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AY-3-891x, YM2149, and POKEY synths


AndrewMartens
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Hi there, I'm Andrew Martens, the guy who worked on the SIDgroove project (referenced by TK on his Midibox SID project).  Ironically I never finished it, and I'm going to be ordering some MBHP_CORE and _SID boards so that I'll finally have a working SID synth.  :)

Anyways, that's besides the point.

The other day I ordered a few other old synth chips:  an AY-3-8914 (compatible with the AY-3-8910 and -8912), a YM2149F (pin compatible with the above, but apparently the registers are swapped around), and a pair of Atari POKEY ICs.  At first glance, it appears that I should be able to leverage the core module and MIOS in order to start off with a working hardware & software platform to make an add-on board for.

Is there anyone out here who might be interested in something like this?  Please note that if I do get around to making this work, I will definitely provide TK with schematics and code for this so that he can develop something better with it.  ;D

I'm not sure if I'll start on the 891x board or the POKEY board first, but I'll keep you posted.

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Guest Vercengetorex

Yes! Sounds like a great project!!

I would start with the atari module... bet there are plenty of cats around here that would be quite interested in a MIDIBox Atari-synth.

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The arcade game collectors I used to hang around with were buying Ballblazer game carts for the Atari 7800 because they have a Pokey chip inside.

Atari apparently dumped loads of these carts off on the discount retailers and surplus companies here in the US due to the lack of sales on the 7800.  No idea how many made it overseas.  A quick evilbay search shows a few for sale there (way cheaper than shipping a 1541 disk drive just to get a sound chip!)

Pokeys are rumored to be all of the "super game" 7800 carts, but I don't know if this is true.

For a quick overview of the Yamaha chips used in some of the common machines see Yamaha sound generators of the 1980s home computers

Best!

Smash

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always interested in new things... keep us informed!! the AY-3-8914 and YM2149F are sound chips for old (game)computers (intellivision)?! ;D

The AY-3-8914 is from the Intellivision, and the YM2149F is from the Atari ST.  POKEY chips were found in a number of Ataris (5200 and 7800 consoles and the 400 and 800 computers, I think).

I looked at the Midibox SID code last night:  most of it should be re-usable, at least to make a basic working system with these chips.  I don't have any experience writing demo music / chiptunes, so I don't really know what features musicians will need in the software in order to create cool patches.

That's getting ahead of myself, though.  Once my MBHP boards get shipped from SmashTV (after they're back in stock, of course), then I'll focus on this a bit more.  I'm going to steal the MBHP interface and output amplifier circuit from the SID module, and that should really take care of the hardware side of things.

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and the YM2149F is from the Atari ST.

OOokay ;)

Well now, I'm going to split my ST in pieces, anyway (needing one of those MC6850's).

One thing kept me from checking what sound chip it uses, was that I thought, that those aren't particularly interesting, just limited  - In musical terms. Just that old "bleepy stuff".

So making "bleepy stuff" interesting I suggest that you check out wavetable implementation from MB_SID. Using wavetables would allow "hammering those registers" - making very fast pitch changes ect.

So count me in the list of people interested.

Bye, Moebius

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Hi Andrew,

looking forward for your synth! Time to search for old Atari STs on Ebay before the prices rocket upwards! :-)

Btw.: my next synth will be based on the YMF262/YAC512, also known as OPL3 (-> MIDIbox FM). Seems that a whole synth family based on nostalcic sound chips comes up

Best Regards, Thorsten.

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Btw.: my next synth will be based on the YMF262/YAC512, also known as OPL3 (-> MIDIbox FM). Seems that a whole synth family based on nostalcic sound chips comes up

Ahh, excellent!  I'll have to look around and see if I can find any of those somewhere.  I've been meaning to experiment with FM synthesis but never found a convenient source of ICs to use.  Maybe I'll have to dig up some old ISA soundcards from somewhere...

I'll have to see if I can get my "MidiBox YM2149" working before your Midibox FM  ;)  Not sure where you find the time to work on all this, though!

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One thing kept me from checking what sound chip it uses, was that I thought, that those aren't particularly interesting, just limited  - In musical terms. Just that old "bleepy stuff".

i'm no expert on sound-ic's moebius, but ic's with that old bleepy stuff can have quite some good musical applications (ok, depends on your definition of music ;D)

Do you know of the Blacet Dark Star Chaos, it uses the sound ic (SN76477N, very rare/expensive now) used in old space invaders arcades. It's a noise-machine/filter, but the sound is good....! (i want that chip soooo bad)

cheers,

marcel

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y'know... i think i have a couple of these old chips....

i have so much junk here from the '70s - '80s.  found a bunch of old SBs, pro audio spectrums, adlib boards, and even a coupla those old TI 76477 chips in one of my junk piles.

beginning to wonder if my 'SoftMoogModular' should turn into something containing these chips and completely obviate the computer/softsynth model.

hmmmm,  .... grrrrrrrr.... you guys make me think toooo much!

:)

gb

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Do you know of the Blacet Dark Star Chaos, it uses the sound ic (SN76477N, very rare/expensive now)

You seem to miss a point here. SN76477 is a self contained (mostly) analog sound FX chip. It's functions are controlled by a simple external circuitry. Different breed altogether.

