How to Dig Yourself Out of Technical Debt

If you don't have enough visibility into your systems to know when they're broken or not, that's technical debt you'v got to dig yourself out of. Remind me of some old commercial systems, like taking a giant c s v file from a supplier and using that to up date the stock of what's available for sale on the web site? It might not be as visible as im plugging a switch and someone coming to you door ten minutes later. Well, if you can't see it, dodn't matter, from my understanding. F bat the time, i hear it's some application that's ceiving input via f t p.