I knew a woman whose sole job was maintaining COBOL servers for IBM. She did it for close to 20 years before they updated those servers a few years ago. Not even her supervisor knew how to check her work. lol

I was part of a team that was trained in COBOL to help update code in time for Y2K. We’ve been headhunted by the same company several times in the last ten years to further update and maintain the same code, originally written in the mid-1970s. I’m now 56, and I suspect that code base will live at least as long as I do.

My great uncle worked in cobol on a Ge225 for the us army and then several banks. To program they had to print them out on punch cards. Once you loaded the programs they then had to set up a completely different algorithm for each bank as it sent in data because nothing had been standardized and they each had their own system. Once you did set up the banks’ approved formulas in their module of code, this computer could do operations on the data coming in over a connection. These computers were already on a phone line to the banks way before Internet was a concept!

Here’s a fun manual from the successor called the GE 235. http://s3data.computerhistory.org/brochures/ge.235.1964.102646091.pdf