instruction code Push-Comp The instruction code 'Push-Comp' is an instruction code of the transsmt instruction set that pops a value off of the ?B? stack and pushes it onto the complement stack (i.e., the stack two over in sequence), in this case, the ?D? stack. This instruction code can be modified by one or two 'Nop' instruction codes, which specify the source and the destination stacks, respectively.