My good friend Bob,
Well said, but there's more to say.
z/XDC is a product that has changed z/OS software development forever.
Before z/XDC, debugging software was a dark art. Some techniques I used
were intentional ABENDs, WTOs, marking control blocks with footprints,
and other methods too obscure to mention. It was tedious, error-prone,
and time-consuming. Another option was running z/OS under VM. It worked,
but required a dedicated z/OS system, an expensive luxury.
Of course we all know why z/XDC is a great product, and that has to be
Dave Cole. He designed z/XDC the way it is because he himself was down
in the trenches debugging himself. Every time he debugged, he thought of
a new feature to add to z/XDC, and that is why it is a great product,
perhaps one of the greatest products ever written. Dave labored in
obscurity for years as we have all done.
Writing software to exploit zIIPs would be extremely difficult without
z/XDC SRB support. And Dave made it happen.
I remember so many classes given by Bob. I know z/XDC well, but every
time Bob taught me something new. The product has depth and a richness
which makes it special.
For many years now I have built z/XDC into my own products, allowing me
to trap with a multitude of conditions via operator commands. Of course,
this is protected.
z/XDC is one of the products like seat heaters in a car: once you start
using it there is no going back. For many including myself, it is a
condition of employment.
Thank you, Bob.
Tom Harper
Phoenix Software International.
On 11/9/2025 7:33 AM, Bob Shimizu wrote:
All:
Good question, Steff. Here we go.
First, I must admit my bias. For 35 years I worked with every
customer Cole Software had, serving as Cole Software's Instructor for
many of those years. Some of you on this list know me. Many more know
the product and Dave Cole, its progenitor.
z/XDC was, and is aimed at Assembler professionals. These people
spend decades learning their craft, much of which is spent
encompassing a devilishly complex environment, z/OS itself.
Based upon the observations of these true coders, z/XDC is the best
thing out there. Nothing else brings the clarity to debugging that
other tools do.
Nothing else allows you to work on APF-authorized, or multitasking
code as easily. It's VASTLY better than causing one dump at a time
and puzzling out what may be going on inside the architecture.
Instead, each Trace or Breakpoint in z/XDC serves as a dump, allowing
you to look all around the A-space (or indeed the system itself) at
each point.
Based upon MY observations, I remember lots of "AHA!" moments in the
classes I taught, wherein one or more people would agree, "We WISH we
had this ability years ago!"
LIST PSW F (decodes the PSW so you don't have to interpret the blasted
thing).
LIST TASKS (BANG. There's the task structure for this (or any other)
address space).
FORMAT <adders-expression>. Disassemble ANYWHERE. If ADATA is
available to z/XDC you see source code. If C source code is available
you see your C statements. If nothing is available, you get
disassembled object code).
That's not even a hundredth of the commands out there in the product.
z/XDC's interface is clunky. It's a retooled 3270 "thing" that most
new people hate. It can be learned. There is active work being done
on a GUI, and that should bring z/XDC into the 21st Century at last.
Like the z/XDC product itself, z/XDC's documentation is comprehensive,
authoritative and absolutely impenetrable to the casual observer. In
essence the product's documentation is a "dump" of the internal Help
Subsystem (which requires learning in order to navigate).
That is why I wrote several books that attempt to bring z/XDC out into
the light, illuminating it's major features and smoothing the way to
understanding. I would suggest that you begin with the z/XDC Primer,
which uses one of our internal programs as a test bed. You won't have
to have the product active to learn and understand what the tool does.
Go here and scroll to the bottom of this page.
<https://colesoft.com/support/zxdc-release-z22?_gl=1*1wj2fs*_ga*MzkyODkxMTQ3LjE3NjI3MDIzMDE.*_ga_NN1M65S85L*czE3NjI3MDIzMDAkbzEkZzAkdDE3NjI3MDIzMDAkajYwJGwwJGgw>
I no longer work for Cole Software, but I haven't lost my chops.
Steff, please, what are your questions? What aspects of Assembler
give you the most grief? What challenges do you face in your work
with Assembler under z/OS? I may be able to point you in the right
direction.
My contemporary, Frank Chu (CC'd) is one of the product's Senior
Developers. Frank can answer any of your deeper questions. He's also
a helpful guy. He'll be happy to guide you further if/when I can't
take you any further.
Sincerely,
Bob
On 11/9/25 04:12, Steff Gladstone wrote:
We are looking into acquiring an assembler debugging tool. Nearly two
decades ago I used the z/XDC tool at an earlier employer. Is this tool
still considered top-of-the-line? Are there other tools considered more
powerful or friendly?
Thanks,
Steff Gladstone
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