One of the first major electronics projects I attempted was to interface a speech synthesis chip, the venerable General Instruments SP0256-AL2, to my Commodore 64 (this was in the late 80's I think). It ended up not being all that hard thanks to excellent schematics in the datasheet and in Robot Builder's Bonanza
The speech chip was a soon-to-be discontinued item I picked up at Radio Shack (I just found a link where you can still buy these). Recently I did some web searches for giggles and I guess people are still using these old ICs but there didn't seem to be a lot of info out there about them.
Since I'm a packrat, I still have the original datasheet that came with the chip. I figured I'd scan it in for anyone out there who lost theirs and are looking for information and details on the chip.
SP0256-AL2.zip (5.2 MB download)
I still have mine on the original breadboard I put it in, with the other components surrounding it like a little forest. At some point I am going to hook it up to my BASIC Stamp 2 and revive it. I never did get the audio amplification working. Afterwards I could interface it to, say, an AVR microcontroller chip and make it accessible to my current and future robots via a much simpler, two-wire, serial I2C interface.