Subroutine calls The processor does not have standard subroutine CALL immediate and RET instructions, though they can be emulated.

Similarly, loading a new constant into a register (such as a new address for a subroutine jump, or the address of a data variable) also involves four instructions (two load immediate, LDI, instructions, one for each half of the constant, each one followed by a Put instruction to the register, PHI and PLO).