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

[Noel Chiappa]

   > From: Chris Zach

   > Maybe that is the dhv11.

The DH11, DHV11 and DHU11 are all very similar, although not 100.00% program compatible.
(The DHQ11 can be set to exactly emulate either the DHV11 or DHU11.) So, all provide
DMA output, but not DMA input.

Differences with the DH11 include two full word registers for DMA address,
hardware ^S/^Q support, built-in diagnostics, etc. The DHV11 and DHU11 differ
in hardware echo, output FIFO, a fix for the infamous DH11 input silo level
bug, etc.

     Noel