AY-3-8910 Additional Waveforms

[NightSprinter]

Evening, David. First have to say I'm quite impressed with the potential with Chipsounds since I've began using it (haven't made music of my own yet). I'm curious about the implementation of the General Instruments AY-3-8910 sound chip (and its Yamaha equivalent). From games I've played in the past, it seems the chip is capable of more than just the listed square wave, three hard waves, and sync buzzer. I'll provide at least two examples.

In the arcade version of Gradius (which uses 2x AY chips), pulse-width control of the square waves and at least a sawtooth wave can be heard. Also, for the Intellivision game "Star Strike" when a player loses the game and a missile launches it sounds like a combination of a triangle wave and one of the hard waves the plugin does have.

I'm not sure how much this information for my request might help in improving the AY simulation, but hopefully the next version my info will help.

[davidv]

Hi

In the arcade version of Gradius (which uses 2x AY chips), pulse-width control of the square waves and at least a sawtooth wave can be heard.

Gradius also has two other chips:
1)Konami 005289 (a two channel 4bit wave table, like the GB), this is the first version of the Konami SCC (http://en.wikipedia.org/wiki/Konami_SCC)
(so the saw is most probably from there)
2)VLM5030 Speech synth.

Unless i hack in MAME a bit more and render each of the sound chip separately, its hard to know for sure. I however can render the AY portions of graduis separately on a REAL AY very easily (one after the other). I think ill try this later today

The PWM is doubtful since the chip does not provide this natively. MaxYMIser (http://www.preromanbritain.com/maxymiser/) does that with fast IRQ tricks, but that is a software mod that has native equivalent in other chips like the SID. Although to be frank I currently doubt the Gradius sound playback code implemented such tricks. Also sometimes what we hear as PWM is often phase tricks on two or more channels of pulse (as you noticed there would be 6 channels of pulse from the AYs in gradius)

Also, for the Intellivision game "Star Strike" when a player loses the game and a missile launches it sounds like a combination of a triangle wave and one of the hard waves the plugin does have.
I'm not sure how much this information for my request might help in improving the AY simulation, but hopefully the next version my info will help.

Other games, such as disk of tron also use the weird combination of Envelope+Noise+square. I'm already working on that see
http://ploguechipsounds.blogspot.com/20 ... otype.html

There are 2 mp3 examples of such waveform combination on that post, and also rationale why it didnt make chipsounds as is.

More AY talk in here:
http://www.plogue.com/phpBB2/viewtopic.php?t=4537
Kind regards!

[NightSprinter]

Yeah, I'm following on that. I see where you're getting at with the SCC chip (K005289) in Gradius. Coincidentally it's the exact same audio expansion chip that the VRC6 uses. If you would like such a chip to peruse, I can see what I can do to donate to this project.

So I think the closest I can get so far with the Bubble System sound would be to use the AY in combination with DMG instruments.

I'm also sending a PM to request the AY update.