Well, I didn't want to date myself that much, but, yes, I used a Keuffel & Esser model 68-1100 Deci-Lon slide rule, in the standard orange-brown leather belt-hanging case and, yes, I still have it in a place of honor on my desk, along with my mechanical drawing tools in their original blue velvet-lined leather case. Ah, the memories ... and I'm not talking about RAM, for once!
The best things in life aren't things ... but, a Pi comes pretty darned close!
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!