Atari as a Synth / Sequencer

[Hornpipe2]

I've got a short stack of 8-bits in the garage and I need to turn them into something useful. "A-ha!" I thought. "I love the 8-bit sound. Let's make them into music tools!"

 

So who has advice on using the Atari 8-bits for music production and performance? Let's start with...

* model recommendations? (are some noisier or less stable? does extra RAM provide much benefit? etc)

* hardware and mods? I can add a mono audio-out jack easily. For stereo I've seen the standard piggyback mod which seems easiest, though I also know there are more advanced stereo out boards that do good things. What about MIDI control or...?

* software? I see lots of references to RMT on the forums which seems like a good choice for music tracker - are there other alternatives? Also something I haven't seen that I would like is a way to "play" the Atari as a keyboard synthesizer. Any tools like that exist?

 

-Greg

[analmux]

Well, listen for yourself:

 

http://www.phys.uu.nl/~bpos/IR/

 

Here you can download one of my Pokey chiptunes. This is possible with a standard mono Pokey chip on any 8bit having at least 16kb of RAM. It is not really CPU-intensive. It uses 10% of processing time, and makes no use of any sampling.

 

 

About your questions:

 

model recommendations? (are some noisier or less stable? does extra RAM provide much benefit?

 

I recommend the XL or XE series, as you also have GTIA sound mixed in (this is a 1-bit voice, only used for sampling). I never heard of any model being noisier or less stable than another model. Extra RAM will always help, especially when doing sampling. Pokey is suitable for 4bit DAC, and it supports exact timers causing an IRQ to run a software sound mode. So, sampling is easy. However, extra RAM is not really needed. Using a standard Atari 800XL, which has 64 kB of RAM, is enough for most purposes.

 

 

software? I see lots of references to RMT on the forums which seems like a good choice for music tracker

 

RMT is a great tool, but it doesn't run on the native machine. Only on a PC until now. However, I did a lot of research in sound/timbre/instrument possibilities of Pokey, but these aren't really supported by any tracker. That's why I wrote simple hacks of RMT to support some unusual instrumentation. The tune I linked to is one such an example. I wrote it using a hacked RMT, and mastered it using a bypass-hack afterwards. So, in standard RMT the above tune is impossible, or at least very difficult. Some of the new sounds suffer from non-exact emulation, so writing a songline with a certain instrument can have a different outcome on the real machine.

 

 

......I haven't seen that I would like is a way to "play" the Atari as a keyboard synthesizer. Any tools like that exist?

 

Well, there are some. Me myself wrote a simple keyboard sampler 10 years ago, but that one is quite simple, and it would need a good manual. Then one can use the upper & the lower part of the keyboard for 2 * 20 semitones. I used this program for a synth-jam evening at a pub in my parents town then.

 

Possibly you're interested in using MIDI-keyboards. This can be hard. A MIDI-keyboard works the best when using the serial ports of the Atari, however, the serial port is handled by the same Pokey chip, so it will use 1 or 2 of its Audio channels to support it. So, that leaves not much spare channels. However, writing a software driven MIDI-port, f.e. using one of the joystick-ports, should be an option, but this isn't designed yet as far as I'm correct. So, I wouldn't hope too much for this.

[Kernal]

Heres a simple synth proggie i created..

it only uses the number keys for now but i am working on a full keyboard version..

 

this is a simplified version of the synth ive been using on my last few albums..

 

when the full keyboard version is done ill release the more complex version

 

http://www.soundclick.com/cannabissativa

 

to run load "d1:keys.bas" in basic mode

 

press 3

 

then put 10 for distortion

 

and then the number keys are 1-8 to play notes..

00asynth.atr

Edited April 3, 2010 by Kernal

[krupkaj]

Possibly you're interested in using MIDI-keyboards. This can be hard. A MIDI-keyboard works the best when using the serial ports of the Atari, however, the serial port is handled by the same Pokey chip, so it will use 1 or 2 of its Audio channels to support it. So, that leaves not much spare channels. However, writing a software driven MIDI-port, f.e. using one of the joystick-ports, should be an option, but this isn't designed yet as far as I'm correct. So, I wouldn't hope too much for this.

