Bootable packet written re-writable optical disc and methods...

Electrical computers and digital processing systems: support – Digital data processing system initialization or configuration – Loading initialization program

Reexamination Certificate

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Details

C711S004000

Reexamination Certificate

active

06631468

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to optical storage media, and more particularly to methods and computer readable media for writing and reading to and from compact disc (CD) media.
2. Description of the Related Art
In recent years, compact disc (CD) recording technology has made substantial advancements that have enabled casual computer users to record all types of digital data to the CD media. As is well known, there are several types of CD media recording standards and associated media. For example, ISO-9660 (also known as ECMA-119) provides a file system for CD-ROMs. Specifically, the ISO 9660 provides a standard specifying how data shall be structured on a CD-ROM. Most platforms such as Microsoft Windows® and DOS® can read CD-ROM discs conforming to the ISO 9660.
However, the ISO 9660 standard does not provide means for changing or adding data on CD-ROMs. To overcome such limitations, the OSTA Universal Disk Format (UDF) has been created to implement ISO-13346 (also known as ECMA-167). Whereas ISO-13346 is a broad, general standard for storing information on any medium, the UDF specifically provides a standard for storing data not only on CD-ROMs but also on recordable and re-writable optical discs such as CD-Recordable (CD-R) and CD-Re-writable (CD-RW) as well as DVDs. Writing data in accordance with the UDF standard provides great flexibility in terms of transferring data between a CD medium and other storage devices, such as hard disks and floppy disks.
The CD-R and CD-RW discs differ in the manner data can be written. Specifically, CD-R disc is a write once media where data can be recorded only once over a single session or during multiple sessions. This is because the data that is digitally written to the CD-R causes a permanent change in the properties of the CD-R. This change in property is often referred to as the “burning” of data onto the CD.
On the other hand, data can be written and rewritten on a CD-RW disc much like a hard disk or a floppy disk. That is, data may be written to the CD-RW in fixed packet sizes and then erased and recorded again repeatedly. This is because the CD-RW, unlike CD-R, performs recording by making use of phase change materials in its recording layer. When the phase change material is irradiated by a laser beam, the data can be erased (crystal phase) and recorded (amorphous phase). Then, by way of differences in the reflectivity of either the crystal phase or amorphous phase, the data stored on the media can be read. However, data recorded on CD-RW media is typically not readable by standard CD-ROM drives.
For writing to re-writable optical media such as CD-RW discs, the UDF standard provides writing in “incremental packet mode,” which is well known and described in detail in UDF standards such as UDF 1.5 and 2.0, which are incorporated herein by reference. In the incremental packet mode, data is written in units of packets. The writing of data in units of small packets provides a more efficient means for writing data onto CD-RW discs. For example, before the implementation of incremental packet mode, if a data stream is interrupted while writing the data to a CD-RW disc, for example, the disc was no longer usable. In incremental packet mode writing, however, if a data stream is interrupted while writing fixed data packet to the CD-RW disc, only the interrupted packet becomes useless. In this case, new packets may be written after the interrupted packet such that the disc still contains useful data.
In general, optical discs are substantially cheaper than other mass storage media such as hard disk drives of comparable size. As a result, the optical discs are being widely used to store data for a variety of purposes. For example, the CD-RW discs are frequently used to backup hard one or more disk drives in a computer system. Additionally, the CD-RW media may be used to store custom software for distribution. The data stored in the CD-RW media may then be restored or installed on a computer system.
Restoring or installing data from optical media, however, often requires the use of a separate boot disk such as a floppy disk. For example, to restore data in a disaster recovery situation generally requires the user to insert a boot floppy disk to load an operating system before accessing the optical discs. Also, installing a custom software from a CD-RW disc often requires booting up the computer system by inserting a boot disk.
One prior art standard called “El Torito” defines a specification for a bootable CD-ROM format and is available from Phoenix Technologies and IBM. Specifically, the El Torito standard, also known as “CD/OS,” specifies a bootable CD-ROM format that allows a computer system to boot up from a CD-ROM, which conforms to the El Torito standard. Thus, a separate floppy boot disk is not required. The El Torito standard is well known in the art and is incorporated herein by reference.
Unfortunately, however, the El Torito standard does not provide a solution for booting up from a CD-RW media that conform with the UDF standard. In particular, the El Torito standard is not applicable to re-writable CD-RW discs that are written using incremental fixed packet writing mode. Instead, the El Torito specification is directed to providing a bootable CD-ROM only.
Additionally, CD-R discs are written using sequential writing methods such as track-at-once, session-at-once, disc-at-once, variable packet length writing, etc. In contrast, the conventional CD-RW discs can also be written using fixed length packets in addition to the various methods used for writing to the CD-R discs. This is because the CD-RW discs allows individual packets to be re-written in comparison with other methods where only complete tracks can be re-written.
FIG. 1A
shows a physical layout of an exemplary CD-RW disc
100
. In the CD-RW disc, a plurality of usable blocks
102
and link blocks
104
are laid out in sequence. Each of the usable blocks
102
and link blocks
104
are typically of fixed lengths. For example, each of the usable blocks
102
in which data may be written typically includes a fixed number of blocks such as 32 blocks. On the other hand, each of the link blocks
104
represents a slack space in which user data is not written and typically includes 7 blocks.
As is well known, although the link blocks
104
do not contain user data, they provide information (e.g., synchronization data, control data, etc.) necessary for proper reading of the CD-RW disc
100
. Individual blocks in the usable and link blocks
102
and
104
generally include 2,048 bytes or 2 Kbytes, respectively.
In this configuration, the first usable block
102
includes 32 blocks from block B
0
to block B
31
. Then, a link block
104
of seven blocks from block B
32
to B
38
follows. Following this link block
104
is another usable block
102
having blocks B
39
to B
70
and so on. In this manner, each of the usable blocks
102
represent a data space into which a fixed packet of data can be written.
Currently, two types of CD-RW devices are being widely used in the market: mode
1
and mode
2
devices. Mode
2
devices simply map out the bad blocks, i.e., link blocks
102
, as their occurrence is deterministic.
FIG. 1B
illustrates a schematic diagram of a CD-RW disc
100
A as seen by a mode
2
device. In this diagram, the mode
2
device skips the link blocks
104
. By thus skipping the link blocks
104
, the mode
2
devices reads the blocks in the usable data blocks
102
in sequence as if no link block existed. For example, the first block B
32
in the second usable data block
102
is treated as the next block of the block B
31
in the first usable data block
102
. In this manner, the mode
2
devices read only usable data.
In contrast, mode
1
devices read every block in a CD-RW disc including both the usable data blocks
102
and link blocks
104
.
FIG. 1C
shows a schematic diagram of a CD-RW disc
100
B as seen by a mode
1
device. As shown, the mode
1
device reads every block in the usable data and

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