What was a Terminal Concentration Device in DEC's products?

From the books, the kmc11 had an "lsi11 on board", 1k of 16 bit ram, 1k of 8 bit data memory a 300ns cycle time, 16 bit microprossor with a 16 bit micro-instruction bus and 8 bit data path. This is according to the 1980 Terminal and Communications handbook, so it's a few years after the 1976 timeframe of Sha Tin. Now the original LSI11 processor was 4 main chips, an EIS/FIS chip (or the CIS lite chip or the weird 1k*20 bit micro-ram board which I have somewhere). The DCT11 was a single chip lsi11 that had an 8 or 16 bit outside bus and a 16 bit internal structure and ran pdp11 instructions. So the KMC11 probably had the DCT11 chip. The LSI11 chipset was around in 1975, so it makes sense that DEC could use it. The SBC11/21 came out in 1981 but the chip was probably avail internally by 1980 so I'm guessing that the KMC11 and the COMM-IO-DP was using the DCT11.