http://web.archive.org/web/20051221230405/http://ilhom.host.chat.uz/singen.zip About 30k Produces Sine Wave,Square wave and white noise signals Quite useful for sound therapy,audio professionals,etc...
square waves are easy to generate with computers simply by switching a signal between HI and LO levels. sawtooth can be produced using "register overflow" behavior where the output level of a signal is controlled by a register incremented via a timer interrupt (it overflows and returns back to zero, over and over). triangle wave would be similar to produce, sine waves are a little bit harder, but can afaik can be easily produced using PWM and low pass filtering. since computers can't truly generate anything random, noise is a bit harder but shift registers can be configured in such a way that the output of the last shift register is given as "feedback" to the first shift register. of course you don't need something as complex as a $2 programmable micro-controller that you can code this, but I'm not that double E to tell ya how and it's hard to get things less expensive yet be so versatile as a $2 programmable computer :/
I have a synth program on my laptop that produces sine and square waves. I think my sequencing program may have that capacity as well. Not too sure on Ableton but 100% on Omnisphere. Lol. I never use either of those programs anymore. I used to think synthesizers could be used to create music!
I meant to mention the DTMF tones that POTS (telephones) use for building various things that you could use as a "phone" ... easiest way to generate those tones would probably be to take apart an old phone ... or use free software like audacity that can generate DTMF tones. http://vocaroo.com/i/s0BINBO6XZnU as for making music ... i'm sure someone that say, knew music theory well could produce fine music with a telephone.
