Each of the values after A=, B= and C= encode a 3-bit binary number which is inputted to the appropriate 3x8 decoder that selects which register will be gated onto which bus. If A=2, then the value 0010 or 2 will be inputted to the A decoder, causing the contents of register 2, which is the PC register, to be copied onto the A bus. The F= value denotes the ALU function, according to the table on page 3, only expressed in decimal instead of binary. Thus F=5 means the F wires contain 101, which is an addition.

RISC computers try to make each cycle of the main data path be a machine instruction, so they usually disallow operand fetches from memory, instead using more registers. It is not uncommon for a RISC machine to have hundreds of registers.