Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output command process
Reexamination Certificate
1999-12-09
2001-09-04
Auve, Glenn A. (Department: 2181)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output command process
C710S110000
Reexamination Certificate
active
06286057
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an arrangement for and method of allowing a computer controlled system having a host computer and system Random Access Memory (RAM) to communicate with a data storage device connected to the computer controlled system using a bus which allows bus-initiated bus-mastering. More particularly the present invention relates to storing operating data and code for controlling the operation of the data storage device in the system RAM for use by the host computer and/or the data storage device.
As used herein, it is to be understood that the terms computer controlled system or computer system refers to any system which includes: a host computer arrangement or a microprocessor for controlling the operation of the system. It is also to be understood that the term System RAM refers to any memory used by the host computer or microprocessor for its operation. The computer controlled system may include consumer electronics, appliances, or any other computer controlled device as well as general purpose computers such as personal computers and computer servers. It should also be understood that the terms data storage device or storage device are intended to include hard disk drives, CD drives, floppy disk drives, removable hard disk drives, and other storage devices including other optical, magnetic opto-magnetic, and any other mass storage peripheral devices. These other storage devices also include devices such as digital video disk devices and flash memory which are currently being developed for use as storage devices for various types of computer systems. Also, as used herein, the phrases operating data and code or operating data/code are intended to refer to all of the various data and code that is required in order to operate the storage device.
Storage devices of all types share certain characteristics including an arrangement to uniquely address each addressable unit of the data on the media in which data is stored, an arrangement to control the device, and an arrangement to transport the data from the device to the system to which the device is connected. Hard disk drives are among the oldest and most popular of storage devices and have the longest history within computer systems. While much of the following discussion specifically relates to hard disk drives, it is to be understood that the principles of data addressing, device control, and data transport are not unique to hard disk drives and relate generally to all types of storage devices.
During the development of the personal computer industry, the typical arrangements for operating a hard disk drive connected to a host computer have gone through a series of evolutions. When the personal computer was first being developed, it was assumed that hard disk drives would be divided into cylinders, heads and sectors which would clearly define each data sector in which information could be stored on the hard disk drive. The DOS operating system defined a multiple byte, bit significant command structure with organizational limits of 1024 cylinders, 64 heads, and 64 sectors which corresponded to a total of 4,194,304 data sectors. The system BIOS, or a utility program used by this early computer system, was used to store any defective data sectors of the hard drive. These defective data sectors were required to be known by the system when the drive was formatted for use by the system. The system would not allow these defective data sectors to be used during the operation of the system. Therefore, only known good data sectors were used to store data and the actual cylinder head, and sector (CHS) on which the data was stored on the hard disk drive corresponded to the CHS data addressing information used by the operating system running the host computer.
In the early stages of development, the system BIOS also contained information on all of the disk drives which could be used with the system. As the number of drives available grew this approach became more and more difficult. The solution was to create user defined configuration information which could be used by the system.
These early approaches allowed the operating system to communicate with the disk drive using a relatively simple system BIOS which did not need to perform any translation of the CHS data address information. When the operating system of these early systems made a read/write request through the system BIOS, the system BIOS would simply pass the CHS address information on to the disk drive without having to translate the address information into some other format. Also, the disk drive was relatively simple in that it did not require any complex disk drive firmware as part of the disk drive to provide a translation function or handle the problem of keeping track of the defective data sectors since these functions were provided by the system.
The disk drive industry independently developed its own interface standards or limits known as Integrated Device Electronics (IDE) which also included a command structure. These IDE standards imposed limits which were different from the limits imposed by the operating system and system BIOS. The IDE command structure limits were set at 65,535 cylinders, 16 heads, and 256 sectors which provided a total of 268,431,360 data sectors. Since both standards utilized the same CHS addressing structure, the overall system limits were dictated by the lowest common bits for each field for the cylinders, heads, and sectors. This resulted in a combined limit of 1024 cylinders, 16 heads, and 64 sectors for a total of 1,048,576 data sectors. Although the combination of these two different limits did not initially create a problem by overly limiting the total data storage capacity of the disk drive, the demand for larger and larger capacity disk drives did eventually create a desire to offer drives which provided more sectors than were available according to the combination of these two limits.
To compensate for the combined limits, translation software was developed to translate from the operating system limits to the IDE drive limits. This software was provided in the form of either translating system BIOS or boot overlay translating BIOS software. The translation software allowed the operating system to use the entire theoretical number of data sectors, which the operating system limits allowed by translating from an operating system based CHS address to a disk drive based CHS address. However, each time a read/write request was made by the operating system, the translator had to translate the operating system's theoretical CHS address information (based on the DOS operating system standards) into logical CHS address information used by the disk drive (based on the disk drive industry standards). This translation required additional processing time slowing down the system but it increased the number of available data sectors back to the limits imposed by the operating system.
Technical developments in the disk drive industry further complicated the task of interfacing the hard disk drive with the host computer by making the hard disk drives more complex. The first additional development was that the hard disk drive industry being defining each data sector according to cylinders, heads, sectors, and zones. The zones of the disk drive correspond to different groups of cylinders of the disks with each of the zones having data stored at different frequencies in order to more efficiently use the data storing density of the disks. For example, the outer cylinders, which correspond to a first zone, may be read and written at a first frequency. The middle cylinders making up a second zone may be read/written at a second slower frequency. And finally, the inner cylinders, associated with a third zone, may be read and written at a third even slower frequency.
Although the use of zones increased the storage capacity of a given hard disk drive, it also further increased the complexity of the disk drive firmware and disk drive operating data required to control the disk drive. These new,
Cornaby Stephen R.
Harmer Tracy D.
Auve Glenn A.
Brady W. James
Swayze, Jr. W. Daniel
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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