1. A vehicle or engine diagnostic system, comprising: an interface for receiving a signal relating to a performance parameter of the vehicle or engine; a central processing unit, for performing a processing operation responsive to the signal; long term application program storage, for storing software applications utilized by the system to implement one or more testing or diagnostic functions; a non-volatile nano random access main memory (NNRAM) coupled to the central processing unit as main memory for use by the central processing unit; and programming for execution by the central processing unit stored in the NNRAM main memory, wherein execution of the programming directly from the NNRAM main memory causes the central processing unit to perform steps, comprising: (a) prioritizing a plurality of the software applications utilized by the system to implement one or more testing or diagnostic functions; (b) storing a selected one of the software applications as part of the programming from the long term application program storage into the NNRAM main memory, based on the prioritization; (c) booting the central processing unit to enable use of the programming including the selected software application directly from the NNRAM main memory; (d) modifying the prioritization of the software applications utilized by the system to implement one or more testing or diagnostic functions; (e) storing a different selected one of the software applications as part of modified programming from the long term application program storage into the NNRAM main memory, based on the modified prioritization; and (f) booting the central processing unit to enable use of the modified programming including the different selected software application directly from the NNRAM main memory.