Parallel port for connecting multiple devices and the method for controlling the same
First Claim
1. A method of controlling a parallel port for connecting multiple devices to a computer, comprising the steps of:
- storing a control status and a data status of a first device, which is one of the multiple devices and keeps on-line with said computer, when said computer is to switch on-line state from said first device to a second device (one of the multiple devices);
delivering an off-line code from said computer through a data bus to disconnect said first device from said computer and storing control signals of said first device;
delivering control signals of said second device through a control bus and an on-line code of said second device through said data bus, from said computer, to connect said second device to said computer and to drive said second device;
delivering said off-line code from said computer through said data bus to disconnect said second device from said computer and storing the control signals of said second device, when said computer is to switch the on-line state from said second device to said first device;
recovering the control status of said first device stored previously and delivering the on-line code of said first device to connect said first device to said computer; and
recovering the data status of said first device to return to the on-line state of said computer in connecting to said first device.
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Accused Products
Abstract
A method of controlling a parallel port for connecting multiple devices is disclosed. The method controls the connection between a computer and one of the peripheral devices by way of using the different on-line codes corresponding to the peripheral devices respectively. Further, a common off-line code is set and shared by all peripheral devices. When the off-line code is sent out, all peripheral devices are disconnected from the computer, and the control status of the previous on-line device is backed up for the use of recovering the previous on-line state. Furthermore, a parallel port for connecting multiple devices is also proposed to incorporate with the controlling method such that the computer can switch the on-line state between an on-line peripheral device and the other peripheral standby devices.
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Citations
11 Claims
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1. A method of controlling a parallel port for connecting multiple devices to a computer, comprising the steps of:
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storing a control status and a data status of a first device, which is one of the multiple devices and keeps on-line with said computer, when said computer is to switch on-line state from said first device to a second device (one of the multiple devices); delivering an off-line code from said computer through a data bus to disconnect said first device from said computer and storing control signals of said first device; delivering control signals of said second device through a control bus and an on-line code of said second device through said data bus, from said computer, to connect said second device to said computer and to drive said second device; delivering said off-line code from said computer through said data bus to disconnect said second device from said computer and storing the control signals of said second device, when said computer is to switch the on-line state from said second device to said first device; recovering the control status of said first device stored previously and delivering the on-line code of said first device to connect said first device to said computer; and recovering the data status of said first device to return to the on-line state of said computer in connecting to said first device. - View Dependent Claims (2, 3)
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4. A parallel port for connecting multiple devices to a computer, comprising:
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a parallel port connector for connecting said computer; a plurality of control units connected to said parallel port connector in parallel, wherein each control unit is connected with a peripheral device, and comprises; a recognition device, an input of which is coupled to a data bus of said parallel port connector, controlling an on-line state and an off-line state between said computer and said peripheral device by means of receiving various identification codes on said data bus; a latch device wherein an input of said latch device is coupled to a control bus of said parallel port connector, and an output of said latch device is coupled to a control input of said peripheral device, and control signals for connecting said peripheral device are transmitted to said peripheral device or latched according to output signals from said recognition device coupled to the control input of said latch device; and a selecting device receiving the output signals from said recognition device to determine a connection between a status bus of said parallel port connector and a status output terminal of said peripheral device. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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Specification