
TECHNICAL OVERVIEW




[The following material is excerpted from the Intellivoice (Model 3330) Product 
Engineering Specification by Thomas L. Randolph, project engineer, March 18, 1982, 
revised May 6, 1982; from the General Instruments Product Specification for the Orator 
Speech Processor; and from the Intellivoice Service Manual.]



The 3330 produces audio speech signals when used in conjunction with a Master Component 
and/or Keyboard Component, and Voice Compatible game cartridges. Cartridges are deemed 
"Voice Compatible" if they make use of the 3330 speech facilities. Cartridges which are 
not voice compatible do not make use of the speech facilities, nor allow certain of the 
required speech production signal functions to be performed. Nonetheless, non-voice 
compatible game cartridges can be used with the 3330, but no voice game-play enhancement 
is provided.



When used in game-play, the Intellivoice unit "speaks" through the sound channel of 
the television. It uses the same audio channel as the sound generator in the Master 
Component.



A volume control on the 3330 allows variance of the voice loudness level. This control 
does not affect the normal game sounds--only voice.



The 3330 unit will be the base for future peripherals. Additional hardware was 
included to provide for controlled communication between the Master Component and 
those peripherals. Future peripherals will plug into the top-mounted connector of the 3330.



The 3330 consists of a VLSI speech synthesizer, an LSI buffer/interface chip, an active 
audio filter/amplifier section, and provisions for current assistance to the Master/Keyboard 
Component's +5V power supply.



SPEECH SYNTHESIZER

The speech synthesizer is the General Instruments SP-0256 Orator. The SP-0256 incorporates 
four basic functions:





•A software programmable digital filter that can be made to model a VOCAL TRACT.

•A 16K ROM which stores both speech data (Resident ROM or RESROM) and instructions (the PROGRAM).

•A MICROCONTROLLER which controls the data flow from the ROM to the digital filter, the 
assembly of the "word strings" necessary for linking speech elements together, and 
the amplitude and pitch information to excite the digital filter.

•A PULSE WIDTH MODULATOR that creates a digital output which is converted to an analog 
signal when filtered by an external low pass filter.




The SP-0256 can also accept serial speech data from an external source.



For the 3330, the RESROM contains a variety of words and phrases that may be useful in
video games. The PROGRAM consists of 17 different parameters used by the VOCAL TRACT model 
to imitate human speech patterns.



BUFFER/INTERFACE CHIP

The buffer/interface chip (General Instruments SPB-640) contains logic required to interface 
the speech synthesizer to the Master/Keyboard Component cartridge bus.



Controlling input to the buffer/interface chip is primarily from the Master Component 
Microprocessor bus signals. Other controlling inputs are generated by the speech synthesizer 
during speech production.



The buffer/interface chip has three methods of transmitting data to the speech synthesizer 
and peripherals connected to the stacking connector.



The first speech-oriented data transference method causes the synthesizer to produce 
speech segments contained in its internal ROM (RESROM): the buffer/interface chip allows 
the address of the desired speech segment to pass onto an 8-bit peripheral data bus connecting
the buffer/interface and synthesizer chips, and sets the proper control lines for 
the synthesizer to generate the segment.



The second method of moving speech data allows the Master/Keyboard Component to load custom 
speech data into the synthesizer: data from the game cartridge is loaded into the 
buffer/interface chip's 640-bit FIFO array and converted to serial data, and 
the buffer/interface chip sets the proper control lines for the synthesizer to read the 
serial data and convert it to speech.



Finally, the buffer/interface chip also allows moving data to and from peripherals 
through the top-mounted stacking connector: the buffer/interface chip sets the proper 
control lines for the peripheral bus to carry bi-directional microprocessor data.



ACTIVE AUDIO FILTER/AMPLIFIER SECTION

The output of the speech synthesizer is not conventional audio, but is a 40 KHz digital 
Pulse Width Modulated (PWM) signal. When viewed on an oscilloscope, this appears to be a 
square wave whose edges rapidly expand and contract as speech generation takes place.



A series of filters (an LM-324C Quad OP Amp and related components) converts the PWM 
signal to conventional audio which is then amplified (an LM-358C Dual OP Amp and related 
components, including volume control) and fed to the Master Component.



The effective passband for the speech signals is from 150 Hz to 5KHz. Within this is 
also a 3db/octave bass pre-emphasis.



POWER SUPPLY BOOSTING/SUPPORT
The stacking connector has its connections arranged in such a way as to allow a future 
power supply to fill the 3330 and game cartridge power requirements, and boost the 
power capability of the Master/Keyboard Component's power supply.



Power supply boosting can be accomplished by allowing power input to pin six of the 
stacking connector. This unregulated voltage is applied through an 8.2 Ohm, 2W resistor 
to the Master/Keyboard Component Vcc on pin 43 of the cartridge port to supply an 
approximately 270mA boost.



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