Data processor having bios packing compression/decompression architecture

Abstract

To increase the effective capacity of BIOS, an initial portion of the power on system reset (POST) code that is required to enable the system memory is stored in ROM in uncompressed form, and substantially the remaining portion of the BIOS code is stored in compressed form. Upon system initialization during a cold boot, the uncompressed portion of POST is executed from the ROM to enable the system memory, and then an image of the BIOS code is written to shadow memory. As BIOS code is needed during the remainder of the boot, the code is selectively decompressed from the shadow memory to another region of the system memory to which control is transferred. Variations based upon different boot scenarios are described.

Description

BACKGROUND OF THE INVENTION[0001] 1. Field of the Invention[0002] This invention relates generally to data processing, and more particularly, to storage and execution of BIOS code in a personal computer.[0003] 2. Description of Related Art[0004] All computers, such as the various models of personal computers, or PC's, produced by IBM, execute "operating system software" that instructs the PC on how to use other programs, termed "application software," such as word processing and spreadsheet programs.[0005] Examples of PC operating systems include MS-DOS and WINDOWS, manufactured by Microsoft Corporation, and IBM's OS / 2.[0006] Before a PC can run an operating system, it must load the operating system from a disk to the PC's working memory which is ordinarily random access semiconductor memory (RAM). This is carried out through a process known as "bootstrapping," or more simply, "booting" the PC. Booting occurs automatically when the PC is first turned on, a process called a "cold boo...

AI Technical Summary

Benefits of technology

This approach reduces boot time and maintains compatibility with existing PC architecture by enabling efficient decompression and execution of BIOS code under various boot scenarios, including cold and warm boots in real and protected modes, while accommodating increased BIOS requirements.

Problems solved by technology

In the absence of these files, the BIOS will generate an error message.

However, the size of the portion of the read only memory (ROM) resident in a PC for storing BIOS code is limited.

In view of the 128K boundary defined for BIOS, the existing BIOS ROM is insufficient in size to accommodate the necessary services (features and functions).

However, paging and other approaches that require an ROM memory of increased size are accompanied by additional hardware requirements, and hence, cost, and in some cases, system performance degradation.

These attempts have been limited, however, to compressing only the SETUP and, more recently, the video BIOS area.

But the remaining portions of the BIOS code have not been a candidate for compression, among other reasons because there has been no mechanism for compressing large blocks of BIOS including the POST component of the BIOS code, decompressing and then booting successfully.

More particularly, a problem is encountered when considering how to compress and thereafter decompress BIOS code upon system initialization.

Furthermore, decompression of BIOS from the ROM into the shadow memory is relatively slow, increasing the time required for bootstrapping.

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