TCSM2 transcoder cards¶

Officially, the correct transcoder card for E1-based TCSM2 systems is TR16 (or TR16-S, or TR16-T), while the correct TR card for T1-based TCSM2 systems is TR12 (or its -S or -T later incarnations). It is clear that a TR12 card won't work with E1-based A interface: 16 TRAU DSP channels are needed to cover one half of an E1 trunk, but only 12 would be present. But the opposite direction is much less clear: what would happen if TR16 cards are installed when TRCO is configured for ANSI mode and the Exchange Terminal is ET2A? Would it still work, leaving the 4 extra DSPs unused, or would it fail because of some other gotcha? I also wonder how TR12 cards differ physically from TR16: did they take the same PCB and simply omit 4 TRAU DSP channels, or is it truly a different board?

In any case, I (falconia) only have TR16-S boards currently, hence the latter hw is the only version I can comment on.

TR16-S hardware notes¶

Individual DSP channels¶

There are 16 identical DSP chips on the board; the markings on each chip consist of a TI logo and these 3 lines:

TRLPRB 1.1
D36884PZ-66
ADW-4BAORLW

This chip appears to be a Skunkworks part made for Nokia by TI - it seems that TI had a strong Skunkworks division in those days, making custom chips for various parties. Based on the historical period from which this design originates, my educated guess is that the DSP family is most likely C54x, same as our beloved Calypso.

There is also a 64Kx16 static RAM chip next to each DSP, IDT 71V016. Of course we can only guess if this SRAM is used for downloaded code or dynamic data or both, and what kind of RAM and ROM are implemented inside the DSP chip itself.

Global per-board components¶

The most prominent "global" component is Lattice ispLSI1032E; while Nokia's documentation calls it an FPGA, it is actually a CPLD with non-volatile configuration bits inside. (FPGAs load their configuration bitstream from an external serial flash chip; CPLDs with internal non-volatile configuration are live from power-up, as if they were fused.)

A 128Kx8 static RAM chip is also visible, CY62128BLL-70SI.