Introduced in 1978, the Speak & Spell wasn't just a child's educational toy, it was a technological breakthrough.
Designed for children 7 years and older, the Speak & Spell was a learning toy. It would say a word, and it was up to the user to spell the word correctly using the machine's 40 key membrane keyboard. There were also built-in games including "Mystery Word" which worked like Hangman, and "Say It" which prompted the user with a displayed word, a pause, and correct pronounciation of that word. The machine also had a "Secret Code" function which translated the letters using the following "algorithm":
ABCDEFGHIJKLMNOPQRSTUVWXYZ
FEDCBAZYXWVUTSRQPONMLKJIHG
The Speak & Spell is equipped with a vocabulary of approximately 100 words. These words are synthesized using the world's first Single-Chip Speech Synthesizer. The Monolithic PMOS Speech Synthesis IC was announced on June 11, 1978 by Texas Instruments. From the press release:
The speech synthesis MOS/LSI integrated circuit along with two 128K dynamic ROMs each with the capacity to store over 100 seconds of speech, and a special version of the TMS 1000 microcomputer, all TI developed, serve as the main electronics for the new talking learning aid, SPEAK & SPELL(TM), for seven year olds and up. The new TI consumer product was introduced at the Summer Consumer Electronics Shows in Chicago, June 11-14.
Speech encoding is achieved through pitch excited Linear Predictive Coding (LPC). As the name implies, LPC is based on a linear equation to formulate a mathematical model of the human vocal tract and an ability to predict a speech sample based on previous ones.
The Speak & Spell was a tremendous success, and eventually spawned two more "Speak &" family toys: The Speak & Read, and Speak & Math. Texas Instruments also introduced the "Super Speak & Spell", as well as the "Speak & Spell Compact", however these versions never sold as well as the original Speak & Spell unit. (The Speak & Spell Mach II is the most popular. The Speak & Spell Mach I didn't have a membrane keyboard. Instead, it used raised keys.)
The most famous appearance of TI's Speak & Spell was from the movie "ET: The Extra Terrestrial" in 1982.
The Texas Instruments Press Release for the Synthesizer chip can be found here:
http://www.ti.com/corp/docs/company/history/pmos.shtml
I wrote this node because a long time ago, I used to have Speak & Spell, Read, and Math. They've been long gone since my mother sold them years ago, but I have just recently acquired a Speak & Spell. I hope to get the other two soon. Truly a remarkable piece of equipment, as well as intense childhood nostalgia.
I cracked that algorithm myself. Fear.