+1 for Sonic Charge's Bitspeek

I love this plug. Also:

http://www.plogue.com/products/chipspeech/
http://blog.wavosaur.com/text-to-speech … audiounit/

Sonic Charge's Bitspeek is your one stop VST for this kind of thing.

I know you stated you want it to be done with a microphone, but there is a new piece of musical software called chipseech that just came out. It's purpose is to emulate old voice synthesis programs from the 1980s and its very easy to use. The voices have a robotic, almost "chip" style so you might find it useful. There are some features that allow for what you want, I believe, so I think it's worth checking out. Hopefully this helps!

along this line, you could just feed your vocoder's filter bank with some chippy synth and modulate that w/ voice

Eventually I'm gonna try to use the Moonbase Alpha voice synth and sample it on a game boy.

You could use a combination of vocoder and bit crusher. Audacity is a free program with both plugins. The simplest work flow would be to take a vocal sample of speech as a wav. file., reverse it, then assign random notes to it through a vocoder plug in. Once you have a suitable robot esque inflection, apply the bitcrusher to give it a lo bit sound quality. You could then apply random splices manually and reorder the snippets of audio to give it an even more broken feel.

Hello everyone, first of all sorry for my bad english, i'm french and no realy good in this language.

For a animated series in voxel, I need to create two voices for two characters. There voices must look like a human voice (with intonation/inflexion) but not understandable, a bit like R2-D2. After what I'll match the dialogue sound with subtitles for the comprehension.
All in 8 bit of course.

So i search for a device, or softwar who can do that simply, possibly with a microphone (I think i don't need complicated features, cause i tried with some softwares but you know, i'm a noob in that stuff )

That's all, if you have an idea, thank you ^^ .