Can't understand what multiplexers do in CPU datapath
G multiplexer: Selects the second argument to the ALU. Possible values are another register's value or the immediate value of the instruction.

L multiplexer: Selects the value to write into the destination register. Possible values are the value of the addressed RAM register or the result from the ALU.

H shifter: Multiplies the immediate value of the instruction by 4, as the PC needs.