Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
1995-11-03
2002-05-21
Oberley, Alvin (Department: 2151)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C713S002000
Reexamination Certificate
active
06393492
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an arrangement for and method of operating a mass memory storage peripheral computer device, such as a hard disk drive, connected to a host computer using a peripheral bus in which relocatable Expansion Basic Input Output System (BIOS) location addresses are allowed. The computer has system Random Access Memory (RAM) and uses an operating system and system BIOS to operate the host computer. More particularly the present invention relates to a loadable device driver which is associated with the hard disk drive and which is loaded into the system RAM during the start-up of the computer system. The loadable device driver controls the operation of the hard disk drive in a way which does not require the system BIOS or any other protocol translation mechanism other than the loadable device driver to be provided between the hard disk drive and the operating system in order for the operating system to communicate with the hard disk drive.
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 which 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.
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 device driver, 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 65535 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 desire to offer drives which provided more sectors than were available according to the combination of these two limits.
To compensate for these 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 BIOS or boot overlay 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 system. The first additional development was that the hard disk drive industry began 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 inner 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 faster frequency, and the outer cylinders associated with a third zone may be read and written at a third even faster frequency. Although this development increase the storage capacity of a given hard disk drive, it also further increased the complexity of the overall system by requiring another translation from the system BIOS CHS address information to the actual cylinder, head, sector, and zone address information actually used by the disk drive.
In another development, the disk drive industry changed the way the cylinders, heads, and sectors were typically addressed. Initially, each data sector on the disk drive included an identification field containing the address of that field and including information on whether that sector was defective or not. These identification fields for each of the data sectors used a significant portion of the data storage space on the disk drive thereby reducing the amount of usable data storage space for a given disk drive. As more advanced disk drives having more sophisticated controllers became available, the need for an identification field associated with each data sector was eliminated thereby increasing the data storage capacity of a given disk drive. However, using this approach required the defect information identifying which sectors of the disk drive are defective to be stored in a different way.
In order to solve this problem, a defect list containing a list of all the defective data sectors on the disk drive is typically stored on the memory storage of the hard disk drive and loaded into a RAM memory buffer on the disk drive device during the initialization of the disk drive so that the list is available to the hard drive controller during the operation of the disk drive. This approach requires an even more complicated controller, more complicated disk drive firmware to operate the controller, and a larger RAM memory buffer than would otherwise be required so that the defect list may be stored in the memory buffer for use throughout the operat
Cornaby Stephen R.
Harmer Tracy D.
Brady W. James
Lao Sue
Oberley Alvin
Swayze, Jr. W. Daniel
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