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SOUND DIGITIZING

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SOUNDPORT.DSK

 

The above disk contains SOUNDPORT EXPERIMENT I for use with a Minimem and cassette recorder.

 

Files on the disk:

DATAFORCE - DF/80 for use with disk system - see page 7 of doc below

DISKTAPE - Allows you to make a tape copy of the file SOUNDPORT for use with Minimem.

DO_OLDCON,DO_OLDSND,DO_SAVECON,DO_SAVESND,DO_SNOOPER - These files were written by Doug Otten, former VAST member - See page 6.

PROGRAM0 - This is the original Console basic program put out by DATAFORCE.

PROGRAM1.PROGRAM2,PROGRAM3,PROGRAM4 - These were extracted from the above, see docs.

SOUNDPORT - Minimem program

 

SOUND PORT EXPERIMENT.pdf

 

 

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It would be neat if someone out there comes up with some cool audio for either one of these programs.

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Wow, there are so much stuff for digitizing.


I also know that there is also a program that digitize audio using TI99 and the tape Recorder, but still not found the floppy that containing it.


in the meantime, i found this package among my TI stuff instead:


i could scan and Dump it if not already done


post-24673-0-24803000-1550352027.jpg post-24673-0-56826100-1550352035.jpg



this was a short description of it, from Ernie Pegrem:

post-24673-0-15688600-1550352057_thumb.jpg

Edited by ti99iuc
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One wonders how that pio cable is configured. Could you whip up a schematic Ciro?

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One wonders how that pio cable is configured. Could you whip up a schematic Ciro?

 

well... i would like but the chip on the little PCB has text deleted, so i do not know how :(

 

post-24673-0-69909400-1550359120.jpg

Edited by ti99iuc

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well... i would like but the chip on the little PCB has text deleted, so i do not know how icon_sad.gif

 

attachicon.gif1.jpg

 

resistors in an array.. just take their value if you look at that link that Tursi provided it has this: lpt.jpg?w=620

 

all the chip is on the TI board is a bunch of resistors in a DIP package.

 

Greg

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Yep, exactly that!

 

I posted a pretty rough link, but a search for "LPT DAC" (LPT being the PC printer port, DAC being Digital-Analog Converter) brings up lots of schematics. Just remap the pins to the TI port and it will likely work fine. :)

 

Or just buy one of the still available PC remakes and use an adapter cable. :) They aren't intelligent so don't need any of the control lines.

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Didn't Perfect Push have digitized voice? So, no parallel weirdness...

Perfect Push utilized the sound chip output. It's possible to set the sound chip to the highest frequency and change the amplitude. There are 16 possible amplitude levels, and you can

process an 8-bit sample to a best fit, and play it back. It's not a tremendous fit, but it was pretty exciting to break through that limitation in 1986.

 

with the sound chip, you can do better by mixing 3 channels of that trick.

 

There is another trick I found on the Intellivision forum that rapidly changes the square wave frequency. They have decomposed the sample onto square wave basis functions, and select the 3 highest coefficients per playback sample period. Here is that thread: http://atariage.com/forums/topic/260647-sound-synthesis-with-square-waves/page-2?hl=fm%20synth

Sky Jaguar Speech 2 plays samples in game on 3 square waves. PSG is the AY-8910 chip.

This one I think requires an expansion hardware to add 5 SCC sine waves?

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Perfect Push utilized the sound chip output.

No, it didn't. ;) It did the title page speech by toggling the cassette audio gate line to provide a single-bit tick.

 

I released a TMNT game back in the day that played back audio through the sound chip - it was sampled from the cassette port so was still 1-bit:

 

 

There was a program called Sound F/X that also played back sampled audio, though it did use the full range. I don't see any samples of it on YouTube but it allowed you to load and play PC VOCs (and wavs?)

 

There is another trick I found on the Intellivision forum that rapidly changes the square wave frequency. They have decomposed the sample onto square wave basis functions, and select the 3 highest coefficients per playback sample period.

We also brought this one over to the TI, though the quality isn't quite there yet. (But at least one ColecoVision game used it). Sadly the extra range of the AY chip sound better than the TI PSG.

