Agree on all except the last sentence: As I understand it, on the more modern mainframes there's one big ole SQL database in normal form with joins and transact

Agree on all except the last sentence: As I understand it, on the more modern mainframes there's one big ole SQL database in normal form with joins and transactions, but on others there's a huge bunch of applications (usually written in COBOL) that handle data in fixed-field files, predating normal form, joins, and transactions.