Data processing: generic control systems or specific application – Generic control system – apparatus or process – Supervisory control
Reexamination Certificate
1999-03-15
2001-04-24
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Supervisory control
C714S048000
Reexamination Certificate
active
06223089
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A “MICROFICHE APPENDIX”
Not Applicable
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates in general to a method and apparatus for controlling computers remotely. The invention more particularly relates to a computer being controlled remotely by an operator terminal via a high speed fiber-optic transmission line.
2. Background Art
In many applications, data security for computers is of paramount importance. For example, computers used on factory floors, hospitals, financial institutions, public venues, refineries and other such applications oftentimes present issues relating to the security of the data being processed. Also, the environment may not be suitable for the use of the computers where it may be difficult or impossible to maintain a proper operating environment relative to temperature and humidity.
Therefore, it has been proposed to have the computer disposed in a safe and controlled environment, and have one or more operator terminals located remotely from the computer at a position where the user can enter and receive information interactively with the computer. In this regard, the computer can then be secured in a safe, air-conditioned location away from the environment where the operator terminal can still communicate with the computer.
There can be many applications where the operator terminal must be located at a great distance from the computer. For example, it may be desirable to have the operator terminal located at a position many kilometers apart from the computer. At such great distances, it becomes important to have a high speed transmission link such as a fiber-optic transmission line interconnect one or more of the operator terminals with the remotely located computer. High speed transmission links require a very stable (low jitter or phase noise reference clock.) As a result, such a system can be inherently unstable in its data transfer over the fiber-optic transmission line. More specifically, for example, if a 40 bit data word is used, an additional eight bits of link management and protocol information must be added to each data word, for a total of 48 bits. If the system is to operate at a 32.5 MHz clock speed, then the system must operate at 1.569 GHz (32.5 MHz times 48 bits). The period for such a rate would then be 0.637 Nano seconds. If the phase noise or jitter is equal to about one Nano seconds, the period for transmitting the information would actually be less than the period for the jitter, thereby resulting in a totally unacceptable and inherently unstable system.
Therefore, in order to have a long distance remotely controllable computer system over high speed fiber-optic transmission lines, it would be necessary to have a method and apparatus which would be able to transmit information in a highly stable and reliable manner.
Additionally, with such a remotely controllable system, it is also important that the system be highly reliable to maintain the integrity of the data. In this regard, special consideration must be made to ensure that the fiber-optic connection is “hot-pluggable.” This means that the fiber-optic connection should be able to be disconnected from a failed or failing computer and then connected to a back-up computer without the need for rebooting either computer. This feature would also be useful when upgrading software and/or hardware. Similarly, it would be desirable to disconnect an operator terminal, or connect one to the transmission line without disrupting the operation of the computer. Additionally, especially where long distances are encountered, it would be desirable to prevent the computer from requiring rebooting should the fiber-optic transmission line be disrupted or severed inadvertently.
Thus, it would be highly desirable to have such a new and improved method and apparatus for controlling a computer remotely, even at long distances, while enabling either the computer or the operator terminal to be disconnected from the fiber-optic transmission line, or the transmission line becoming inadvertently disabled, without interrupting or otherwise disturbing the computer in a “hot pluggable” manner.
SUMMARY OF THE INVENTION
The above and further objects of the present invention are realized by providing a new and improved method and apparatus for controlling remotely a computer, wherein the computer can continue to operate efficiently and effectively even in adverse conditions and where the computer and one or more of its operator terminals are spaced apart physically at great distances.
Another object of the present invention is to provide such a new and improved method and apparatus for controlling remotely a computer, wherein the system apparatus a fiber-optic transmission line and yet is able to communicate between the computer and a remotely located operator terminal by transmitting stable data.
A further object of the present invention is to provide such a new and improved method and apparatus for controlling remotely a computer, wherein either the computer or the operator terminal can be disconnected from the fiber-optic transmission line, or the line itself be damaged or otherwise disabled inadvertently, without substantially interrupting the operation of the computer.
Briefly, the above and further objects of the present invention are realized by providing such a new and improved method and apparatus for controlling remotely a computer by an operator terminal over a high speed transmission line, such as a fiber-optic transmission line, wherein the data is able to be transmitted in a highly stable manner. Also, such method and apparatus should enable the computer to continue functioning without any substantial interruption, even when the computer or the operator terminal is disconnected from the fiber-optic transmission line, or the line itself becomes damaged or severed inadvertently.
The inventive method and apparatus for enabling an operator terminal to control remotely a computer system enables data to be transmitted over long distances in a highly stable manner by deleting a message if a mismatch occurs between the data and error checking information contained in the received data. The computer is then subsequently returned to its last valid state to prevent the system from inadvertently becoming disrupted either by the terminal or the computer being disconnected from the transmission line during an idle condition of the system, or by spurious data containing messages being received, such as where the transmission line becomes disrupted inadvertently. A voltage controlled oscillator generates a stable reference clock signal, and a phase detector responds to the stable reference clock signal and to the pixel clock signal for, in turn, controlling the oscillator. Such a stable reference clock signal enables a high volume of information to be transmitted over the high speed transmission line, without being adversely affected by phase noise or jitter.
One advantage of the present inventive system is that the fiber-optic transmission line link is transparent to the operating system of the computer. The computers operating system sees the transmission line system as a simple flat panel video controller and two standard serial ports of the operator terminal. The computer does not “know,” nor does it need to know, that the display and serial port terminations may be several kilometers away from the computer. Thus, the user can install conventional software drivers that typically are supplied with the operating system.
Video controllers that are designed to drive conventional flat panel displays must use firmware (video BIOS) which is specific for the timing and data-format requirements of the target display. A non-volatile memory device, such as an EPROM, is conventionally used to store this information. Typically, the EPROM has to be physically replaced with one containing the appropriate configuration information when a different displa
Cabrera Zoila
Foley & Lardner
Grant William
Kleinke Bernard L.
Raylar Design, Inc.
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