Texas Instruments LPC Speech Chips

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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]

1 Theory
2 History
3 TI LPC Speech chip family:
4 References

[edit] 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.

[edit] History

The TMC0280 was the first self-contained LPC speech synthesizer IC ever made. It was designed for Texas Instruments by George Lawrence "Larry" Brantingham, Paul S. Breedlove, Richard H. Wiggins, and Gene A. Frantz^[2] 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.^[3]

All TI LPC speech chips until the TSP50cxx series used PMOS architecture, and LPC-10 encoding in a special TI-specific format. ^[4] 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.

[edit] TI LPC Speech chip family:

1978:

TMS5100 (AKA TMC0281, internal TI name is '0280'): First LPC speech chip. Used a custom 4-bit serial interface using TMS6100 or TMS6125 mask ROM ICs; used on the original Speak & Spell, and publicly sold as TMS5100. It was also possibly used on the Byron Petite Electronic Talking Typewriter^[5]^[1] toy (though it may have been misremembered and the toy may actually use a TMS5110A). Superseded in 1980 by TMS5110 and TMS5110A.

1979 or 1980:

TMS5100A (AKA TMC0281): Die shrink of TMS5100. No difference whatsoever in function, supposedly.
TMS5110 (AKA CD2801 (early chips), AKA TMC0280, internal TI name unknown, may be '0281' or more likely '0282'): New version of TMS5100, has updated LPC tables (which mostly match 5220, see below). Pin, but not function compatible with TMS5100. Used in the 1980 TI consumer division units (i.e. Speak & Math 1980 version, and several international Speak&Spell variants, and possibly some early Speak & Read units.^[6] (All later consumer division units use the TMS5110A marked as CD2802 or CD2801?) Superseded by TMS5110A.

1980:

TMS5110A (after 1985: TSP5110A) (AKA CD2802 and later CD2801 chips): Die shrink of TMS5110, pin and function compatible. Used on Touch&Tell and later TI Consumer division units. Used on at least two home computer products (source? names?). 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. It also possibly may be used instead of the TMS5100 on the Byron Petite Electronic Talking Typewriter toy.
TMS5200 (AKA TMC0285 AKA CD2501E, internal TI name '0285'): Added 8-bit parallel FIFO interface; designed for use by the TI consuper division for the TI 99/4A speech module; also used on the 4th generation Bally pinball tables' Squawk and Talk speech board (part number AS-2518-61), on (earlier) Apple II Echo2 cards, and on the Zaccaria arcade games Jack Rabbit and Money Money. Superseded by TMS5220 in late 1981/1982, and possibly sold as cheap, 'fire-sale' stock in 1982–1983.

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 Echo2 cards, on the very last run of TI 99/4A speech modules, on the BBC Micro, in Bally/Midway's Discs of TRON and NFL Football arcade games, and in many Atari arcade games, including Star Wars, Firefox, Paperboy, Return of the Jedi, Gauntlet, Indiana Jones and the Temple of Doom, Road Runner, The Empire Strikes Back, 720°, Gauntlet II, A.P.B., RoadBlasters, Vindicators Part II, and finally Escape from the Planet of the Robot Monsters. 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.^[7] 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; otherwise identical, pin-compatible, and a drop-in replacement to the TMS5220. 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 encoding. 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. ^[6]

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 16Kbit (2KiB) TMS6125NL (aka TMC0355) read-only memories which were mask programmed with words required for a specific product. ^[4] ALL versions of the LPC chips until the TSP50Cxx series support them. All versions of the TMS6100 appear to only have 128Kb/16Kib of content, regardless of rumors to the contrary. The ?TMS7125?, an unusual variant of the TMS6125, had 32Kbit/4KiB of content instead of the usual 16Kbit/2KiB, contained both of the available 'pages' of address space of the TMS6125 on one chip, thereby effectively squishing two TMS6125s onto one die. At least one of the TI example/sample voice chips uses this variant.

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.