Ti 99/4a sound chip

[HOME AUTOMATION]

5 hours ago, Jamesapp said:

i wouldnt mind that book

SN76489.pdf

 

SN76494.pdf

 

https://www.smspower.org/Development/SN76489?

 

http://www.zeridajh.org/articles/me_sn76489_sound_chip_details

[Casey]

57 minutes ago, OLD CS1 said:

In XB:

 

CALL SOUND(4250,220,15)::CALL SAY("HELLO THERE")

 

I actually wasn't sure - I don't have my TI handy at the moment so I could not try it.  Which is all to say, I'm not sure what caused this:

 

2 hours ago, Jamesapp said:

Just wrote a small program with basic sound and call say with the speech synthesizer

 

made me think maybe i really cant do what im trying to do? Because the synthesizer plays when the audio is stopped and vice versa where its not really mixing. Again it might be partly how im thinking but dont know. The level sounds good but its not playing at the same time? 
 

but im gonna keep at it?

 

[Casey]

(delete - duplicate)

Edited September 20, 2022 by Casey

[Jamesapp]

Hello

 

just did this in extended basic sounds good for my needs. i.e a good mix

 

So potentially i can fool around with doing some mixing on the ti sound chip. 
 

can anyone help me to understand what i said about the program? I was reading i think pin 4 is the audio gate. But i wondered if it will allow me to use the white plug as a lind in? 
 

and i do know ordinarily headphone out on digital recorder would be used with the white wire. 
 

also that the program wont adjust levels. 
 

but will it let me use the din cassette socket and the white cable as a line in?

 

can someone explain that to me? 

[JB]

1 hour ago, Jamesapp said:

so it wouldnt have to adjust levels but allow me to use the cable differently to act as an audio line in so i could use on my digital recorder as a left right audio line out? 
 

still not sure if this? 

No. The circuit in the TI for the cassette port expects speaker-level signals, not line-level signals.

 

If you remember PC soundcards, and how some had a speaker out and didn't need powered speakers, while others had a line out and required powered speakers?

The same concept applies here. If a port says "line out", it is not powerful enough to make it through the path between the TI's cassette port and final audio output.

[Jamesapp]

20 minutes ago, JB said:

No. The circuit in the TI for the cassette port expects speaker-level signals, not line-level signals.

 

If you remember PC soundcards, and how some had a speaker out and didn't need powered speakers, while others had a line out and required powered speakers?

The same concept applies here. If a port says "line out", it is not powerful enough to make it through the path between the TI's cassette port and final audio output.

Hello

 

thanks. 
 

ok so if that is the case. 
 

could i possible meake a custom din pin using pin 4? To get to the audio gate pin?
 

Is that possible or would i still be using headphone out with that? 
 

i really want line level input into the sound chip. 
 

would that be possible or should i forget about the din socket? 
 

Thats my next question? 
 

i really feel stupid asking all these questions, but im new to this? 

[RickyDean]

 

3 hours ago, Jamesapp said:

Hello

 

thanks. 
 

ok so if that is the case. 
 

could i possible meake a custom din pin using pin 4? To get to the audio gate pin?
 

Is that possible or would i still be using headphone out with that? 
 

i really want line level input into the sound chip. 
 

would that be possible or should i forget about the din socket? 
 

Thats my next question? 
 

i really feel stupid asking all these questions, but im new to this? 

Don't feel stupid, you're just attempting something that most haven't tried to do, due to the nature of the TI. More power to you, if you can accomplish what your trying to do here

[Jamesapp]

10 hours ago, JB said:

No. The circuit in the TI for the cassette port expects speaker-level signals, not line-level signals.

 

If you remember PC soundcards, and how some had a speaker out and didn't need powered speakers, while others had a line out and required powered speakers?

The same concept applies here. If a port says "line out", it is not powerful enough to make it through the path between the TI's cassette port and final audio output.

Ok thanks

 

ok so for what im trying to do would it be theroretically possible to make a din cable for my purposes? I mean when i read some documentation is it pin 4. As far as i know that is not used in the cassette cable. 
 

i would try to wire pin 4. 
 

or would i be better off using the side port which someone mentioned earlier that uses the speech synthesizer? 
 

 

[Jamesapp]

One thing i just thought of the thread overall. 
 

my views. Is that the sound chip in my ti 99/4a does have an audio line in port. 
 

from what ive heard through the speech synthesizer it sounded good. 
 

but it seems like ive been trying to use the cassette headphone jack. Which i was just thinking was designed to recieve audio from the cassette for saving loading files. 
 

i think i got obseessed with using this to mix audio to the chip.

