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By Sander

Founder (1865)

Sander's picture

24-03-2014, 21:40

@Heitor: please send the Franky card to me if possible. Thank you for your explanation. I'll bury the axe.

About Franky: Franky is not the same as the playsoniq. Franky only hold the Sega VDP processor, which has a integrated Texas Instruments SN76489.

Since I already have the PCB's gathering dust, we are now prototyping to only build up the logic inside for audio support. This will save a lot of expensive video components (video memory, pal/ntsc encoder).

The result will go as our SuperSoniqs SN76489 audio module, which may go for much lower price than the Franky VDP price.

Electronic fans can expand this cartridge in the future to a full fledged Franky if they want.

By hbarcellos

Hero (628)

hbarcellos's picture

25-03-2014, 02:47

@Sander, sent you an email to the last address that I had, so, we can discuss the details about shipping it back.
@msx.org
Let me know if you're using a different one.

Good to know that you'll bury the axe, and, maybe in the future, reactivating my "alter-friend" account could be considered.

Rgds,
HB.

By hbarcellos

Hero (628)

hbarcellos's picture

18-05-2014, 00:30

gdx, check this video.
It's an early prototype of my PSG only SN76489 emulator for AY-3-8910

As I never had converted Gyruss, I did it just to test the new emulator:

http://www.youtube.com/watch?v=RjYcCODa8FU

At least, now, it's possible to listen something when you die.

*PS* It's 32k and it only uses the PSG.

By Grauw

Ascended (10004)

Grauw's picture

18-05-2014, 03:23

Sander wrote:

The result will go as our SuperSoniqs SN76489 audio module, which may go for much lower price than the Franky VDP price.

Count me in! Smile

PlaySoniq would be nice to have for the SID chip, but it’s quite expensive… And although Franky is affordable, I wouldn’t use the video bits so I’m definitely in the market for a cheaper audio-only version. Maybe without video components the audio signal will also not get interference from them…

Will you add an audio output? Also, possibly a crystal so that it is not affected by 7MHz?

By ARTRAG

Enlighted (6515)

ARTRAG's picture

18-05-2014, 10:45

Now I see why SCC can help in SN7689 emulation. This latter has 4 channels where the 4th is dedicated to noise with independent volume control.
AY8910 mixes it noise generator with one (or more) of the 3 tones, thus there is no independent volume control for noise and tones.
Using SCC for tones (even one channel would be sufficient), would allow the AY free for accurate noise emulation.

By hbarcellos

Hero (628)

hbarcellos's picture

18-05-2014, 13:26

Well, two points:
1) I still believe that, with further deep investigation on two chips, my version 3 of the SN emulator will be more accurate.
Today, I'm taking the channel with LOUDEST volume to use it mixed with channel. I ignore noise volume (as long as its louder than nothing) and use the original tone channel volume.
Maybe I can use the opposite approach, take the lowest tone, mute it and use noise real volume.
There are still some things to investigate. SN Chip has two different noise types: White and "Periodic". For each one of those, it has only "three fixed variations" of frequency OR a 4th where it takes its frequency from tone channel 3. I still need to investigate that to see if it mutes tone while using that. The documentation is not clear.

2) Using any other chip is for sure an advantage. I would use it as you suggested, but, as far as I noticed, I think GDX version (he uses the sound from mission if I'm correct) even with SCC, don't emulate proper noise.
But, why not FM instead of SCC? I think FM chips are cheaper and easier to find than the SCC, right?
Would make it easier to create an FM cart

By Grauw

Ascended (10004)

Grauw's picture

18-05-2014, 13:54

Because SCC can reproduce a square wave while MSX-Music and MSX-Audio can only do sine waves.

By hbarcellos

Hero (628)

hbarcellos's picture

18-05-2014, 14:30

Well, I know, but, that would not open some other nice possibilities, like changing noise for a "drum" for instance?
I don't know too much about FM, but on AY/SN chips, if I set a tone frequency on channel A, it keeps playing until something is changed (like muting channel). On FM, I was told that it works more like a "piano", where you send a command to "press" the correct instrument key.
That means that the note will be played and then fade, leaving no sound after a while, right?

If so, maybe it's really hard to transform from one side to the other...

By Grauw

Ascended (10004)

Grauw's picture

18-05-2014, 15:04

hbarcellos wrote:

I don't know too much about FM, but on AY/SN chips, if I set a tone frequency on channel A, it keeps playing until something is changed (like muting channel).

No that isn’t true, it depends on how you set the PSG’s envelope, right? On FM it’s the same, though the envelope generator offers different functionality. You can set it to sound continuously (e.g. flute sound).

By ericb59

Paragon (1046)

ericb59's picture

18-05-2014, 15:07

yes Fm chips are more easy to find.
why not using Ym2413 ?Fmpac is a very popular product, and is include in msx2+ and TR.
Perhaps you emulation don't have to be so accurate compare to the original...
perhaps it can be better when using a Ym2413 ... ?

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