Speak & spells or any other item that I know off hand doesn't use the SN76477 chip except for the Synare Electric Drums
Here's an examplehttp://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... eName=WDVW
There are two chips out there you can look for. The SN76477 and the SN76477N one is a smaller dip size than the other.
TI also had another chip which was it's little brother called the SN94281.
You could use the chip inside the speak but you'd have to build a processor to control the phonemes that are stored on the chip. That's a lot of work unless you have a Z80 lying around. Saw an article where it depicted how to write the program to interface with the chip and make noises with it.