This area contains re-issues of DDT, a symbolic debugger which can
do multiple process debugging or debugging from a second task,
and which does so with a smaller debug kernel than DEC's, and of
RSX FOCAL, an interpretive language with many extensions. Under
RSX11M, on machines with supervisor mode, it can be gotten to
handle interrupts in FOCAL. It is also possible to do weird stuff
with it like dynamically build program code inside a running 
FOCAL program and get it executed. These are not new, but it's been
awhile since they appeared and they are still useful. FOCAL is one
of the most compact interpreters for the PDP11. (It also runs very
well, thank you, under VAX/RSX.)
Glenn Everhart