the good old days of mainframe computers

[Don Shepherd]

(09-22-2021 05:11 PM)bbergman Wrote:  Mainframe life was very different, but I do think it (appropriately) contributed to the maturity of software development over time. Yes, it was a closed system, but that was mainly an asset protection factor. It wasn't like you could buy a new laptop for $500; this was a piece of equipment that cost $50k-$100k per CPU. You had to protect it.

When I was learning Fortran in high school, we punched the cards in class and sent the stack out for processing. 3-4 days later, we got our cards back, plus a green+white 132 column printout from the line printer that showed our run results. It only took ONE buggy run to teach us the value in hand checking our code before sending it out. Within a couple of weeks of the start of the semester, everyone was going over their code, running it on "paper", checking for boundary conditions, doing unit testing, pair programming, and more. No one wanted to send in a stack of cards and have them come back next week with a failure on Line 1. These practices all translated into a maturing software development mindset that is still evidenced today. Maybe not all the same practices, but many of them are. It was an important step.

Bruce, we called that "desk checking" and our boss insisted that we do that. Yes, it took some time, but it invariably caught coding and logic errors that might not have been detected otherwise. Our US Census Bureau FORTRAN programs processed files with millions of records (one record per business establishment in the US) and reruns due to program errors would have been unacceptable.