Notation: A, B, C,... stand for the various registers in the arithmetical and control register units. C to D
indicates that the switching circuits connect the output of register C to the input register D;(D+A) to C
indicates that the output register of A is connected to the one input of the adding unit (the output of D is
permanently connected to the other input), and the output of the adder to register C. A numerical symbol n
in quotes (e.g., 'n' )stands for the source whose output is the number n in units of the least significant digit.