Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral adapting
Reexamination Certificate
1997-10-27
2001-04-03
Auve, Glenn A. (Department: 2781)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral adapting
C710S108000
Reexamination Certificate
active
06212584
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to communications system generally, and more particularly to a time-division multiple-access communications protocol for use in a multi-user computer system.
2. Description of the Prior Art
A personal computer typically contains a processor, memory, storage devices, printer, etc., and is ordinarily used in a single-user environment. A personal computer may also be connected to a computer network to share common resources such as mass storage devices, printers, database, etc, with other computer systems. However, the cost of setting up and maintaining a computer network is ordinarily beyond that which a small office or a family can include within their budget. A solution is to provide an inexpensive multi-user computer system for use in a small office or home.
A multi-user computer system may accommodate the need of a networked computer system in a small office or a home. A multi-user computer system typically contains a base unit and at least one front-end unit for user interface. The base unit usually contains the typical components of a computer system, such as a processor, memory devices, and mass storage devices. It also contains input devices, such as a keyboard or a mouse, and output devices such as a monitor and a printer. The front-end units may include a display monitor, a keyboard, and a mouse. The multi-user computer system described above may substitute the network computer system for use in a family or small office, because such a multi-user system may be used by multiple users simultaneously. In such a multi-user system it is essential that the processor possess a strong processing power to accommodate the operations requested by the base unit and the front-end unit.
The personal computer industry has experienced tremendous growth in the last decade. Personal Computers are now both affordable and ubiquitous. Storage devices are more compact in size yet have a much higher storage capacity. Processors have much higher processing power than their typical usage requires and display devices are capable of displaying color video graphics instead of merely monochrome text. It is now possible to apply the multi-user concept in a personal computer system. This can be accomplished by adding to a personal computer front-end units that utilize the processor's processing power and the storage devices' storing capacity.
One of the difficulties in providing such a multi-user computer system is in transmitting the video signals from the base unit to the front-end unit. In an IBM Personal Computer compatible system, 15 signals are required to drive a color display on a color video monitor. The 15 signals include Red, Green, and Blue (RGB) colors and their respective return signals, and horizontal synchronous (H-Sync), vertical synchronous (V-Sync) and ground signals. A keyboard requires five signal lines, and a mouse requires 9 other lines. Hence, to support a front-end system that utilizes a color video display, a keyboard, and a mouse for a typical Windows environment, a minimum of 29 signal lines is required. One may use a cable to transmit all of the relevant signals from the base unit to the front-end unit. However, the RGB signals are transmitted in analog format. They need to be shielded to prevent them from interfering with other devices within its proximity. Analog signals that drive the analog monitor can only be transmitted within [its] their proximity. Hence, this limits the front-end unit's distance from the base unit.
Moreover, most of the systems utilize a cable of only a few feet in length for transmitting the video signals to the monitor. This limitation substantially restricts the location of the auxiliary unit to be within the proximity of the processor. It is desirable that auxiliary unit be located in a different room than the base unit. Hence, it is desirable that the video signals can be transmitted for a longer distance to a remote location.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a multi-user computer system with a shared hardware and software, yet able to provide the user with the state-of-the-art color video graphics display in a Windows operating environment.
It is another object of the present invention to provide a simple alternative in transmitting a plurality of signals via a single transmission line. In this arrangement multiple signals may be transmitted without using multiple signal lines. The single transmission line is used by partitioning the access to the line in reference to time so that multiple sources may access the same transmission line in a different time domain.
In a specific embodiment of the present invention, a multi-user computer system using a communications protocol in transmitting data between a plurality of user interface units is described. The system includes a base unit, which has a bus, a processor coupled to the bus, a display device coupled to the bus, an input device also coupled to the bus, and an interface controller coupled to the bus, wherein said processor controls the operation of the base unit and processes data entered into the base unit and operates to generate output data to be displayed on the display device. The system also includes an auxiliary unit, which has a protocol interface controller, a second display device coupled to the protocol interface controller, a second input device coupled to the protocol interface controller, wherein the protocol interface controller controls the operation of the auxiliary unit and interfaces with the base unit in accordance with a predetermined communications protocol. The system further includes a communications cable that provides a communication pathway between the base unit and the auxiliary unit, which has a plurality of unshielded twisted-pair conductors coupled to the interface controller and the protocol interface controller for transmitting signals between said base unit and said auxiliary unit, wherein the signals to be transmitted include data and red-green-blue (RGB) video signals, said base unit receives input data from said auxiliary unit via said communications cable and operates to generate output data to be displayed on the second display device of said auxiliary unit and transmits the output data via said communications in accordance with the predetermined communications protocol.
It is an advantage of the present invention that it provides a multi-user computer environment with a shared hardware and software, and still able to provide the user with the state of the art color video graphics display in a Windows operating environment.
It is another advantage of the present invention that it provides a simple alternative to the transmission of a plurality of signals via a single transmission line to eliminate the need of connecting multiple signal lines in a communications cable by dividing the time to allow multiple sources to access the same transmission line.
The foregoing and other objects, features and advantages of the present invention will be apparent to those skilled in the art after having read the following detailed description of the preferred embodiments, which make reference to the several figures of the drawing.
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Newton's Telecom Dictionary, pp. 516-517, Jul. 1996.
Auve Glenn A.
Chou Chien-Wei (Chris)
Maxspeed Corporation
Oppenheimer Wolff & Donnelly LLP
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