 

but the way i feel is that the sound chip has an audio in port. That conceivably i could send a line level out from another source like my digital recorder to fool around with 8 bit music?

 

now how good this will be technically level balance etc. i dont know yet. Maybe if i do get there i wont like the results? 
 

but my speech synthesizer sounds good to me subjectively. I wrote a small program last night in extended basic which combined the speech synthesizer and a small basic 8 bit music thing. 
 

and as far as level balance a basic mix is what i want to do. 
 

i do have hopes for the program written earlier. Because from my understanding the audio in on the chip is different than the audio headphone from the cassette. 
 

ive given up on the idea of using the casseette cable. 
 

my thought now are trying 3. Things:

 

trying to build or find a custom din pin to hook up to the cassette port? But wired different do i would load thd program from earlier. I get mixed up but wire it to the audio gate pin is it pin 4. Ive never heard that term audio gate before. That seems like what i want. I want to open the gate on thd chip and send it line level audio. 
 

i wonder if they have a kit with a generic din cable that you can kind of customize? 
 

2. going in through the speech synthesizer port? 
 

3. Have my ti modded to have a permanent audio line in for chiptune music.

Edited September 20, 2022 by Jamesapp

[+mizapf]

I don't know how well you are familiar with schematics; here is the part with Audio Gate. The "Audio Gate" is a certain line on the circuit on the left (P8) which, when set to 0, makes the transistor Q400 (down on the right) block, and thus directs the sound from the cassette input (MAG IN) via R404 and R405 to the Audio In pin of the sound chip. When set to 1, the transistor opens and pulls down the line, so you don't hear anything.

 

The only use case here is to make the cassette data audible on the speaker so you can check whether everything is properly set (quality, volume etc.).

 

Note that the sound chip itself has nothing to do with loading or saving cassette data. The circuitry you see here handles the cassette input/output. The sound chip's Audio In is only used to merge the incoming sound with the own generated sounds.

[+OLD CS1]

A quick interrogative: does the audio gate actually get used?  I cannot recall any time when the audio from the cassette port is not heard through the system.

[Asmusr]

I tried a few experiments with a little Casio keyboard, a jack to jack cable in the headphone socket of the Casio, and two alligator clips. If I connected the tip of the jack plug at the other end of the cable to the white cassette cable and the sleeve to the red cassette cable (tip or sleeve on the cassette cable didn't matter), I could hear the output from the Casio faintly on my TI. If I connected the tip directly to pin 4 on the cassette port and the sleeve to pin 5, I could hear the output very well. No specific software on the TI was required to hear the output. Connecting only to the white cable didn't work. 

So yes, it should be possible to build a special cable to connect the Casio directly to the joystick port. You need a 9 pin d-sub plug, a jack cable where you cut off one end, and a soldering iron. 

[Jamesapp]

4 hours ago, mizapf said:

I don't know how well you are familiar with schematics; here is the part with Audio Gate. The "Audio Gate" is a certain line on the circuit on the left (P8) which, when set to 0, makes the transistor Q400 (down on the right) block, and thus directs the sound from the cassette input (MAG IN) via R404 and R405 to the Audio In pin of the sound chip. When set to 1, the transistor opens and pulls down the line, so you don't hear anything.

 

The only use case here is to make the cassette data audible on the speaker so you can check whether everything is properly set (quality, volume etc.).

 

Note that the sound chip itself has nothing to do with loading or saving cassette data. The circuitry you see here handles the cassette input/output. The sound chip's Audio In is only used to merge the incoming sound with the own generated sounds.

So are you saying that there is no point in using pin 4 or pin 8 for what im trying to do? 
 

in other words lets say i went ahead and made a custom din plug and used that to go from my audio line out of my digitsl recorder. Id bassicslly get the same thing audio wise weather i run the program or not? 
 

and when you say audio line in is only used for mixing thd sound coming from the cassette? For that circuitry right? 
 

what about the speech synthesizer its use in the sound chip im happy with. Dosent it also use the audio in port?

 

also am i thinking of this wrong, i.e. the cassette cable is expecting certain sound level wise coming from the headphones. 
 

is there a practical way of sending line level audio to the sound chip audio in? 
 

im trying to figure this out. Im thinking i dont want anything to do with the cassette cable. 
 

but is the audio in on the chip tiied to the cassette headphone curcuitry. What about the speech synthesizer? 
 

im thinking that audio from the synethizer wouldnt be like headphone level right? 
 

i wrote a small program and played speech and 8 bit music together. And i was very happy with the mix.

