Texas Instruments LPC Speech Chips
The Texas Instruments LPC Speech Chips are a series of speech synthesizer digital signal processor integrated circuits created by Texas Instruments beginning in 1978. They continued to be developed and marketed for many years, though the speech department moved around several times within TI until finally dissolving in late 2001. The rights to the speech-specific subset of the MSP line, the last remaining line of TI speech products as of 2001, were sold to Sensory, Inc. in October 2001. Theory. Speech data is stored through pitch-excited linear predictive coding (PE-LPC), where words  are created by a lattice filter, selectably fed by either an excitation ROM (containing a glottal pulse waveform) or an LFSR (linear feedback shift register) noise generator. Linear predictive coding achieves a vast reduction in data volume needed to recreate intelligible speech data. History. The TMC0280/TMS5100 was the first self-contained LPC speech synthesizer IC ever made. It was designed for Texas Instruments by Larry Brantingham, Paul S. Breedlove, Richard H. Wiggins, and Gene A. Frantz and its silicon was laid out by Larry Brantingham. The chip was designed for the 'Spelling Bee' project at TI, which later became  the Speak & Spell. A speech-less 'Spelling B' was released at the same time as the Speak & Spell. All TI LPC speech chips until the TSP50cxx series used PMOS architecture, and LPC-10 encoding in a special TI-specific format. Chips in the TI LPC speech series were labeled as TMCxxxx or CDxxxx when used by TI's consumer product division, or labeled as TMS5xxx (later TSP5xxx) when sold to 3rd parties. TI LPC Speech chip family. 1987 and later. The companion devices to all versions of the speech chip were the custom 4-bit-interfaced 128Kbit (16KiB) TMS6100NL (AKA TMC0350 ) and 32Kbit (4KiB) TMS6125NL (a.k.a. TMC0355 a.k.a. TMS7125) read-only memories which were mask programmed with words required for a specific product. ALL versions of the LPC chips until the TSP50Cxx series support them. All versions of the TMS6100 appear to only have 128Kbit/16KiB of content, regardless of rumors to the contrary.