The IBM Magnetic Drum Calculator Type 650 is an electronic calculator intermediate in speed, capacity and cost. It takes a logical position between the IBM Card Programmed Electronic Calculator and the IBM Electronic Data Processing Machines Type 701. It is a more powerful computing tool as required by those who have “outgrown” the Card Programmed Electronic Calculator. It is also a machine which may be used economically by those who are not as yet ready for a large scale computer such as the 701. It will serve not only to perform their required computing tasks, but it will also result in gaining valuable experience for later use of large scale equipment. The Magnetic Drum Calculator, through its stored program control, comprehensive order list, punched card input-output, self-checking and moderate memory capacity, gains the flexibility required of a computer which is to serve in both the commercial and scientific computing fields. Approximately 2000 tubes are used in the machine. They are the 5965, 6211, 12AY7, 6AL5, 2D21 and 5687. Types 6211, and 5965 are similar to the 12AV7. These are used because they meet special IBM acceptance tests.