I am part of a small team that maintains a legacy point of sale system that is still used by thousands of stores around the world. It started life as a DOS appl

I am part of a small team that maintains a legacy point of sale system that is still used by thousands of stores around the world. It started life as a DOS application written in C with some ASM bits, and has since accumulated some C++ and C#. There are functions over 5000 lines long. Files over 50000. Global all over the place. It can be a challenge sometimes, but after almost 30 years, it still brings in millions of dollars a year in maintenance and enhancements, and still processes millions of transactions for those retailers.