Speech synthesis and the C64

Growing up with the Commodore 64 I was completely blown away when several games were released featuring synthesised speech.  In particular, the two noteworthy games I owned back in the day were Impossible Mission by Epyx, and Ghostbusters by Activision.

Anyone who owned these games will remember the speech samples for "Destroy him my robots!", "He slimed me!" and "Ghostbusters!".

It was only recently whilst researching the hardware speech board for the arcade game Berzerk by Stern Elecontronics (1980) that I discovered there's a connection between Berzerk and these Commodore 64 titles featuring speech.

Firstly, here's the game Berzerk in its arcade and home computer guises.  If you don't follow Mamemeister on YouTube already, please do so.

The speech board (VSU-1000) in the arcade cabinet version of Berzerk is based around the Telesensory Systems Inc. S14001A.  You can see the IC (large chip lower, middle) and the ROMs containing the speech data (lower right).
 

Stern Electronics, VSU-1000 Speech Board

The development history of the TSI S14001A integrated circuit for use in the Speech+ talking calculator can be found on this page:

http://www.vintagecalculators.com/html/development_of_the_tsi_speech-.html

There's a great video showing the TSI Speech+ calculator in use.  Notice how the synthesised voice sounds just like the robot voice in Berzerk ("The humanoid must not escape!").

The inventor behind the technology is Forrest S. Mozer and his son Todd.

Electronic Speech Systems (ESS), founded by Forrest S. Mozer, then appears to have developed a software based solution which was used in several Commodore 64 titles, notably: Impossible Mission, Ghostbusters, Kennedy Approach.  Presumably this is the Software Speech (TM) product shown in the credits below.

Ghostbusters by Activision 1984 (Commodore 64)

Loading screen for Activision's Ghostbusters, crediting Software Speech (TM) by Electronic Speech Systems.

Impossible Mission by Epyx 1984 (Commodore 64)

This is the ESS credit from the loading screen of Impossible Mission.  There's an interview with Dennis Caswell (Edge/Retro Gamer) which explains how ESS were asked to produce the speech and never used by Epyx subsequently.

Finally, here's a couple of Commodore 64 demos (Chaos Speech I & II) featuring ripped samples from several games using ESS speech.