 

id like to do something similiar with an analog audio coming from a line out? Like either my digital recorder or a casitone keyboard? 
 

not to confuse things but someday i want to send 8 biy t audio from another chip too and fool around with another voice. I just bought 4 ay-3-8910 chips. 
 

im confused now. Can anyone tell me if i forget about the cassette and its circuitry and the program from earlier. 
 

Anything about the audio in on the sound chip? 
 

can it take a line level? That is my question now. 
 

i think someone mentioned that it could be the way the chip is set up is that the audio in i.e. the amp transistor i dont know what its called is designed to except audio from the cassette headphone port? 
 

i dont know anything but that doesent seem right? The speech synthesizer ive used had a great mix? Also this sound chip wasnt just used in the ti? 
 

but thats my main question at this point. Any info on the audio in on the sound chip? 
 

maybe i could research how the audio in was used in other devices like arcade games? 

[Jamesapp]

18 minutes ago, Asmusr said:

I tried a few experiments with a little Casio keyboard, a jack to jack cable in the headphone socket of the Casio, and two alligator clips. If I connected the tip of the jack plug at the other end of the cable to the white cassette cable and the sleeve to the red cassette cable (tip or sleeve on the cassette cable didn't matter), I could hear the output from the Casio faintly on my TI. If I connected the tip directly to pin 4 on the cassette port and the sleeve to pin 5, I could hear the output very well. No specific software on the TI was required to hear the output. Connecting only to the white cable didn't work. 

So yes, it should be possible to build a special cable to connect the Casio directly to the joystick port. You need a 9 pin d-sub plug, a jack cable where you cut off one end, and a soldering iron. 

Thank you for the info. 
 

 

[Jamesapp]

22 minutes ago, Asmusr said:

I tried a few experiments with a little Casio keyboard, a jack to jack cable in the headphone socket of the Casio, and two alligator clips. If I connected the tip of the jack plug at the other end of the cable to the white cassette cable and the sleeve to the red cassette cable (tip or sleeve on the cassette cable didn't matter), I could hear the output from the Casio faintly on my TI. If I connected the tip directly to pin 4 on the cassette port and the sleeve to pin 5, I could hear the output very well. No specific software on the TI was required to hear the output. Connecting only to the white cable didn't work. 

So yes, it should be possible to build a special cable to connect the Casio directly to the joystick port. You need a 9 pin d-sub plug, a jack cable where you cut off one end, and a soldering iron. 

Amsusr

 

just curious you used the headphone out on the casio? 
 

i guess if i get a good sound i dont care. 
 

and maybe it is built into the circutry of the cassette audio chip interface?

 

but i appreciate the info. Its a project i might tackle if i get what i need din plug etc. 

 

—————-/—————————————/

 

but im still curious about line level. I have negative conotations of headphone levels probally biassd just based on what ive read online and my sxperiments with the ti

 

————————————————

 

but if i get good sound i guess ig doesent matter. 
 

bug there has to be a way to send line level out to the chip?

lets say i get one of my ay-3-8920 working, im gonna get a kit with an arduino bread board etc.

 

bug lets say i got that working and i want to mix the signal with my ti 99/4a audio in on thd chip. That i would have to use headphone level, i couldnt use line level? 
 

thats what i really want to find out at this point. Can the sound chip in my ti 99/4a except audio line level signal or not? 
 

 

[Jamesapp]

Just found this on the chips. 
 

it says for audio in 0 to 1.8 mA

 

i don’t know anything about audio. Is this an acceptabld current for line level? 
 

again i dont know anything about sound circuitry? 
 

but here is a link talkkng about the chips.

 

http://www.vgmpf.com/Wiki/images/9/9c/SN76494_-_Manual.pdf

[+mizapf]

1 hour ago, Jamesapp said:

So are you saying that there is no point in using pin 4 or pin 8 for what im trying to do?

I cannot answer this question because I am still unsure what you're trying to achieve. I just explained what the audio gate is.

 

1 hour ago, Jamesapp said:

maybe i could research how the audio in was used in other devices like arcade games? 

There is a compatible sound chip without Audio In (SN76489AN). Arcade machines may make use of that chip, so you have to exactly check the type.

[+TheBF]

12 minutes ago, Jamesapp said:

Just found this on the chips. 
 

it says for audio in 0 to 1.8 mA

 

i don’t know anything about audio. Is this an acceptabld current for line level? 
 

again i dont know anything about sound circuitry? 
 

but here is a link talkkng about the chips.