 

But if the Atari is modded with second POKEY (stereo mod) I think you can use all its 4 channels. So at the end it is possible to use up to 6 voices.

[analmux]

Possibly you're interested in using MIDI-keyboards. This can be hard. A MIDI-keyboard works the best when using the serial ports of the Atari, however, the serial port is handled by the same Pokey chip, so it will use 1 or 2 of its Audio channels to support it. So, that leaves not much spare channels. However, writing a software driven MIDI-port, f.e. using one of the joystick-ports, should be an option, but this isn't designed yet as far as I'm correct. So, I wouldn't hope too much for this.

 

But if the Atari is modded with second POKEY (stereo mod) I think you can use all its 4 channels. So at the end it is possible to use up to 6 voices.

 

Well, the stolen channels is not the only problem. I tried once, and you'll clearly hear the IO datastreams from the MIDI-keyboard as disturbing clicks. Just like cassette or disk input (even in so called 'silent mode').

[simonl]

Well, the stolen channels is not the only problem. I tried once, and you'll clearly hear the IO datastreams from the MIDI-keyboard as disturbing clicks. Just like cassette or disk input (even in so called 'silent mode').

It's maybe better to use some 1970s synth technology rather than MIDI. CV/Gate or CV/S-TRIG is much more suitable for controlling the Atari from a keyboard, given that the range of the CV is generally 0-5v you could just read that from the joystick ports using POT0-3 and get the gates from PTRIG0-3 giving you 4 inputs and virtually no CPU overhead. It's probably best to design a simple input circuit to limit the voltage to the acceptable range (some CV keyboards unhelpfully go up to about 10V) and provide appropriate jacks. All you need then is a lookup table switchable between Hz/V or Oct/V (depending on what your source is) to the 8 and 16 bit AUDF values. You could use a MIDI-CV converter if you want to drive it from a MIDI keyboard or sequencer. If you get a multichannel MIDI-CV you could control a whole pile of them, as per the original post.

[analmux]

Well, to be honest, I once had a Solina Eminent electronic organ, a 1970ies instrument. I had no spare room for it left, and it was a bit getting dusty, and not working properly, so I totally decomposed the instrument, and saved the two keyboards. These are just simple 'contact' keyboards, so should be simple to implement. One idea was to use two 6526 ICs (from the commodore 64, I have loads of these chips:) ), as it can be used as a 8*8 key matrix port, just as it WAS used in the C64. So, 64 keys can be addressed by this.

 

Another idea I had was using the Atari as main sequencing device, with just a MIDI-keyboard connected to the SIO port, but making 8 external boards, each with a SID + 6510 CPU + 64kB RAM, just to make a 24 channel octal SID device: i.e. with 24 channels synth or 24 channels 8bit sampling. Last time I'm rethinking whether it could be done, and the most important, why to do it. And I really think it would be a great instrument to have and to play on. So, maybe I'm going to really build this.

[simonl]

Well, to be honest, I once had a Solina Eminent electronic organ, a 1970ies instrument. I had no spare room for it left, and it was a bit getting dusty, and not working properly, so I totally decomposed the instrument, and saved the two keyboards. These are just simple 'contact' keyboards, so should be simple to implement. One idea was to use two 6526 ICs (from the commodore 64, I have loads of these chips:) ), as it can be used as a 8*8 key matrix port, just as it WAS used in the C64. So, 64 keys can be addressed by this.

 

Another idea I had was using the Atari as main sequencing device, with just a MIDI-keyboard connected to the SIO port, but making 8 external boards, each with a SID + 6510 CPU + 64kB RAM, just to make a 24 channel octal SID device: i.e. with 24 channels synth or 24 channels 8bit sampling. Last time I'm rethinking whether it could be done, and the most important, why to do it. And I really think it would be a great instrument to have and to play on. So, maybe I'm going to really build this.

 

Cool, I'd say go for it on both projects, even better if you combine the two If you made a video of the results, you might be obliged to wear a Rick Wakeman style cape though.

[Hornpipe2]

Thanks for all the replies, you guys. I understand a lot better about this now, and it seems like a worthy project - I love the Atari sound.

 

Also - does RMT produce files with any kind of visualization, so they could be projected on a screen or something at a show?