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SID alternative for the TI99


Tuxon86
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Hi,

 

We know that there’s presently a card available that can interface a C64 Sid chip to the 99/4a, but has anybody given any thought in interfacing with a teensy coupled with the audio shield for it? You could the define multiple channel of audio with full ADSR control for way less money and trouble that sourcing a working Sid.

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The big advantage of the SID Master 99 is to take advantage of an existing library of music.  It can be used for other things, but is not.  We have discussed around here using other sound chips, like an AY or a POKEY.  The question that comes up in the conversations is, "why?"  It would be a niche product and require that something support it.  Even the FortTI (4x PSG) expansion supports existing software by sending the commands at the standard 9919 port to all four chips.  You cannot do that with anything else which adds a different sound chip, you would need software which specifically supports it.  But, if you build it, maybe they will come.

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To be attractive to me as developer, a new sound card should be backwards compatible with the standard sound chip and be simple enough for emulators to support it.

 

To be attractive to me as user, a new sound card should be able to enrich the sound of existing games by configuration only.

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11 hours ago, OLD CS1 said:

The big advantage of the SID Master 99 is to take advantage of an existing library of music.  It can be used for other things, but is not.  We have discussed around here using other sound chips, like an AY or a POKEY.  The question that comes up in the conversations is, "why?"  It would be a niche product and require that something support it.  Even the FortTI (4x PSG) expansion supports existing software by sending the commands at the standard 9919 port to all four chips.  You cannot do that with anything else which adds a different sound chip, you would need software which specifically supports it.  But, if you build it, maybe they will come.

Yes, make more ForTI music cards!

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1 hour ago, arcadeshopper said:

I've been poking the bears about this for the last year or two.. so far no boards :) 

@FarmerPotato @Ksarul

Please don't give up on your efforts.  I need just one TI sound chip to fix mine, but it can wait until I can set my PEB back up.  It's been down since we moved and I only have half the space I had before the move.  So a very slow process for me to do.

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4 hours ago, arcadeshopper said:

I've been poking the bears about this for the last year or two.. so far no boards :) 

@FarmerPotato @Ksarul

I have been sitting on a partial design for a ForTI which hangs off Matt's 32k, but I have had little time or motivation.  Honestly feel bad about it because of some of the help I have received.  Just having trouble finding joy these days.

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22 minutes ago, OLD CS1 said:

I have been sitting on a partial design for a ForTI which hangs off Matt's 32k, but I have had little time or motivation.  Honestly feel bad about it because of some of the help I have received.  Just having trouble finding joy these days.

that would be cool :)   hope it gets better man

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16 hours ago, Asmusr said:

To be attractive to me as developer, a new sound card should be backwards compatible with the standard sound chip and be simple enough for emulators to support it.

 

To be attractive to me as user, a new sound card should be able to enrich the sound of existing games by configuration only.

My idea of such a card would still leave the native sound available. The teensy can be used as a midi device and it has its own audio output. You could even patch the Ti audio and mix both signal. Heck, you could probably use it with a serial connection via the rs232 interface.

 

I’m suggesting it as an alternative to the use of expensive and getting hard to find SID chips. 
 

Here’s an exemple of a synth project using the teensy: 

 

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16 hours ago, Asmusr said:

To be attractive to me as developer, a new sound card should be backwards compatible with the standard sound chip and be simple enough for emulators to support it.

 

To be attractive to me as user, a new sound card should be able to enrich the sound of existing games by configuration only.

 

I've collected many of the 1980s Yamaha sound chips and some of them I really like.  I found oddball chips like the TI SN76477 and XR2206.   But I try to imagine things that work out of the box with the 4A, using 9919 byte commands.

 

Some ways to bridge that gap:

 

1. Multiple 9919 with extra stages added, such as mixing, or low-pass filter

2. EPROM translating all possible 9919 command bytes into other kind of chips' register writes. DSR ROM to initialize said chips. 

3. Alternate frequency generators; build up a 9919 compatible out of chips giving control over waveform, plus effects. 

 

 

I've imagined a range of ideas 

 

1. All digital solution, where 9919 commands trigger God-almighty amounts of synthesizer power.  I've lost interest in this.

 

2. Multiple 9919 sound chips (4 at least) with modifications.  For instance, analog mixing, analog effects, different clock rates per chip.  Add a digital-controlled low-pass-filter chip from TI. (like TLC04 for $2.62 -- made 1986-present)

 

3. Memory banks--waveforms--clocked out by a 9919 square wave (PLL clock multiplier needed). 

 

4. Other vintage chips, with a CPLD translator in between.  I like Yamaha OPNA (YM2608) and OPL3 (YMF262). Others prefer OPN2 (YM2612).  A DSR ROM to initialize voices, and some glue logic to translate each possible 9919 command sequence through a ROM into a series of alternate register writes. In this way, frequencies and attenuation are translated to an alien register set. (And the YMF262 way of tuning a frequency is... truly alien.) Advantage, there are large communities who developed for these chips (MSX, PC)

 

5. Other TI sound chips: SN76477 for instance is a weird one.  1978.  It's capable of good sound effects (I have many in my head), and what's never been exploited, frequency modulation feedback path. Truly oddball path. Search this forum, there's a band that features it.  This would be for the fun of it--needs no justification of compatibility.  No built-in digital interface!