 

http://www.vgmpf.com/Wiki/images/9/9c/SN76494_-_Manual.pdf

The relevant specs for audio levels are the input voltage.

Looks like that range is 2V to .8V  (hi and lo spec)

 

One the problems you will face is that "line level" has different meanings depending on where you are, who built the equiement and is it "home" equipment or "pro" equipment.

 

"Reference level of home line levels is typically -10 dBV, (.316 volts) peak signals are assumed to go 10 dB higher,  dBV or 1V.

 

So nominal line level of .3 volts might be on the low side for the TI.

 

The thing is this audio has literally nothing to do with the sound chip.  It is simply passed through the computer.  You would accomplish the same thing if you  mix the TI-99 and your external sound source in a small audio mixer. 

Not sure what you really are trying to do as the end goal.

 

[Jamesapp]

1 hour ago, TheBF said:

The relevant specs for audio levels are the input voltage.

Looks like that range is 2V to .8V  (hi and lo spec)

 

One the problems you will face is that "line level" has different meanings depending on where you are, who built the equiement and is it "home" equipment or "pro" equipment.

 

"Reference level of home line levels is typically -10 dBV, (.316 volts) peak signals are assumed to go 10 dB higher,  dBV or 1V.

 

So nominal line level of .3 volts might be on the low side for the TI.

 

The thing is this audio has literally nothing to do with the sound chip.  It is simply passed through the computer.  You would accomplish the same thing if you  mix the TI-99 and your external sound source in a small audio mixer. 

Not sure what you really are trying to do as the end goal.

 

How can you say the audio has nothing to do with the sound chip? i mean it gets mixed with the sound generators? Or thats what ive read. Someone described it as an overlay. But the chip has to take the incoming signal and mix it with the sound genearators tones.
 

i mean bassically in terms of mixing two sounds together which is what im trying to accomplish. But i want to mix on the chip itself. 
 

as to why. One thing id love to add an extra sound chip to add a voice and get into polyphony. 
 

i realise i could do it on lets say a digital recorder. 
 

i have a project im working somewhat related but i bought 4 ay-3-8910 chips

 

i would love lets say to have a device where i send audio from an ay-3-8910 chip into my ti to be mixed in the ti and come out my clmputer speakers

 

again i realize i could usd lets say my mixer

 

in a way im doing it just to do it. But have other ideas. 

again i want to ask lets take the ti out of the equation. Can this sound chip the SN76496, accept line level as a audio line in? 
 

line level meaning not headphone level? 
 

again lets say from another chip, midi device casio keyboard etc. 

 

it seems like it should 

 

but i dont know anything about audio signals. I am going to re-read some of the last posts. 
 

i cant see a chip manufacturer having audio in just for headphone levels? 
 

i mean i understand it i guess in thd ti because of the cassette? 
 

i hoping im not being a pain. 
 

i mean if someone told me definatively. The audio line in on the chip cannot accept line level for mixing 8 bit music. If there credible than i could move on

 

i dont know if im thinking of this wrong. It seems like the chip has audio line in but that either the ti isnt designed for it or there isnt  a practical way to get to it? 
 

or maybe the chip iregardless of the ti because of circuitry preamps transistors etc cant accept line input

 

im confused. Like i said i am going to re-read the last couple of posts. 
 

the Thebf you said .3v would be on the lowsidecfor the ti? 
 

again is that because of the circuitry how the computer is designed do you think? Is it low for other uses? 
 

like lets say i set up my arduino and the ay-3-8910

 

and hypothetically buy a sound chip like the one in my ti? And i sent it .3v from another chip into the audio in? 
 

im trying to understand this

 

again as far as what im trying to accomplish. I really dont know exactly. I got into 8 bit music i read on wikipedia the sound chip in my ti had an audio in and i got excited. 
 

but even early on i dont know how practical this is. 
 

In a way i figured i want to try it and go from there? I havent been able to do it yet. 
 

its a good question though

 

ive tried googling for any info on someone using the audio in with not a lot of luck

 

And i dont know if my whole concept ideas are off

 

I said it earlier in an almost philosophic sense i like the idea of the two sources being locked somehow

 

and i dont necessarily mean litterally 

 

one project i want to do is writer 8 bit music in basic to be played along side a program i got years ago that runs colors on the screen. But before i do it i want to run everything through my ti. Small crt, sound programming, random color pattern

 

then i would mix in another source of sound possible another chip my digital recorder midi device keyboard etc. 

