My very first professional gig, in the mid-1980s, was extending a classified ads application that was used by telephone operators in teh days when you could call a newspaper or magazine and dictate your ad over the phone.

It was written in TurboPascal and saved its data with BTrieve. The whole thing ran under MP/M (a CP/M variant that had the concurrency support we needed) on a closely coupled network: A box with an S-100 bus where each user had their own system-on-a-card with an 8088 CPU. Our application wasn't client-server, each user had their own app and we had written our own code for network-based cooperative multitasking, as we called it in those early days.

Fifteen years later I was on a team that created a concurrency linter for Java. It inspected the behaviour of running J2EE servers and flagged runtime anti-patterns as concurrency smells to be investigated.

Everything felt so familiar, despite all of the tooling being complete different!