On the other hand, these old computer sound IC's need to be programmed, by pushing data to control registers. It's rather easy (?) to get those play notes. But just playing squarewaves, even with three note polyphony with envelopes, isn't really exciting.. But when those were programmed in computer games, the music programmer had his limited share of computer memory and cpu time. They used different tricks to make music as exciting as they could with these limited resources. Fast frequency modulations (Those SID trills/ arpeggios ;)), switching noise on/off (special fx, snare, hihat sounds) ect.

SO, implementing a synth based on these limited resources, is even more difficult. Comp. music programmers had free hands to do whatever they could - building a synth, programmer must think - What should the user be able to do with the chip.

---

gbert:

beginning to wonder if my 'SoftMoogModular' should turn into something containing these chips and completely obviate the computer/softsynth model.

Yes ;) (Just kiddin', really)

Well, a control surface for softsynth's is really an improvement from typical point and click approach. I was excited at VSTi's for a moment, but then I realised, that I'm starting to follow certain patterns working with them. (And the sound - Well, If everybody sounded same ;))

Bye, Moebius

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yeah, sid is the way to go if i build a hardware synth controlled by midibox knobs... not a bad idea.

right now i'm working on the second core for my control surface for moog modular (have you seen that?)

http://www.ggbnet.com/midibox.html

tho'  multiple opl3's from the proaudio spectrum,etc.  might be another alternative to SID, i am kinda looking into that now. (one of the 9000000 synth projects i have going on)

wonder if i should simply connect a core to the edge connectors on an SB Audigy? not as fast a pc interface but all the windoze overhead would be gone. that might be a project for JAL though instead of MIOS.

:)

c ya

gb

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You seem to miss a point here. SN76477 is a self contained (mostly) analog sound FX chip. It's functions are controlled by a simple external circuitry. Different breed altogether.

like i said i'm no expert , i was only thinking: vintage game sound ic, yeah!  

but thanks for clearing things up for me  ;)!

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like i said i'm no expert

I'm neither ;) Just slowly absorbing information and concepts from synth DIY field... aah, feed my brain... ;)

Bye, Moebius

p.s. gbeth: Yes I've seen that. Now I started to think. Why don't you pioneer MB64+AOUT+SHX8 based control of a voltage controlled modules?! I'm more or less aiming at that direction.. I'm also interested in your experiences with PAiA Fatman ;)

p.p.s. A nice information source for AY-3-891*: http://andercheran.aiind.upv.es/~amstrad/docs/ay38912/psgspec.htm

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hee hee hee hee... moebius, i've been working on that with and without midibox for about 3 years now.

actually have some working stuff with

pic (16f877 and 18f452) / ainx16 (kinda TK design but using 4067's instead of 4051's) / hacked multi paia FatMan based D2A's / JAL as a programming environment .  still using V/Hz  voltage controll hardware... next comes V/Oct.. in a few months.

anyway.... i'd like to swap knowledge bases with you on this subject!

gb

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p.p.s. A nice information source for AY-3-891*: http://andercheran.aiind.upv.es/~amstrad/docs/ay38912/psgspec.htm

I've got a pretty good set of datasheets for the new chips that I ordered.  Mostly what I need to figure out is how those demo coders did what they did with the chip - so far it appears to be wavetable / arpeggiated chord stuff which has been implemented for the SID already.  I think it was on the Atari ST where they took advantage of a 50 Hz interrupt to modify the parameters of the YM2149 - once I have basic sound working, I'll probably start in on that angle.  

Maybe faster modulation, though - hadn't TK said somewhere that we can modify at 1120 Hz?  Just a wee smidge faster than 50 Hz :)

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I've got a pretty good set of datasheets for the new chips that I ordered.
OK, I was impressed by the block diagram at the link i posted.

Maybe faster modulation, though - hadn't TK said somewhere that we can modify at 1120 Hz?  Just a wee smidge faster than 50 Hz :)

Yes. Registers on sid are updated with rate of that 1120Hz ;)

So you could try MidiboxSID application as a basis of your project. Of course adaptation is a hard work, but at least you have some code to be recycled ;)

Bye, Moebius

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  • 4 months later...

this thread was pretty quiet for some months ... Andrew are you still working on the pokey?

just interested .... my sid is just ready and i'm going to etch some cores intended for the seq2, MBFM, and 2 of my own pure midi app projects...

would be really cool to have another unique sound machine!!!

Martin

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Still working, but as I've mentioned in a few other threads, I barely have time to think about such projects these days - my fiancee has me busy with home decorating / renovating / organizing projects, and there's a wedding coming up in May.  My SID is mostly complete - if I can find a weekend to finish it off and put it in a case, then I should be able to get on to breadboarding one of these designs and hooking it up to my spare CORE module.

I plan on making this work at some point, but it will probably be quite a while before I get anything going.

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  • 1 year later...

Hey there!

I'm really impressed with SID project, however, having owned ZX Spectrum back in the day, I was wondeing if anyone can do similar thing with AY-3-891x... I still have the chip laying around somewhere..

However, I'm not that much of electronics/midi guru to create such project myself..

So, no results so far?

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