Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus expansion or extension
Reexamination Certificate
2000-02-29
2003-07-15
Ray, Gopal C. (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus expansion or extension
C710S302000, C710S303000, C710S306000, C711S102000, C711S112000, C709S241000, C713S300000
Reexamination Certificate
active
06594721
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
COMPUTER PROGRAM LISTING APPENDIX
A compact disc has been submitted to the U.S. Patent and Trademark Office containing a computer program listing appendix, which is incorporated by reference herein. The computer program listing appendix is contained in a text file named “Appendix.txt”. The compact disc is recorded in CD-R format, which is compatible with IBM PC-compatible computers and Apple Macintosh computers employing MS-Windows and Macintosh operating systems, respectively.
COPYRIGHT NOTICE
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to systems for enabling hot insertion and removal of peripheral devices from a computer bus. More particularly the present invention relates to an apparatus and method for implementing a system that allows device drivers to detect device changes occurring during hot docking and hot bay swapping. Still more particularly, the present invention relates to a system that can support hot bay swapping and hot docking for all IDE/ATAPI devices across all operating systems using a structured device driver architecture and reduced complexity Basic Input Output Subsystem (BIOS) firmware.
2. Description of the Prior Art
Many portable computer systems are based on the Intel 80x86 or Pentium series of microprocessors, or another compatible microprocessor, and are controlled by operating system software. In such systems, additional peripheral devices such as hard disk drives, CD-ROM drives, DVD drives, CD-RW (re-writable) drives, tape backup drives, ZIP drives, LS-120 drives and so forth are often added and removed by the user.
For example, an extra hard disk may be added to increase storage capacity. Generically referred to as “Plug and Play” (PnP), the addition of the hard disk is typically performed by powering-off the computer and inserting the extra hard disk into a bay designed to accept such a device. A bay is an external connector located on the housing of the portable computer that accepts a peripheral device connector. The bay connects to a bus such as an ISA (Industry Standard Architecture), EISA (Extended Industry Standard Architecture), or PCI (Peripheral Component Interconnect) bus linking the device to other components in the system. When the system is subsequently powered-on and “reboots”, the presence of the new hard disk device is detected on the bus and the operating system configures itself and the new device for proper operation with one another and application programs. To remove the hard disk, the power is turned-off and the device is removed from the bay. When the operating system subsequently reboots, no configuration for the device takes place due to the absence. (i.e., removal) of the device on the bus and the system will not permit communication with the absent device.
During device configuration, the system “enumerates” each device detected on each bus at system start-up. The enumeration process assigns a unique address or number to each device in order to properly access that device. The system also loads device driver software into memory for each device detected, if a driver is not already present. Device drivers provide the required instructions for proper device operation with the operating system and the applications that access the device.
In Plug and Play operating systems as described above, enumeration of new peripheral devices is supported by the operating system and Basic Input Output Subsystem (BIOS) firmware. Peripheral device drivers written for PnP operating systems will not function without this operating system and BIOS support. In some computer systems, BIOS firmware does not include Plug and Play support and therefore a PnP operating system alone will not be able to recognize PnP devices. Under such operating systems, the user must manually disable all unused devices and corresponding IDE/ATAPI controller by manually setting flags in the control software or switches in the hardware.
The limitations of current computer systems and operating system as described above reduce the productivity of computer users. A user using a Pnp compatible computer system and peripheral device who wishes to print a document and then fax the document but does not have any bays available for the fax machine must after printing shut down the computer system, remove a peripheral device from one of the bays, insert the fax/modem peripheral device into that bay, reinitialize the computer, call up the document, and proceed to transmit the document using the fax/modem peripheral. This operation is exceedingly inconvenient.
One prior art apparatus and method that overcomes the inherent limitations of Plug and Play systems is the “request/acknowledge hot swap” system. A computer system that supports the request/acknowledge hot swap scheme permits the installation and removal of peripheral devices after system power on and enumeration by the operating system. The computer user informs the operating system prior to performing the device insertion or removal, waits for the operating system acknowledgement which permits the operating system to partially power down the bus, and then performs the insertion or removal. The request/acknowledge scheme prevents corruption of data and protects the electrical integrity of the bus.
Request/acknowledge hot swap systems eliminate many of the disadvantages of Plug and Play systems but still cause user inconvenience due to the inherent delay caused by the request/acknowledge cycle. Another prior art apparatus and method, referred to as “surprise hot swapping” eliminates the need for the user to inform the operating system prior to performing the device insertion or removal. This method allows both power and data transfer interconnections between a computer bus and a newly installed device without requiring power to be removed from the bus. For example, computers and peripheral devices which adhere to the Personal Computer Memory Card International Association (PCMCIA) standard permit the hot insertion and hot removal of peripherals into the portable computers PCMCIA bays. The PCMCIA standard is presently in common use with notebook and laptop computers.
Like Plug and Play systems that require BIOS to implement functionality, a surprise hot swap system typically uses Basic Input Output Subsystem (BIOS) subroutines implemented by the computer system designer during system design to accommodate hot insertion and hot removal. BIOS subroutines continuously poll the PCMCIA peripheral bays to detect a peripheral device insertion or removal during system operation. Surprise hot swap systems are limited because the BIOS subroutines for such systems do not support hot insertion or hot removal for a wide array of bus standards such as IDE/ATAPI or PCI. Furthermore, BIOS hot insertion and hot removal systems are operating system dependent in that the operating system must recognize BIOS subroutine calls for hot insertion and removal and support requests for computer system resources from the subroutines. It would be advantageous to be able to surprise hot swap peripheral devices implemented on any bus standard in existing computer systems and across any operating system without having to modify the BIOS firmware and operating system that may be provided by companies other than the computer manufacturer.
For expanded capabilities, portable computers provide the option referred to as “hot docking” of coupling the portable computer to a docking station. In such scenarios, a fully operational (i.e., fully booted) portable computer may be inserted or “docked” to the docking station. The docking stations typically include a separate internal bus and associated bus co
Sakarda Premanand
Varma Sreedhar
Hewlett--Packard Development Company, L.P.
King Justin
Ray Gopal C.
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