[Tloewald]

MacinTalk predates the Amiga release (it was released alongside the Mac in 1984, but not officially supported -- it worked fine; Plaintalk became an official component of the Mac in the early 90s and included [terrible] speech recognition).

[vidarh]

Macintalk and narrator.device are both incarnations of SoftVoice's TTS, and descendants of SAM. Since they were both developed on contract, and both for M68k, I'd hazard the guess that the internal TTS engine is substantially the same, and that they both follow SAM's structure fairly closely (I know narrator.device does - it explicitly lets you set formant parameters that mirror SAMs pretty closely)