As the [man page] for [tclvars] mentions, one can examine [TBC] by
generation of [Tcl] with '''TCL_COMPILE_DEBUG''', followed by 
execution in a run-time context with at least one of [tcl_traceCompile]
and '''tcl_traceExec''' non-zero.

[DKF] provides a different formula, relying on '''--enable-symbols=compile''', 
in this
[http://groups.google.com/group/comp.lang.tcl/msg/1204437fb12839e1]
[comp.lang.tcl] posting.

[Tcl 8.5] now has the '''`[tcl::unsupported::disassemble]`''' command, which is available in even non-symbols builds of Tcl and which generates output in a much more useful way (i.e. as a Tcl result, not by printing directly to C stdout).

[Tcl 8.6.3] now has the '''`[tcl::unsupported::getbytecode]`''' command, which is designed to be much easier for scripts to work with. It's output is only ''technically'' human-readable, being a large [dict]ionary…

<<categories>> Internals | Introspection