 

this may sound ambitous but i was gonna try and learn about the remote function and have the basic program start my digital recorders play button. My digital recorder has a loop function and there is a jack for a clickable foot switch to essentislly press play. 
 

i didnt even want to mention the project because i didnt want to get off topic. 
 

and the project is just an idea. But for almost philoshophic reasons id want the ti to be connected to the recorder and ultimatly to have the sound mixed in thd ti. I was even thinking of things like 60 cycle hum with electric outlets. I was gonna have everything hooked up to a surge protector. But i think that is the best reason to give for what im trying to do. 
 

that project is an example but id like to mix in the ti. Maybe not forever or under all circumstances. But i cant really seem to find out if i can do if of not?

 

and again what about the speech synethizer thats line level right? And that goes to audio in on the chip? Or is it not line level? 
 

i know i was very happy subjectively with the mix when they played together 8 bit music and speech. Kind of what i want to do but with a different source

 

Edited September 20, 2022 by Jamesapp

[+FarmerPotato]

No, a LINE OUT will never work with the TI sound chip input. 
 

Get a source with a headphone jack. Any iPod, phone with analog jack, or cassette recorder. Even a PC with headphone jack.
 

Speech synth was never line level either. It’s  made to drive a speaker or headphone. 

[+TheBF]

1 hour ago, Jamesapp said:

How can you say the audio has nothing to do with the sound chip? i mean it gets mixed with the sound generators? Or thats what ive read.

What I mean is that the audio input is an analog signal mixed (as analog) with the output of the digital sounds.

There is no digital involvement wth the chip and the analog audio.

It is an audio mix. That is very specific to an audio guy like me but may not mean much if you are new to audio.

 

 

[Jamesapp]

53 minutes ago, TheBF said:

What I mean is that the audio input is an analog signal mixed (as analog) with the output of the digital sounds.

There is no digital involvement wth the chip and the analog audio.

It is an audio mix. That is very specific to an audio guy like me but may not mean much if you are new to audio.

 

 

Ok

new to a log of the concepts. 
 

a related question analog vs digital audio. 
 

i wondered if i use another chip written with music in some varient of basic that would be considered analog still? 
 

anyway i do appreciate the help
 

 

[Jamesapp]

1 hour ago, TheBF said:

What I mean is that the audio input is an analog signal mixed (as analog) with the output of the digital sounds.

There is no digital involvement wth the chip and the analog audio.

It is an audio mix. That is very specific to an audio guy like me but may not mean much if you are new to audio.

 

 

Would you consider the speech synthesizer analog? 
 

and what about using the port the side port for sending line out audio from my digital recorder?

[HOME AUTOMATION]

4 hours ago, Jamesapp said:

But for almost philoshophic reasons id want the ti to be connected to the recorder and ultimatly to have the sound mixed in thd ti. I was even thinking of things like 60 cycle hum with electric outlets. I was gonna have everything hooked up to a surge protector. But i think that is the best reason to give for what im trying to do. 

The TI's, audio output is notorious for its LOW signal-to-noise ratio. So, if you like noise, your on the right track!

 

2 hours ago, Jamesapp said:

Would you consider the speech synthesizer analog? 

The SSS's, output is coming from a D/A converter ...if that helps. 

Edited September 21, 2022 by HOME AUTOMATION

[+TheBF]

2 hours ago, Jamesapp said:

Ok

new to a log of the concepts. 
 

a related question analog vs digital audio. 
 

i wondered if i use another chip written with music in some varient of basic that would be considered analog still? 
 

anyway i do appreciate the help
 

 

If you have never worked through details of digital sound and analog sound this is no doubt confusing.

 

The 9919 sound chip is a digital sound generator, in fact is 4 digital sound generators.

The output from the chip that goes to a loudspeaker is however analog audio.

Digital tech. is used to generate analog sound.

 

If you used another chip and programmed it with any computer language it would also use digital tech. to generate analog audio.

 

Why do we do that? Because human hearing requires analog audio in the form of sound waves.

 

If all this is like magic to you at the moment then i would recommend first studying how analog audio circuits, microphones, loudspeakers actually work.

Armed with that you can dive into digital recording to understand how sound is encoded as numbers/digits and becomes "digital" sound. 

Then how digital signals are decoded back to create analog signals to drive loudspeakers and ear pieces etc.   

Only then will this actually make sense even if you just get familiar with the high level concepts.