Business travelers carried information tools long before the first microprocessor appeared, and not all of the tools are obsolete. Consider time zone calculations. I have a fancy program on my laptop and in my PDA, but the timezone calculator I use most often is an antique cardboard circular calculator freebie from PanAm that I found in an antique shop back in the 1980s.
It is better because it is always on, and never needs batteries replaced. It is light and takes up no space. Best of all, it’s analog nature gives me an instant sense of what time it is where on the entire planet. It is the essence of simplicity — and it will last decades longer than any other timezone tool I use today.