The IBM 1401 Computer was one of the first computer systems I worked on.
Among other things, it was the computer used at that time by the U.S. Army computer-programming school which I attended in the fall of 1968. We were told that whoever finished first in the class would have their choice of next duty stations. I was the one who came in first and chose the Presidio of San Francisco as the closest option to my pre-army home (Los Angeles).
It was in San Francisco that I met and married my wife. I told this story recently to my younger daughter explaining to her that if it weren’t for the IBM 1401 she wouldn’t be here.
The Computer History Museum just recently unveiled a reconstructed IBM 1401. I attended that unveiling, and shot some video which you can see here.
More details about the 1401 and my army experience with it can be found in my computer memoirs.
I have long wondered how the 1401 did decimal arithmetic. I knew from my experience that the related IBM 1620, upon which I also worked, did decimal arithmetic from a table lookup, the tables being stored in main memory. I equally knew that the 1401 had no such tables.
I have come across an article that explains how it was done (in hardware logic, not by table lookup): http://www.righto.com/2015/10/qui-binary-arithmetic-how-1960s-ibm.html