Electrical computers and digital processing systems: support – Digital data processing system initialization or configuration – Loading initialization program
Reexamination Certificate
1999-01-20
2003-01-21
Butler, Dennis M. (Department: 2182)
Electrical computers and digital processing systems: support
Digital data processing system initialization or configuration
Loading initialization program
Reexamination Certificate
active
06510512
ABSTRACT:
BACKGROUND
1. Field
This field relates to computer software for execution of BIOS code from a secure, multitasking operating environment, such as Microsoft Windows NT™.
2. Description of the Related Art
Computer systems in general and International Business Machines (IBM) compatible personal computer systems in particular have attained widespread use for providing computer power to many segments of today's modern society. A personal computer system can usually be defined as a desk top, floor standing, or portable microcomputer that includes a system unit having a system processor and associated volatile and non-volatile memory, a display monitor, a keyboard, one or more diskette drives, a fixed disk storage device and an optional printer. One of the distinguishing characteristics of these systems is the use of a system board to electrically connect these components together. These personal computer systems are information handling systems which are designed primarily to give independent computing power to a single user (or a relatively small group of users in the case of personal computers which serve as computer server systems) and are inexpensively priced for purchase by individuals or small businesses. A personal computer system may also include one or a plurality of I/O devices (i.e. peripheral devices) which are coupled to the system processor and which perform specialized functions. Examples of I/O devices include modems, sound and video devices or specialized communication devices. Mass storage devices such as hard disks, CD-ROM drives and magneto-optical drives are also considered to be peripheral devices. Operating systems have evolved from single user, single task operating systems, such as MS-DOS (for Microsoft Disk Operating System), to single user, multitasking operating systems, such as Microsoft Windows NT™.
BIOS Use Under MS-DOS
MS-DOS uses BIOS (basic input/output system) to manage many basic operations of the system. During system initialization, or “boot,” a check is made of the hardware components before control is passed to a ROM BIOS boot program which typically checks the floppy drive (“drive A”) to see if it contains a formatted diskette. If drive A does not contain a formatted diskette, the ROM BIOS checks the fixed disk drive (“drive C”) to see if it is formatted. When a formatted disk is found, the ROM BIOS reads two hidden system files found on the disk—an input/output system file (IO.SYS or IBMBIO.COM) and a disk operating system file (MSDOS.SYS or IBMDOS.COM). The IO.SYS file is loaded into RAM and includes a system initialization routine (SYSINIT) that performs the remaining boot sequence. Part of the boot sequence includes loading MSDOS.SYS into RAM. MSDOS.SYS and the BIOS manage disk files, execute programs, and respond to hardware signals. Further along in the boot sequence, device drivers are loaded to control memory or hardware devices.
Under MS-DOS program files, BIOS, and device drivers cooperate in performing system and hardware functions. Machine specific information is often contained in the BIOS. This machine specific information includes the speed of the floppy drive and how the speed can be changed for a 3-mode floppy drive, whether the cache is turned on or off and how to turn the cache on or off, and many other machine specific pieces of information. Under MS-DOS, a program could simply execute the particular BIOS code to receive and set such machine specific information. However, as operating systems have evolved, more secure multitasking operating systems, such as Microsoft Windows NT™, are designed to prevent direct execution of BIOS code. While direct execution of BIOS code is desirable to provide a more stable multitasking environment where many programs simultaneously share system resources, the information stored in a system's BIOS is still needed and may still need to be executed from time to time. While Windows NT™ prevents execution of the BIOS, it does allow program files to read the BIOS information.
BIOS Use Under Windows NT™
Windows NT™ implements its security and protection capabilities by emulating system BIOS, thus preventing BIOS calls by high-level software programs. However, Windows NT™ is not able to emulate all BIOS calls which may be needed by the high-level software. Other ways have been developed to provide machine specific information on a secure operating system such as Windows NT™ without having the operating system actually execute the BIOS code.
One way an operating system program (or driver) can solve this problem is through a large branch table based on the hardware platform. The branch table could give the operating system program knowledge of every machine it is capable of supporting at the time the branch table is developed. A challenge of this method is that the branch table cannot be forward compatible with hardware developed after the branch table has been released.
A second way an operating system program can receive machine specific information is through implementing pseudo-code in the BIOS that the system is capable of interpreting. A pseudo-code approach allows the BIOS to handle requirements based on the requirements declared in the BIOS. A challenge to this approach, however, is that the pseudo-code and its corresponding interpreter must be robust enough to handle future hardware requirements developed after the pseudo-code and interpreter are released.
What is needed is a solution that allows execution of BIOS functions from a high-level software, especially in cases where Windows NT™ is unable to emulate the particular, often system specific, BIOS routines.
SUMMARY
To address the above-discussed deficiencies of the prior art, the present invention provides a computer system for executing BIOS code on a secure operating system. The computer system includes a processor, memory coupled to the processor, at least one nonvolatile storage device, such as a hard disk drive, a BIOS file stored on the nonvolatile storage device, and a computer program executable by the processor. The computer program is capable of locating BIOS code within the BIOS file and copying the BIOS code to an executable program file stored on the nonvolatile storage device which is executed by the processor. The present invention also provides a method of executing BIOS code on a secure operating system. The method locates the BIOS code within at least one BIOS file, copies the BIOS code to an executable file, and executes the resulting executable file on a processor.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations and omissions of detail. Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below.
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Waite et al., Soul of CP/M, 1983, pp. 279-322.
Baker & Botts L.L.P.
Butler Dennis M.
Dell Products L.P.
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