You can still do things the old way. My second computer was an analog computer (the first was a Geniac):
[From the favorite catalog of my youth, the Edmund Scientific catalog. “[T]he Edmund catalog was virtually a Whole Earth Catalog for items related to scientific fields,” according to Wikipedia.] Those analog computer principles still apply today. (You can see how it worked in this Popular Electronics article.) I moved up to a slide rule as Gary Mintchell and I kidded back and forth recently.
The old ways still work, but… I’d much rather use my laptop computer than my slide rule.
In industrial automation, the old way is hard wiring every device. You can still do things the old way. But there is no reason to live in the past. Leave behind your slide rule and hard wiring and start using a computer and a fieldbus. PROFIBUS and PROFINET are the best fieldbuses to use (IMHO). And you can learn more about them at our free one-day training classes. Next up: next Tuesday in Davenport, IA for PROFIBUS and next Thursday in Boston for PROFINET. Look for Manny in Iowa and Mike and me in Boston. Leave the past behind and move at least up to 1999 and use PROFIBUS or up to today and use PROFIBUS and PROFINET. Hard wiring is more expensive to install and more expensive to troubleshoot. Leave the past behind. The old ways still work, but…