GTIA music

[xxl]

Bon Appetit

sinclairswing.xex

Edited February 23, 2018 by xxl

[Geister]

What does it mean GTIA music? Do you mean Pokey music? What do you do with the XEX file? It doesn't seem to load on Altirra.

[Panther]

I got it to work on Altirra, but had to disable the U1MB.

[ndary]

Very impressive, hard to believe the GTIA can generate such quality music by itself.

 

Nir

[emkay]

What does it mean GTIA music? Do you mean Pokey music? What do you do with the XEX file? It doesn't seem to load on Altirra.

GTIA is "somehow" the real soundchip in the Atari. The "TIA" in the 2600 system had real features for that.

In the Atari, it only has a single pulse to offer after a write to the register. Regulary used for the key-click in the Atari, it can be used to create digitized sounds. Which means , at the end, it's not GTIA music but CPU music played through the GTIA.

[Heaven/TQA]

actually its not GTIA "playing" music ... as emkay said... it's CPU driven sampling generating waves while GTIA "outputs" the sound... could be POKEY volume regs too... or ZX spectrum, c64 or whatever has a volume bit

Edited February 24, 2018 by Heaven/TQA

[emkay]

And I'm quite curious of a POKEY player that uses all 4 channels for digi replay and shifted timings to fade the high sampling noise.

[Mclaneinc]

That is kind of freaky but also impressive...Put altirra's audio monitor on and indeed saw no pokey use...Really weird and nice...

[Keatah]

This is like that Sci-Fi alternate universe stuff. Graphics chips making sound..PPPFFAAgggghhhhh!!

[xxl]

in that case, try a bit of madness

 

 

 

storm.xex

[Gunstar]

There has been other GTIA tunes out for years, maybe even decades, nothing new here as far as that goes. I've been saying since the 80's that games should use both Pokey and GTIA so you can have 4-channel Pokey tunes in-game and have the GTIA doing sounds, or vice-versa, whatever. No need to have to choose between sound and music in games.

 

Just like the TIA is responsible for sound and music in the 2600 and most 7800 games, the GTIA is a third generation TIA (CTIA was 2nd). Why more people aren't aware of this after so many decades is beyond me...

Edited February 24, 2018 by Gunstar

[xxl]

could you give the title? I will be happy to hear how it was done

[_The Doctor__]

Nope, not that crazy for sound at all, keyboard chips, graphics chips, they are all in another dimension in the Atari, a parallel dimension if you will... you should expect the unusual from these fine machines..

 

he may be referring to what some started calling 'beeper' music...

Edited February 25, 2018 by _The Doctor__

[Keatah]

In the Apple II we made a 100 baud modem with the cassette port back in the day. Today, through software, the tape port can accept data at 20,000 baud. And the serial port 115,200 baud. Then there is a "big mod" for the Disk II that can draw a graphical image of the exact bits and flux transitions. Next I expect to see two Apple II units, each having their composite video out connected to a stereo amplifier L/R inputs. And the game ports connected to each other for sync. And out comes CD quality music. Or some shit like that.

[Gunstar]

could you give the title? I will be happy to hear how it was done

if you are referring to my post, I don't recall any "tune" in particular, I'll have a look through my thousands of files and see if I can stumble upon some GTIA music previously released. But I'm also referring to stuff you yourself have done in the past too, XXL. Off the top of my head, the Beap them all 1 and 2 music releases.

Edited February 25, 2018 by Gunstar

[+Nezgar]

So, this should play out of the internal speaker in a real Atari 800, like the key-click sound does. Anyone have one to try it on?

 

I also remember Whomper Stomper would play its digitized voice out of the internal 800 speaker.

Edited February 25, 2018 by Nezgar

[+Nezgar]

And I'm quite curious of a POKEY player that uses all 4 channels for digi replay and shifted timings to fade the high sampling noise.

 

There's an interesting idea... In theory, analog mixing of 4 x 4-bit amplitude mode channels should yield the equivalent of 6-bit (64 amplitudes instead of 16)

 

The CPU overhead required to keep the sample rate high enough and the channel amplitude changes synced would probably keep this unfeasible for stock 1.79Mhz CPU's. Maybe if driven by an accelerated CPU.

[phaeron]

So, this should play out of the internal speaker in a real Atari 800, like the key-click sound does. Anyone have one to try it on?

 

Doesn't work since it tries to use memory under the OS ROM -- makes sounds like a power washer instead of music.

[+Nezgar]

 

Doesn't work since it tries to use memory under the OS ROM -- makes sounds like a power washer instead of music.

 

Darn! I found pressing any key restarts the song. Holding a key produces a sound similar to your description. Maybe with the 800 OS it thinks a key is pressed? Or the catch-all error trap behaviour is the same...

Edited February 25, 2018 by Nezgar

[Keatah]

I couldn't get the 400/800 to work, but the next models up did..

[+Nezgar]

xxl posted this other demo way back in 2008

http://atariage.com/forums/topic/134825-gtia-soundcard/?p=1624128

Maybe this runs on an 800

[Keatah]

It does. At least in emulation.

 

So, these things are called Beep tunes or Beep music.. It's amazing how identical to the Apple II they sound like. Any sound made by the II has to be made like this. The Apple II has no synthesis chip, and all it can do is push the speaker cone out in little ticks via a transistor and TTL chip.

[Heaven/TQA]

They sound identical because PWM tech is same.

[Keatah]

It's amazing. Yet it isn't. Some of the early action games on the Apple II eventually got ported to the Atari and they sounded identical. I swear you could hook a scope up and count the cycles. Exactly. The boops and ticks and plops..not forgetting the beeps! I guess I'm surprised it comes from the GTIA. That's all.

 

How and to what is the Atari internal speaker hooked up?

[emkay]

There's an interesting idea... In theory, analog mixing of 4 x 4-bit amplitude mode channels should yield the equivalent of 6-bit (64 amplitudes instead of 16)

 

The CPU overhead required to keep the sample rate high enough and the channel amplitude changes synced would probably keep this unfeasible for stock 1.79Mhz CPU's. Maybe if driven by an accelerated CPU.

 

?

 

Softsynth runs a 3kHz and sounds valid . The idea is to have lower sampling rates and to put the sampling noise to a unhearable high frequency. Just play the same sample value through all 4 channels and give the channels an offset , till the low tones add together .