Editing Shift register (section)

=== Data processing ===
In early computers, shift registers were used to handle data processing: two numbers to be added were stored in two shift registers and clocked out into an [[Arithmetic logic unit|arithmetic and logic unit (ALU)]] with the result being fed back to the input of one of the shift registers (the accumulator), which was one bit longer, since binary addition can only result in an answer that has the same size or is one bit longer.