On 24/06/2026 1:34 am, Phil Smith III wrote:
Yes, it does depend on what you mean by "AI", and I'm afraid I was unclear.
I really meant two things:
1) "Is anyone actually exploiting Telum?" and
2) "Is anyone doing any LLM stuff?"
I think current LLMs are beyond what can reasonably run on the
mainframe. Abilities and expectations require too much computing power.
But I have been experimenting with LLMs for mainframe related stuff.
- I tried to get it to write some assembler. It generated about 150
lines of convincing assembler, but that was about 130 lines more than I
thought I needed and didn't actually assemble so I ended up writing it
by hand. However, it was quite good at answering questions about HOW to
do things (not always correct! but often opening new lines of thought),
finding examples and explaining what examples were doing, so from that
point of view it was useful.
- It is very good at analyzing Java and C code and finding problems or
pointing out potential problems.
- It's good at Java so if I point it at my Java SMF reporting samples
and say "write me a new SMF report showing ..." it generally does a good job
- It occasionally does annoying things like using em dash in comments,
which meant that git checkouts on z/OS always showed as modified due to
UTF8-EBCDIC transalation problem
- More complex code definitely requires someone to review it. A couple
of common problems:
1) Swallowing errors. It writes code to handle a problem and continue
when the problem should result in the program failing.
2) Every so often code seems to reach critical mass and explode. It
generates hundreds of lines of code for simple functions. You have to go
in and prune and simplify, otherwise it ends up unmaintainable.
I'm sure that it could do better if I chose different models or used
better prompts and rules. Prompts often feel a bit like a
non-deterministic programming language.
Overall LLMs are incredible, but they seem like a productivity tool
rather than something that should work unsupervised.
--
Andrew Rowley
Black Hill Software
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