1. A computer system using non-volatile memory in lieu of random access memory, said computer system comprising: a bus; a processor coupled to said bus; and a non-volatile main memory coupled to said bus, said non-volatile main memory for storing operating system software, application software and data used by said processor when said computer system is operating after bootup; wherein said operating system software and said application software are executed by said processor while remaining resident in said non-volatile main memory; and wherein operating system software and application software used by said computer system after bootup are retained in an executable state within said non-volatile main memory when said computer system is powered off.