Ask HN: What was software development in 80s, 90s, 2000's like?

Nowadays we have software shifting to the Web, Agile/Scrum management, automatic test frameworks like Cypress, hot-reload tools for fast checking on local environment. But what it was like to be software dev in earlier eras?

1) Were there any kind of hot-reloading? If you didn't have latter, then how did you check correctness of code before "deploying" it? I worked with Rust backend some time, they write unit/integration tests before deploying even to test server. It's most about monetary calculations and account operations, ok. But what about testing video games, frontend applications? It's more about displaying info, graphics and user interactions so writing automated tests for them seems more complex and you need to check correctness of code ASAP. Especially interesting part is about graphics rendering: how long it took to check that specific formula, algorithm draws some 3D effect correctly? Could this ever be auto-tested?

2) How did managers control work process, checked that some work is done?

3) What was technical interviews like? Now mostly they're not about algorithmic/mathematical problems, but about tricky parts of some programming language(s), tools like PostgreSQL/Redis. And just soothy talk about development experience.