 

http://atariage.com/forums/topic/255859-voice-encoding-and-playback-with-no-speech-synth/?hl=%2Bartrag

 

I was working on porting it away from Matlab, but I need to get back to that. It's on my list. ;)

 

Of course my video playback plays back audio via the sound chip, with Dragon's Lair being the current best of my experiments there:

 

https://youtu.be/UXExQq0eq0Y?t=108

 

Now with all that time invested, my opinion is that it's hard to get much better quality. The sound chip is the slowest hardware in the console to write to (the speech synth is slower, but it's outside the console), which limits your maximum frequency. Worse than that, the logarithmic scale of the volume control means that there's very poor volume control for the louder sounds, all the fine detail is down at the softest end. Worse, although it's outside of the human hearing range, there's a high frequency square wave component which adds distortion to the audio.

 

All that to say - the 8-bit linear DAC on the parallel port would sound a lot better. ;) It'd be fun to do a video test to see what the quality difference sounds like...

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No, it didn't. ;) It did the title page speech by toggling the cassette audio gate line to provide a single-bit tick.

 

I released a TMNT game back in the day that played back audio through the sound chip - it was sampled from the cassette port so was still 1-bit:

Thanks for correcting me on that. I think I heard the Perfect Push sample on a disk with BUSHCNN and others for sound chip playback, so I thought it was done that way in the game.

Edited by FarmerPotato

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I'd like to just sit back and watch\listen this time...

If You and F.P. make it a contest...

...maybe I could sell tickets. :grin:

 

Good stuff.

 

I haven't touched it since 1987. I just found my disk though. It has some 8-bit samples I downloaded from CompuServe and converted to 4 bit without knowing that I should use a logarithmic scale. "My god its full of stars" and a TOS phaser sound. Barry Boone came up with the same technique, and published it, so I moved on.

 

I also had a program that would draw '*' when the cassette input was 1, and I experimented with filling the screen over and over just to see what patterns it might make. Totally ignorant about what to do next.

 

The real value to me? I spent a summer reading the E/A manual and asking myself 'what can I do with this info?' on every page. The world is so much more complicated today.

 

I don't want to get distracted by sound just when I've spent two weeks doing bitmap graphics routines.. I have a 24 bit I2S DAC hooked up to my 4A that I have to get back to... so many projects...

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Did the 8 bit samples you had use uLaw or ALaw type encoding? ( https://en.wikipedia.org/wiki/A-law_algorithm)

law is just a compression scheme to bring 12 and 13 bit down to 8 bit. Spent 11 years of my life living in that world. Despite the crazy math they use on Wikipedia in the real world it's just a lookup table. ;)

 

You can also just have pure 8 bit linear samples.

 

Thanks for correcting me on that. I think I heard the Perfect Push sample on a disk with BUSHCNN and others for sound chip playback, so I thought it was done that way in the game.

Curious about that disk! I only knew Perfect Push cause it was the only program I had with sampled speech back in the day, so when I implemented support in Classic99 to play back samples and it didn't work, I had to dig into it. ;)

 

I also had a program that would draw '*' when the cassette input was 1, and I experimented with filling the screen over and over just to see what patterns it might make.

Kind of curious about that, too, did you ever manage anything fun to see?

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law is just a compression scheme to bring 12 and 13 bit down to 8 bit. Spent 11 years of my life living in that world. Despite the crazy math they use on Wikipedia in the real world it's just a lookup table. ;)

 

You can also just have pure 8 bit linear samples.

 

I spent some time their too. One of our products was a test set for ISDN phones. Not a big market. :-D

My question was ill-stated. Has anyone used these compression techniques for 8 bit audio on the 99?

 

 

I can't think of a way to do the D/A conversion however so ignore me if this is irrelevant.

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I spent some time their too. One of our products was a test set for ISDN phones. Not a big market. :-D

My question was ill-stated. Has anyone used these compression techniques for 8 bit audio on the 99?

I can't think of a way to do the D/A conversion however so ignore me if this is irrelevant.

Unless you can play back samples with at least 12 bits of resolution, there's no value to using law compression. The TI totally can't as it stands. There are 4 bits of volume control on the sound chip. I don't think we'd get good results out of PWM on the sound chip, as I don't think we can hit it fast enough. A dedicated port might manage PWM, since we can go a lot faster without the delay, but if you're adding hardware anyway I'd just add a DAC, or dedicated sample-playback hardware.

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Not much of my old "Mike Ward" stuff has survived into the present day ;)

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