The present invention provides a computer system with random access memory at power up and a method for providing random access memory for use by the processor during initialization of the dynamic random access memory. A static random access memory unit is provided and coupled to the processor. It is assigned memory locations which overlay a portion of read only memory address space. BIOS code and selection logic provide signals to select either the read only memory or the static random access memory so that initialization code has sufficient random access memory to operate efficiently while it initializes the dynamic random access memory.