I tested it on a l30XE with an 850 interface and on a 1040ST Having both parallel and serial connectors makes Smart Speaker unusually flexible. Any software that can send text to a printer or a modem should be able to make it talk. However, the printer control codes my word processor sent made Smart Speaker choke. Instead of sliding over them silently or pronouncing gibberish, it just stopped. I had to turn it oft to reset it.
Speech synthesis is very difficult.
Words must be built up out of elementary sounds called phonemes, which must be reproduced accurately and strung together smoothly. Some provision must be made for punctuation marks. Pitch, volume and speed must vary to provide expression. Even if you produce a great-sounding system, you still have to deal with the idiosyncracies of the English language. You must teach it, for example, to recognize the differences in tough, cough, though and through.