Computer graphics processing and selective visual display system – Display driving control circuitry – Controlling the condition of display elements
Reexamination Certificate
1999-05-05
2001-04-24
Bayerl, Raymond J. (Department: 2773)
Computer graphics processing and selective visual display system
Display driving control circuitry
Controlling the condition of display elements
C345S215000, C709S241000, C709S241000, C709S201000
Reexamination Certificate
active
06222529
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of personal computer operating systems. In particular the present invention discloses methods for providing multiple individual user sessions that are controlled with remote hardware on an operating system designed only to support a single user.
BACKGROUND OF THE INVENTION
The currently available personal computer systems are equipped with large memory systems and high-speed processing power that was unavailable just a few years ago. The large memory and improved processing power has mostly been put to use in Graphical User Interfaces (GUI) implemented by windowing operating systems such as Microsoft's Windows and Apple Computer's MacOS. The graphical user interfaces simplify the operation of the personal computer system such that many people now use personal computer systems.
However, even with graphical user interface based operating systems, there is still plenty of processing power in most personal computer systems that is not being used. For example, when a user is reading a display screen, the personal computer system's processor is usually idle. Other times when the processor is idle include waiting for input/output devices to complete operations, times when the processor is waiting for an input from the user, times when the user is not using the personal computer system at all, and times when the user is waiting for information to be delivered across a slow network connection. In fact, the processors within most personal computer systems are idle for the majority of the time.
Since there is a large amount of unused processing power available in most personal computer systems, it would be desirable to be able to share this unused processing power with one or more other persons. However, most personal computers use the Windows 95 or Windows 98 operating systems that only provide input and output services for a single console. With the Windows 95 and Windows 98 operating systems, only one person can use the personal computer system. This is true despite the fact that the Windows 95 and Windows 98 operating systems are multi-tasking operating systems that can support several simultaneous application tasks. Thus, it would be desirable to find a way of sharing the processing power in a Windows 95 or Windows 98 based personal computer with other user at other consoles that are coupled to the personal computer system.
SUMMARY OF THE INVENTION
The present invention introduces a set of operating system extensions that allow a single user operating system to support multiple users. The operating system extensions of the present invention hook into an existing single user operating system such that additional users may be supported.
The present invention operates by creating multiple sets of operating system environments by copying a number of operating system variables that define the current operating system state. In a two user embodiment, a local personal computer console state is created for the user at the personal computer console and a remote console system state is created for a user at a remote console coupled to the personal computer system. A special virtual device driver then hooks into the operating system such that the special virtual device driver will be called before any thread switch. The special virtual device driver will load the proper operating system environment variables for the application that will be executed next.
The operating system extensions of the present invention also handle all input and output requests in a special manner. When the operating system extensions are initialized, a set of drivers is loaded for each user. The operating system extensions then hook all input and output operating system calls. Input and output operating system calls are handled by the operating system extensions such that all input and output requests from a user at the personal computer console are directed toward the normal set of personal computer device drivers. However, all input and output requests from a user at another console coupled to the personal computer system are directed toward a set of device drivers for that users console.
Other objects, features, and advantages of present invention will be apparent from the company drawings and from the following detailed description.
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Iyer Venkatesh
Mahannah Loren Ross
Ouatu-Lascar Mircea
Padmanabhan Murali
Rao Nagesh
Bayerl Raymond J.
Blakely , Sokoloff, Taylor & Zafman LLP
Nguyen Thomas T.
Shareware, Inc.
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