These mainframe COUs are really cool. But I still don’t feel like I understand where they make sense. I’ve heard they are used in finance, but what does that mean? High frequency trading? Processing credit card payments? Managing bank balances? I’ve always thought of mainframes as batch / offline systems, but this sounds much more online and low latency.
Transaction processing was basically invented on mainframes. High-throughput, high-volume, low-latency. I'm not sure about high-frequency trading, but in article nxobject linked above they say ~70% of financial transactions are processed on mainframes. So credit card transactions, bank transactions. Historically, things like airline reservations were also done on mainframes.
