Chuck Fillerup and the IBM 650

One of the items in a recent donation to the Computer History Museum was an IBM 650 computer. IBM announced this machine in 1953, and it used a magnetic drum for memory instead of core.

My first job when I graduated from UCLA in 1965 was at IBM Service Bureau Corporation. My mentor there was Dr. Chuck Fillerup. Chuck taught me a lot about programming while we worked together on several projects.

Dr. Chuck Fillerup
Dr. Chuck Fillerup

Chuck told me many stories about how challenging it had been for him a few years earlier to program the IBM 650, since memory was actually a rotating drum. The way a program transferred control from one piece of code to another could have a big impact on performance, especially if it caused the program to have to wait too much for drum rotations. I thought of Chuck when I set my eyes on the 650 sitting in the Computer History Museum warehouse.

IBM 650 computer in the Computer History Museum collection
IBM 650 computer in the Computer History Museum collection