 

6. Other other frequency generators.  For instance, a vintage Exar frequency generator XR2206 ($7) or sine or triangle wave.

 

7. Additional  TI audio codec.  I've been reading about the TLV320AIC3106 which costs about $3.  This is a 2006 product, still made, intended to play digital audio, but features an analog "matrix mixing" of 6 channels.  You may use or skip the A/D and D/A digital path.  If you use it, there are some neat filters you can configure. Simple effects include bass/midrange/treble adjustment. "3D" enhancement is described. Interface to its registers is by I2C or SPI which is quite doable with CRU instructions.  

 

8. Crazy amounts of TI DSP power with a TLV320AIC3254. (see also Application guide) $5, made since 2010. Not sure why the 3106 has the trademark "320" in its name (the TMS320 DSP was 40% of TI's revenue at one time.) But this is the real deal: you may load a program into a "MiniDSP" in the A/D or D/A stage to execute "1152 instructions on every audio sample at a 48kHz sample rate".

 

Why the TLV320 audio codecs? Because, well, it's still TI. 

 

Anyway, #2 is what I've built.  

 

I like the #7 path too, because it interfaces and mixes all analog lines with possible digital (I2S) streams, while adding a modest filter feature.

 

Would love to do #4 eventually. 

 

 

 

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Hi All, Currently waiting for parts, to build Peter Schubert's AT Music card (a ForTi type Clone) he designed in 1987, I have revamped it and added, 4 channel output and/or 2 stereo output plus 5 channel audio input. It fits on the RH port or can be stacked on top of another card(Peters mini cards) or it can be plugged into a MiniPEBox(new design), it is in phase one of testing etc, Let me know if you are interested, Regards Arto.

 

 

   

ATMusicCard1a.png

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3 hours ago, Artoj said:

Hi All, Currently waiting for parts, to build Peter Schubert's AT Music card (a ForTi type Clone) he designed in 1987, I have revamped it and added, 4 channel output and/or 2 stereo output plus 5 channel audio input. It fits on the RH port or can be stacked on top of another card(Peters mini cards) or it can be plugged into a MiniPEBox(new design), it is in phase one of testing etc, Let me know if you are interested, Regards Arto.

 

 

   

ATMusicCard1a.png

It sounds like a Blast (from the past)😊  Anyway, I'll have to wait and see once it's complete.  In the mean time I will just do my best to get my old TI PEB up and operational, so I can use my old TI ForTI card, but I'll keep watching this topic for your progress reports.

 

RetroBill (fdos)

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8 hours ago, Artoj said:

Hi All, Currently waiting for parts, to build Peter Schubert's AT Music card (a ForTi type Clone) he designed in 1987, I have revamped it and added, 4 channel output and/or 2 stereo output plus 5 channel audio input. It fits on the RH port or can be stacked on top of another card(Peters mini cards) or it can be plugged into a MiniPEBox(new design), it is in phase one of testing etc, Let me know if you are interested, Regards Arto.

 

 

   

ATMusicCard1a.png

Would like a pcb when you are ready

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1 hour ago, jrhodes said:

What ever the alternative ends up being, i hope it is just a matter of plugging it into the side port. I'd also settle for some sort of Raspberry-Pi hat/daughter board with a SID (real or simulated) that communicates back and forth with the TI via TIPI.

The Pi probably has the horsepower to run PlaySID.  Just need an audio output.

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48 minutes ago, OLD CS1 said:

The Pi probably has the horsepower to run PlaySID.  Just need an audio output.

The teensy is a glorified arduino and you can easily create a six voice ADSR synth with filter with its audio shield. The Pi could easily do this also.

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@arcadeshopper @Ksarul I'd also be interested in those prototype boards, please keep me posted when they're available.

 

On the topic of SID chips, there are things like the ARMSID which are plug in replacement for the SID chips. I wonder if anyone has tried those on the TI board?

On 12/4/2022 at 3:40 AM, FarmerPotato said:

Some ways to bridge that gap:

 

1. Multiple 9919 with extra stages added, such as mixing, or low-pass filter

2. EPROM translating all possible 9919 command bytes into other kind of chips' register writes. DSR ROM to initialize said chips. 

3. Alternate frequency generators; build up a 9919 compatible out of chips giving control over waveform, plus effects.

This is perhaps something similar I did a few years ago, with the ET-PEB board capturing writes to the TMS9919 chip and converting them to MIDI information in real time, as presented in this video. Now that I look at the video date it was four years ago... I still think it is very cool concept. I have acquired many more synths since then, perhaps I should revisit myself this project for fun :) , to the point of @Asmusr this approach is totally compatible with existing code, and you get whatever sounds you configure your synths to do. It could even be something based on a Teensy as @Tuxon86 was thinking.

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