X-no-Archive:yes
We have it; I've made some use of it, and it met the needs of the moment. It
is pretty typical in that it starts the program to debug at the first
executable line, indicated with a right angle bracket and all lines numbered
as they are in the compile listing, and has a status line separator from a
command area below, and you can otherwise move through the code to view what
you will. I recall it being measurably CPU-intensive, so avoided using it on
our product platform, although using Glance to see this was probably worse
than the debugger itself.

It is useable, although its interface is dated. The commands are mnemonics,
one or two letters mostly, with the longest being the command 'update'.
Contrast this to the Trax debugger version, which I used four years ago, so
this may have changed, where you can spell out step or use just the letter
s. IIRC, you can hit enter in either product to repeat the last command. Or,
contrast this with the MicroFocus character-based debugger called Animator
(which I have only used in the PC environment, and have no experience with
the MPE version), which can use overlay 'windows' and presents a 'menu' of
sorts, so the single letters are menu choices instead of command . That's
not much of a difference in use, but an important one for interface.
Animator also uses function keys; the Symbolic Debugger (also known as XDB)
does not.

It has some idiosyncrasies. For instance, there is no exit command, it's
quit, and then it asks you "Really quit?". So that's a bit different. Help
is more like a man page, than what we are used to in MPE help - keep your
manual handy and start your cheat sheet. At least, that's what I have to do,
although I use it infrequently.

You do have to compile and then link for debugging. I think there are
actually two ways to achieve this, either as documented, compiling in one
step then linking with the XDB library, or compiling and linking in one step
with COB85XLK (which is how we normally compile anyway), then adding the XDB
library in link editor. Either way, it's two steps, and so probably means
some change from what you are used to. IIRC, you do have to produce a
compile listing.

When I first tried to get information from HP on this, about four years ago,
I found people either knew it by product name, Symbolic Debugger, or knew it
as XDB, which is the command as well as the name in the banner (!). At the
time, almost no one I talked to seemed to know that they are one and the
same.

I have no particular preference among the three debuggers mentioned, and
could be just as happy and productive using either. We went with XDB here
because it was relatively inexpensive, although I don't know how the price
compares with Trax, and because of my preference not to deal with one vendor
for our compiler and another for our debugger (in contrast to Trax). The
only call I remember to HPRC for this was about setting the parm switch for
invoking the USE-FOR-DEBUGGING SECTION while debugging with XDB or something
similarly obscure, and they did get me the answer (in XDB, enter b, then
r;parm=1). While that's not something most of us will do on a regular basis,
my point is that I was able to get support in a typical amount of time and
get an answer that did what I needed.

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your mileage.