This is a pretty good disassembler for the PDP-8 with a powerful mechanism for refining the disassembly.
The source has been lost, but at some point, some intrepid soul will feed DCP to itself and regenerate it.
There are two differen tools, DCP16 an DCP24. The former fits into 16K of memory. The latter, consuming 24K, does a richer job of interpreting EAE (Extended Arithmetic Element) instructions, and a richer INFO file to refine the disassembly.
The documentation in DCP.WU is adequate to make sense of using the program.
Upstream is from bitsavers.org and replicated at dbit.com and The deramp.com Vintage Computing Archive.