO ONE was ever interested in that on CPC, barely on CPC+.
– There are many effects that no one (but me?) use in their song, with a plain AY/YM. Who use hardware envelope with arpeggios, but example??
– This is up for debate, but I truly believe that the decline of quality of music on Atari ST started when SID appeared!! This is my opinion only :).

[emook]

Hi guys,

Just under 2 years ago I asked thiw question and was shown the source for the ST duty cycle verion.

Well I am glad to say we managed to eventually bringing this to the ZX Next.

Now we have ST and Next as targets is there now a new desired to add Atari-SID to the tracker?

We currently process regular PT3 files on the fly.

[emook]

Also clicking on “edit” post takes me to a completely different post so I cannot correct any errors! 🙂

[Targhan]

Yup, sorry about the Edit behavior, the forum plugin seems buggy…

Cool stuff about SID. This might be implemented one day… but it’s a heavy feature, there are so many things that can be done. Just checking at how the Maxymizer handles all that… The thing is that I’m not sure a lot of users would use such feature. On an 8 bit, it doesn’t sound very good in high frequencies, and it consumes 100% of the CPU. On Atari ST you have Maxymizer to produce SID music already, so…

But there WILL be a time when I think about it!!

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