Method and apparatus for dynamic load of an ABIOS device support layer in a computer system

An apparatus for loading an operational interface used in the operation of a personal computer system containing a system processor, a non-volatile memory, a volatile memory, and a direct access storage device;

• said operational interface comprising discretely separate first and second interface portions having different memory addressing capabilities;
• said first interface portion being required for completing a preliminary initialization of said system, and both said first and second interface portions being useful for enabling said system to perform applications defined by application programs;
• said non-volatile memory storing said first interface portion of said operational interface and a request indicator for indicating whether said second interface portion of the operational interface is required after completion of said preliminary initialization of said system;
• said direct access storage device storing said second interface portion of the operational interface;
• said apparatus comprising:
• means formed by said system processor and said first interface portion of said operational interface, during performance of said preliminary initialization of said system, for storing an image of said first interface portion of the operational interface in a predetermined part of said volatile memory;
• means formed by said system processor and said first interface portion, at completion of said preliminary initialization, for determining whether said computer system requires the second interface portion of the operational interface for continued operation of said system;
• determination means for determining whether said second interface portion of the operational interface is required;
• means responsive to said determination means for loading said second portion of the operational interface from said direct access storage device into said volatile memory if said second interface portion is required and for permitting continued operation of said system without loading said second portion if said second interface portion is not required.

A personal computer system compatible with application programs and operating system software, the personal computer system comprising:

• a microprocessor electrically coupled to a data bus;
• said microprocessor operating in different first and second modes;
• said microprocessor having access to first and second logical memory address spaces when operating respectively in said first and second modes;
• wherein said second logical address space contains and is larger than said first logical address space;
• said microprocessor operating initially in said first mode when it is powered up;
• non-volatile memory electrically coupled to the data bus, said non-volatile memory storing a first portion of operating system microcode used by said microprocessor only when it is operating in said first mode;
• a direct access storage device electrically coupled to the data bus for storing a second portion of operating system microcode;
• said second microcode enabling said system to handle applications requiring access to any of said regions;
• volatile memory electrically coupled to the data bus, said volatile memory storing a linking microcode for use by said microprocessor in effecting an initial transition from said first mode to said second mode;
• a memory controller electrically coupled to said microprocessor, said volatile memory and said non-volatile memory, said memory controller regulating communications between said volatile memory, said non-volatile memory and said microprocessor;
• said memory controller translating logical addresses associated with said logical address spaces into physical addresses associated with physical storage locations in said volatile and non-volatile memories;
• and
• linking means for linking said microprocessor to said second portion of operating system microcode during the initial transition of said microprocessor between said first and second modes, said linking means providing a logical address pointer indicating a starting location in said second logical address space;
• said pointer being used by said memory controller for locating said second portion of the operating system microcode in physical address locations of said volatile and non-volatile memories;
• said linking means enabling said microprocessor to access said second portion of the operating system microcode when first needed by said microprocessor to effect a transition from said first mode to said second mode.