Texas Instruments LPC Speech Chips

The Texas Instruments LPC Speech Chips are a series of speech synthesizer DSP ICs 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 the speech department dissolved in late 2001. The rights to the MSP line, the last remaining line of TI speech products as of 2001, were sold to Sensory Inc. in October 2001.^[1]

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,^[2] and Gene A. Frantz^[3] and its silicon was laid out by Larry Brantingham.^[1] The chip was designed for the 'Spelling Bee' project at TI, which later became the Speak & Spell.^[1] A speech-less 'Spelling B' was released at the same time as the Speak & Spell.^[4]

All TI LPC speech chips until the TSP50cxx series used PMOS architecture, and LPC-10 encoding in a special TI-specific format.^[5] 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

1978:

• TMS5100 (AKA CD2801 AKA TMC0281, internal TI name is '0280' hence chip is sometimes labeled TMC0280): First LPC speech chip. Used a custom 4-bit serial interface using TMS6100 or TMS6125 mask ROM ICs; used on all non-super versions of the Speak & Spell,^[6][7] Speak & Math,^[8] Speak & Read,^[9] and the TI Language Translator/Language Tutor.^[10] Publicly sold as TMS5100. It was also used on the Byron Petite Electronic Talking Typewriter^[1][11] toy. Superseded in 1979 by TMS5100A and TMS5110.

1979 or 1980:

• TMS5100A: Die shrink of TMS5100. No difference whatsoever in function, supposedly.
• TMS5110: New version of TMS5100, has updated LPC tables (which mostly match 5220, see below). Pin, but not function compatible with TMS5100. Superseded by TMS5110A.
• TMS5200 (AKA CD2501E, internal TI name is '0285' hence chip is sometimes labeled TMC0285): Added 8-bit parallel FIFO interface; designed for use by the TI consumer division for the TI 99/4A speech module; also used on the 4th generation Bally/Midway pinball tables' Squawk and Talk speech board (part number AS-2518-61), on the Environmental cabinet version of the Bally/Midway arcade game Discs of TRON, on (earlier) Apple II Echo 2 cards, and on the Zaccaria arcade games Jack Rabbit and Money Money. Superseded by TMS5220 in late 1980/1981, and possibly sold as cheap, 'fire-sale' stock in 1982–1983.

1980:

• CD2802: A version of the TMS5100/5110 with different LPC and Chirp tables, not the same as either the TMS5100(A) or TMS5110(A). Used on the Touch and Tell only, never sold outside of the company, except possibly as the little-known "TMS5111".^[12][13]
• TMS5110A (after 1985: TSP5110A): Die shrink of TMS5110, pin and function compatible. Used on at least two home computer products. It was used on the arcade game Bagman by Valadon Automation, and on the arcade game A.D. 2083 by Midcoin. Used on the Chrysler Electronic Voice Alert vehicle monitoring system.

1980 or 1981:

• TMS5220 (AKA CD2805E?): Improved version of the TMS5200, pin but not function compatible (has new LPC tables and a new chirp table); used on (later) Apple II Echo 2 cards, (rumor) on the very last run of TI 99/4A speech modules, on the BBC Micro, in Bally/Midway's NFL Football arcade game, and in many Atari, Inc. arcade games, including Star Wars, Firefox, Return of the Jedi, Road Runner, The Empire Strikes Back. Later Atari arcade games used the TMS5220C, see below. The TMS5220 was also used on Venture Line's Looping and Sky Bumper, Olympia's Portraits, and Exidy's Victory and Victor Banana arcade machines.^[14] Superseded by TMS5220C in 1983/1984.

1983:

• TMS5220C (after 1985: TSP5220C): has the two NOP commands the parallel FIFO interface reworked to control speech rate, added external full reset; minor change apparent to the way energy values affect unvoiced frames. Otherwise identical, pin-compatible, and a drop-in replacement to the TMS5220. Used on the Atari arcade games Indiana Jones and the Temple of Doom, 720°, Gauntlet, Gauntlet II, A.P.B., Paperboy, RoadBlasters, Vindicators Part II, and finally Escape from the Planet of the Robot Monsters. Also used on the IBM PS/2 Speech Adapter and the PES Speech adapter. Manufactured into the early '90s.

1985:

• TSP50C50: CMOS, uses LPC-12 instead of LPC-10, uses TMS60C20 256Kb/32KiB serial ROM instead of TMS6100. Uses 'D6' LPC tables and chirp tables, which were common for the whole TSP50Cxx series. Has built in low-pass analog filter. Manufactured into the early '90s.

1986:

• TSP50C40 (later MSP50C40): TSP50C50 plus a simple 8-bit microcontroller with on-chip mask ROM. Was used in a number of TI's consumer division products. was named CM54129/CM54169 for the speak&music.^[15]

1987 and later:

• Several other TSP50Cxx products, which added more ROM/ram, did away with the serial interface entirely, etc. One even did LPC-10 and had support for the old TMS5220 ROMs, supposedly.
• After about 1997, the TSP non-microcontroller line was phased out in favor of the MSP line, which had microcontrollers. In October 2001, the rights to the MSP line of chips was sold by TI to Sensory Inc. Sensory rebranded the chips as the Sensory SC-6x line.
• In October 2007, Sensory announced it would no longer accept new mask submissions for the SC-6x line. Orders for chips with existing masks will continue to be accepted for at least the next year.

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 (aka TMC0355 aka TMS7125) read-only memories which were mask programmed with words required for a specific product.^[5] 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.

The TMS5200 appears to be identical to the TMS5220 in operation, but its voice output sounds rather different and more distorted. According to private correspondence with Larry Brantingham, the TMS5220 is an improved version of the TMS5200 with a new chirp table, a new table of LPC coefficients, and a new statistical modeling feature on the encoder software used at TI.

References

Additional points of interest

ftp://ftp.whtech.com/datasheets%20and%20manuals/Datasheets%20-%20TI/TMS5220.PDF - TMS5220 datasheet

http://uk.youtube.com/watch?v=wVDE-6TtmFQ - Demonstration of TMS5220 via emulation and demo of QBOX Pro software.