🚀 go-pugleaf

A long time ago I set up an assembler debugging system to track down a
particularly elusive problem with an RSCS modification (it turned out
to be due to sloppy coding practices by IBM, which IBM refused to fix).
I set up a USERID to run a test version of RSCS, and made my own
USERID a secondary user for it. I used IUCVTRAP to catch the console
messages from RSCS, processed them with Rexx code, and generated CP
commands to be executed on the test RSCS machine. The Rexx code I
wrote essentially did two things. It worked its way through RSCS
control blocks to find the origin address for the modified line
driver. Having done that, it stepped through the code one instruction
at a time. As each instruction in the line driver was executed the
Rexx code displayed the corresponding line of the LISTING file
generated when the line driver was assembled. I managed to find the
bug with just these capabilities, but the general approach I used
could be extended to provide other capabilities, such as
tracking register contents or displaying data areas in their source-
code formats.