1. A method of translating subject program code executable by a subject processor into target program code executable by a target processor, said method comprising the steps of: (a) dividing the subject code into a plurality of subject code units; (b) translating one or more of the subject code units into one or more target code units via an intermediate representation; and (c) executing the target code units on the target processor; wherein the step (b) comprises (b1) identifying at least one of the subject code units as having a corresponding native code unit, wherein the native code unit is executable natively by the target processor, and (b2) identifying the native code unit which corresponds to the identified subject code unit; wherein the steps (b1) and (b2) are performed by encountering an external call command as a translator-specific instruction interpreted as an illegal instruction by the subject processor during translation of the subject code, decoding the external call command, and adding to the intermediate representation based on the external call command; and wherein the step (c) comprises executing the corresponding native code unit instead of executing a translated version of the identified subject code unit.