Bootstrap

There is a load button and a selector switch on the machine, but they do just barely enough to get the process started. The rest in accomplished by a technique sometimes called the “bootstrap technique.” – Buchholz: The System Design of the IBM Type 701 Computer

Double length division

Division should be the inverse of multiplication. Since multiplying two full-word (35-bit) factors generates a double-length (70-bit) product in the accumulator and /MQ/ register, division has been similarly arranged to start with a double-length (70-bit) dividend stored in the accumulator and /MQ/ register. This appears to be an elementary piece of logic, and it is surprising that a double-length dividend has not been provided in other computers of this type.