Emulation of instructions that include non-contiguous specifiers is facilitated. A non-contiguous specifier specifies a resource of an instruction, such as a register, using multiple fields of the instruction. For example, multiple fields of the instruction (e.g., two fields) include bits that together designate a particular register to be used by the instruction. Non-contiguous specifiers of instructions defined in one computer system architecture are transformed to contiguous specifiers usable by instructions defined in another computer system architecture. The instructions defined in the another computer system architecture emulate the instructions defined for the one computer system architecture.