Think you may have lost some digits in your URL ...
https://www.ebay.com/itm/VINTAGE-GI-SPEECH-VOICE-SYNTHESIZER-IC-SP0256A-AL2-CTS256A-AL2-Text-to-Speech/273360299040
As you say it was cool back in its day. There was a Speech ROM for the BBC Micro which was very impressive. Have occasionally looked for the code for that but have never found it.
Modern speech engines are a lot better, actually human sounding, though most of the stuff for the Pi is rather robotic. Google's AIY Voice Kit stuff is probably good if one can figure out how to use it.
Another 'free' option is to use Google's picoTTS which is included in Android phones. MIT App Inventor 2 can easily interface to that and it sounds excellent. The problem there is how to interface to an Android phone.
https://www.ebay.com/itm/VINTAGE-GI-SPEECH-VOICE-SYNTHESIZER-IC-SP0256A-AL2-CTS256A-AL2-Text-to-Speech/273360299040
As you say it was cool back in its day. There was a Speech ROM for the BBC Micro which was very impressive. Have occasionally looked for the code for that but have never found it.
Modern speech engines are a lot better, actually human sounding, though most of the stuff for the Pi is rather robotic. Google's AIY Voice Kit stuff is probably good if one can figure out how to use it.
Another 'free' option is to use Google's picoTTS which is included in Android phones. MIT App Inventor 2 can easily interface to that and it sounds excellent. The problem there is how to interface to an Android phone.