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A Method to Circumvent the BIOS Option ROM Size Limitations

IP.com Disclosure Number: IPCOM000014993D
Original Publication Date: 2002-Mar-14
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Abstract

This publication provides idea of this invention is to provide a minimum sized Adapter "Option ROM" that can be loaded by PC BIOS into system Memory. This minimum sized "Option ROM" would only provide a basic interface to code running on the adapter, which would have more resources available to provide more functionality than can be handled in the limited "Option ROM" environment that we have in today's PCs.

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A Method to Circumvent the BIOS Option ROM Size Limitations

    This publication provides idea of this invention is to provide a minimum sized Adapter "Option ROM" that can be loaded by PC BIOS into system Memory. This minimum sized "Option ROM" would only provide a basic interface to code running on the adapter, which would have more resources available to provide more functionality than can be handled in the limited "Option ROM" environment that we have in today's PCs.

The following picture illustrates a typical AT Style personal Computer emphasizing the CPU, Real Mode Memory, Busses and Adapter.

The discussion that follows is concerned with the boot time initialization of the PC. When the PC is first turned on or reset, the first instructions that are executed are from the BIOS ROM. The BIOS is responsible for initializing the hardware facilities on the PC, loading the Operating System, and providing an interface between the Operating System and the hardware platform. During the initialization process, the BIOS will configure what is labelled as the "CPU Bus to Adapter Bus Bridge" in the diagram above and then query the Adapter Bus for any adapters. When the BIOS detects an adapter, it will determine whether the adapter contains an "Option ROM". The Option ROM contains object code which is provided by the adapter card vendor. This Option ROM serves to provide BIOS support for complex adapters such as video or disk controller adapters, that are too complex for the...