Obviousness

Obviousness Analysis of US Patent 6085318 Under 35 U.S.C. § 103

This analysis assesses the obviousness of US Patent 6085318, titled "Computer system capable of booting from CD-ROM and tape," under 35 U.S.C. § 103, based on the prior art described within the patent's "BACKGROUND OF THE INVENTION" section. The priority date for this patent is September 10, 1993.

Identification of Prior Art and Motivation

The patent itself describes the state of the art at the time of the invention and explicitly states the problems it aims to solve, providing significant motivation for a person having ordinary skill in the art (PHOSITA) to combine known elements.

Elements of Prior Art (as described in US6085318's background):

1. Conventional Computer Booting: Personal computers conventionally boot from various media, such as floppy disk drives or hard disk drives, and in some cases, from external locations (e.g., networks). The boot order is typically a fixed arrangement (e.g., external, floppy, hard drive). [cite: It has been conventional for personal computers to boot from various media, for example a floppy disk drive or a hard disk drive. Generally, the order of trying the various sources is a fixed arrangement, such as the external boot location, the floppy drive and finally the first hard drive.]
2. Increasing Software Size: Diagnostic, configuration (e.g., EISA CONFIG), and application programs were continually increasing in size, often exceeding the capacity of a single floppy disk and requiring many diskettes. [cite: One trend in the personal computer field is the ever increasing size of programs, including diagnostic programs, configuration programs and application programs. The third problem is the ever growing size of operating system and application programs. In many cases 10 to 20 1.44 MB floppy diskettes are required to contain the copy of the program to be loaded onto the computer's hard disk for use thereafter.] This created a "need for a growing number of floppy disks which are quite cumbersome, expensive, bulky and subject to accidental erasure." [cite: All of these trends have resulted in a need for a growing number of floppy disks which are quite cumbersome, expensive, bulky and subject to accidental erasure.]
3. CD-ROMs as High-Capacity Media: The use of CD-ROMs to contain these large programs was an "immediate thought" for solving the capacity problem. [cite: The first thought that would immediately come to mind would be the use of CD-ROMs to contain these programs.]
4. ISO 9660 Standard for CD-ROMs: The International Standards Organization (ISO) had developed the ISO 9660 standard for data on CD-ROMs. This standard defined a "system area," a "primary volume descriptor," an "ISO defined boot record," "volume partition descriptors," and a "volume descriptor terminator," followed by the "primary volume space" which could include "floppy images" (e.g., 1.44 MB and 1.2 MB floppy images). [cite: To this end, the International Standards Organization (ISO) has developed standards for data on CD-ROMs. This includes an area reserved for the manufacturer; a primary volume descriptor, which is a block which indicates the size of the actual data stored on the CD-ROM drive; an ISO defined boot record; several ISO defined volume partition descriptors; and a volume descriptor terminator. The volume descriptor terminator is followed by the primary volume space, which includes any volume partitions, such as the main volume, and any additional volumes, such as a 1.44 MB floppy image and a 1.2 MB floppy image.]
5. Known Problem with ISO 9660 Booting: Despite the ISO standard, there was "no manufacturing support for preparing a bootable ISO CD-ROM and there [was] no software which recognizes an ISO-standard bootable CD-ROM." Crucially, "systems [were] not available to write data to the various locations specified by the ISO for the boot record, the various volume partition descriptors, and the volume descriptor terminator. Available systems [could] only write to the system area, the primary volume descriptor and the primary volume space." [cite: While this would appear to solve the problem, it does not. The reason is that there is no manufacturing support for preparing a bootable ISO CD-ROM and there is no software which recognizes an ISO-standard bootable CD-ROM. Systems are not available to write data to the various locations specified by the ISO for the boot record, the various volume partition descriptors, and the volume descriptor terminator. Available systems can only write to the system area, the primary volume descriptor and the primary volume space.]
6. Desire for BIOS Compatibility: It was "desirable to limit any changes made to incorporate booting from a CD-ROM drive so that the various conventional routines, commonly BIOS interrupts, which are utilized in the computer do not need to be redefined but can continue to remain compatible with present functions while being extended for new capabilities." [cite: It is also desirable to limit any changes made to incorporate booting from a CD-ROM drive so that the various conventional routines, commonly BIOS interrupts, which are utilized in the computer do not need to be redefined but can continue to remain compatible with present functions while being extended for new capabilities.] This implies that techniques like BIOS interrupt hooking/redirection were known for extending functionality while maintaining compatibility.
7. SCSI Devices: The patent describes a computer system with a SCSI subsystem including hard drives, CD-ROM drives, and tape drives, indicating SCSI technology was known for mass storage. [cite: A SCSI bus 78 is provided from the SCSI port 76 and has connected to it a SCSI hard drive 80, a SCSI CD-ROM drive 82 and a SCSI tape drive 84.]

Motivation for a PHOSITA:

A PHOSITA at the time (September 1993) would be highly motivated to enable booting from high-capacity media like CD-ROMs and tape drives for software distribution and system recovery, given the limitations of floppy disks. The existing ISO 9660 standard indicated a clear desire for bootable CD-ROMs but presented a practical implementation problem due to manufacturing tool limitations. The PHOSITA would seek a solution that circumvented these limitations while maintaining compatibility with established PC booting mechanisms (e.g., BIOS INT 13).

