Up until 5 years ago, my employer's primary system (government, property tax assessment, billing, and collection) was from a company that had gone belly-up in t

Up until 5 years ago, my employer's primary system (government, property tax assessment, billing, and collection) was from a company that had gone belly-up in the early 90's. We fortunately had the source, but it ran on a VERY legacy database called Unidata because it had originally be developed on the Pick operating system. Unidata was/is a Multivalue Database with a built in BASIC programming language. By the time 2014 rolled around there was one programmer in the organization that understood the system, and he was responsible for all code changes. I half-joked with management that we needed an insurance policy on his life/ability to work, because if we lost him, it would put us in a very difficult position, and that software accounted for 90% of our revenue (as well as a lot of the revenue that went to all the local towns and school districts for their operations.) That employee was also nearing retirement (he is retired now.) Fortunately we were able to successfully migrate off of that application, though we keep a minimal license pool to the old system so people can validate pre-migration data against post migration data.