It the 1980s, and legacy systems are already a problem.
IBM is still shipping source code for big-iron internals, says this mainframe pilot fish.IBM discontinued supporting BTAM under CICS, but we had a major customer who communicated via CICS BTAM,& fish says.Translation: The big customer uses the CICS transaction-processing system, and connects to it over telecommunication lines using the very old BTAM protocol — and IBM has just stopped supporting that approach.Boss instructs fish to put BTAM support back in — after all, she does have access to the source code.
Fish thinks that a bad plan, since changing internal mainframe system code is never a good idea.