Obviousness Combinations and Rationale

The claims of US6085318, particularly Claim 1 (system), Claim 14 (method of booting with disk image), and Claim 21 (method with emulation), would have been obvious to a PHOSITA by combining the known prior art elements as follows:

Combination: Prior Art 1 (Conventional PC Booting) + Prior Art 2 (Increasing Software Size) + Prior Art 3 (CD-ROMs as High-Capacity Media) + Prior Art 4 (ISO 9660 Standard) + Prior Art 5 (ISO 9660 Booting Problem) + Prior Art 6 (BIOS Compatibility) + Prior Art 7 (SCSI Devices)

Rationale for Obviousness:

1. Placement of Boot Record (Addressing Claim 1 & 30): The primary challenge identified by the patent was the inability to write to the ISO-designated boot record location on a CD-ROM, despite the ISO standard defining a boot record and its purpose. However, the "system area" of an ISO 9660 CD-ROM was known to be "readily writable by the systems used in developing CD-ROMs." [cite: The system area is readily writable by the systems used in developing CD-ROMs and so this boot record location can be utilized.] A PHOSITA, faced with the need to create a bootable CD-ROM and knowing the limitations of writing to the specific ISO boot record sector, would find it obvious to place an ISO-compliant boot record (containing identification and information for accessing an image) within the writable system area (e.g., sector 0 or 15) to achieve bootability using existing mastering tools. This is a simple design choice to overcome a known manufacturing limitation while adhering to the functional intent of the ISO standard.

2. Floppy Disk Image and Loading (Addressing Claim 1, 14, 30): The ISO 9660 standard already contemplated "floppy images" (e.g., 1.44 MB and 1.2 MB images) within the "primary volume space." [cite: The volume descriptor terminator is followed by the primary volume space, which includes any volume partitions, such as the main volume, and any additional volumes, such as a 1.44 MB floppy image and a 1.2 MB floppy image.] Booting from a floppy disk image was a known concept in disk-based booting. Once a boot record is located on the CD-ROM, it is an obvious step for boot code within this record to determine the type of emulated floppy image needed (e.g., 1.44 MB vs. 1.2 MB, based on the system's detected floppy drive type) and its location (e.g., at the end of the primary volume space, a writable area), then load the boot code from that image. This is a logical extension of existing boot loader functionality adapted for a CD-ROM-based image.

3. BIOS Interrupt Redirection/Emulation (Addressing Claim 1, 14, 21): The patent explicitly states the desire for CD-ROM booting to maintain compatibility with "conventional routines, commonly BIOS interrupts," like INT 13, without redefinition. [cite: It is also desirable to limit any changes made to incorporate booting from a CD-ROM drive so that the various conventional routines, commonly BIOS interrupts, which are utilized in the computer do not need to be redefined but can continue to remain compatible with present functions while being extended for new capabilities.] The technique of "hooking" or redirecting BIOS interrupts was a well-known programming practice in PC system development to intercept standard I/O calls and reroute them to a different device or a simulated region of memory, thereby achieving compatibility with legacy software or providing extended functionality. Therefore, a PHOSITA would find it obvious to:

   • Intercept INT 13 calls (typically used for floppy disk I/O).
   • During the boot process from a CD-ROM, redirect these calls to read data from the emulated floppy image on the CD-ROM via the SCSI controller (Prior Art 7).
   • Once the core operating system and native CD-ROM drivers (e.g., MSCDEX for DOS, mentioned in the patent) are loaded, cease the redirection and restore the original INT 13 vector, allowing the physical floppy drive to be "fully utilized" [cite: and clears the redirection value in the EBDA so that references to the floppy drive are no longer redirected and the floppy drive can be fully utilized.] and the CD-ROM to be accessed in its native mode. This sequence directly addresses the steps of configuring, issuing a first type of command, booting, reconfiguring, and issuing different command types as claimed in Claim 21.

4. Extension to Tape Drives (Addressing Claim 1, 14, 21, 26): The patent itself notes, "A similar structure can be developed for a tape, so that tape can also be the boot media." [cite: A similar structure can be developed for a tape, so that tape can also be the boot media.] Given that tape drives are also SCSI mass storage devices (Prior Art 7) and present similar high-capacity advantages over floppy disks as CD-ROMs, extending the CD-ROM booting mechanism (boot record, floppy image, BIOS redirection via SCSI) to a tape drive would be a straightforward and obvious engineering generalization.

Conclusion

Considering the background art described within US6085318, a PHOSITA would have been motivated to use CD-ROMs and tape drives for booting due to the limitations of floppy disks for increasing software sizes. The existing ISO 9660 standard, despite its practical implementation flaws, provided a conceptual framework for bootable CD-ROMs and floppy emulation. Overcoming the ISO 9660 manufacturing limitations by placing the boot record in a writable system area, combined with the well-known technique of BIOS interrupt hooking/redirection to emulate a floppy drive during the initial boot sequence, would have been an obvious combination of known elements to achieve a predictable result: a computer system capable of booting from CD-ROMs and tape drives while maintaining compatibility with legacy software and hardware interfaces. Therefore, the claimed subject matter would have been obvious under 35 U.S.C. § 103.