The Conversant platforms were a substantial portion of the product development work but the custom circuit packs were, in many ways, the more important work. Conversant had a team of eight to ten highly qualified circuit designers whose work would be crucial to the evolution and success of the product. In addition to the design of the cards suitable for manufacture by Western Electric, these cards required firmware, all produced by the Conversant team.
The circuit packs for the Model 80 and Model 32 used the Fastech SN/TN form factor. This type of card (a non-Conversant sample image shown below) was extensively used in switching platforms. The SN/TN cards in the Model 80 and Model 32 included cards that terminated analog phone lines (“tip ring” cards), T1 trunks, and signal processing (SP) cards that performed the speech processing functions.
The final evolution of this line of circuit cards would be the CompactPCI form factor. All Conversant models (Conversant 3 and the subsequent MAP platforms) used the ISA form factor. The final chassis, the UCS1000, used CompactPCI cards. (no sample image available)
One of the first changes to the Conversant platform was to migrate away from the Fastech peripheral cards, which required a specialized “external cabinet,” to standard PC peripheral cards based on the ISA bus standard. This allowed the telephone and speech cards to be used in a standard PC chassis or PC expansion cabinet.
Migrating to the ISA bus did pose one problem. That bus did not have predefined or sufficient unassigned paths for the telephony connections. To solve this problem, the Conversant engineers adopted the switching fabric from the AT&T PBX switches. Since the PC backplane didn’t support this additional “switching bus,” it was added as a ribbon cable that daisy chained across the Conversant peripheral cards. By adopting this switching technology, the Conversant became effectively a small, programmable switching system devoted to the specialized tasks of an IVR.
The ISA peripheral cards earned an AYC designation in AT&T/Lucent/Avaya nomenclature. There was a sequence of cards that were built. These included six channel tip-ring cards, several types of T1 cards, the dual channel E1/T1 card shown in the illustration above, and several generations of speech cards. Note that the AYC-21 has two connectors at the “top” of the card where the daisy-chain telephony bus connected.
The speech cards (SP and later SSP cards) were effectively high powered, floating point “computers,” almost supercomputers in their day. Sampling audio, coding it for storage and playback are mathematical operations. These tasks are not extremely compute intensive, but recognition of arbitrary tones, recognition of speech, actual recognition of what was spoken (ASR) and the generation of reasonable quality speech from text strings (TTS) were highly compute intensive. Add to this the dimension that an IVR like Conversant might be doing this type of processing for 24, 48, 72, or more telephony channels simultaneously, and the processing needs were substantial.
The first SP card in this series was the AYC-2 developed in 1987-88. It would be augmented with a “companion card,” the AYC-7 then AYC-7B, in the 1989-90 time frame. These were the Conversant “SP card” and “SP daughter” cards. They would be replaced in the 1994-95 time frame with the “Scalable Signal Processor” or SSP card.
This SSP card would be the last of the ISA form factor SP/SSP cards. According to the lead designer of the SSP card, AT&T/Lucent would sell about $45M worth of these cards in the first four years of its life.
The final evolution of the Conversant circuit cards was to the CompactPCI form factor. All of the Conversant platforms from the Conversant 3 through the MAPs used the ISA form factor. The final platform developed that used CompactPCI was the UCS1000.
The CompactPCI backplane had a front side and a back side. The main portion of the card connected to the front of the backplane and the “connector” portion of the card connected to the rear of the backplane. This allowed the chassis, once rack mounted, to be conveniently and statically cabled from the rear. The front “main” card was hot swappable. This meant that a chassis’ cable connections (accessible on the rear) could be easily reconfigured if required without removal from the rack. If a card malfunctioned, that was typically isolated to the “main” portion of the card and not the “connector” portion. Since that part was hot swappable, a failed board could be replaced without removing the chassis or disconnecting any of the cables in the rear.
(no sample image available)