US 4,794,520 A · Interface system for computer port sharing of multiple devices

Abstract

Expanded utilization by several different devices from a single output port such as the RS-232 port of a personal computer is effected by connecting the data line of the serial output port in parallel to several different solid state switches each of which is capable of routing the data information to one or the other of two utilization devices. Selection of a particular switch is effected through micro-controllers which are connected to the control line of the serial output port. Unique address messages are supplied to the host computer at a baud rate which is high compared to the normal rate of change of signals on the control lines and these addressing signals are uniquely decoded by the micro-controllers to select a specific micro-controller, then to select a specific output of that micro-controller activating a solid state switch to select the utilization device to communicate with the computer over the data line.

Claims29

Dependent claims

A multiple device addressing and routing system for selectively supplying data from a single output port of a computer to one of a plurality of utilization devices, wherein such output port has at least a data line and a control line on which encoded selection signals are applied, said system including in combination:

controller means coupled to the control line of said output port, said controller means having at least one output line and having decoding means therein responsive to encoded selection signals appearing on such control line for producing one of two output signals on said output line thereof as determined by such encoded selection signals;
switch means having first and second states of operation, having a control input coupled to said output line and having first and second outputs, said switch means coupled to the data line of said output port for supplying signals appearing on the data line of said output port to a selected one of said first and second outputs of said switch means corresponding to said first and second states of operation thereof respectively in response to the output signal on said output line;
and
means for coupling first and second utilization devices to said first and second outputs of said switch means.

1 more element

A multiple device addressing and routing system for selectively supplying data from a single output port of a computer to one of a plurality of utilization devices wherein such output port has at least a data line, and a control line on which encoded selection signals are applied, said system including in combination:

a plurality of control means coupled in parallel to the control line of said output port, each of said control means having at least one output line and having decoding means therein for activating a selected one of said control means in response to uniquely encoded selection signals identifying each specific control means in response to encoded selection signals appearing on such control line, for producing one of two output signals on the output line thereof as determined at least in part by such encoded selection signals;
first and second switch means having for each of said control means with each of said switch means having a control input connected with the output of a corresponding control means, each of said switch means having first and second outputs, said first switch means coupled to the data line of said serial output port for supplying signals appearing on said data line to a selected one of said first and second outputs of said switch means corresponding to the operation thereof, and said second switch means coupled to the control line of said serial output port for supplying control signals appearing on said control line to a selected one of said first and second outputs of said second switch means corresponding to the operation thereof, the operation of said first and second switch means being established by the signals on the control input thereof;
means for coupling the data inputs of first and second utilization devices to the first and second outputs, respectively, of said first switch means;
and
means for coupling the control inputs of first and second utilization devices to the first and second outputs respectively of said second switch means.

2 more elements

Dependencies are inferred from the claim text.

Interface system for computer port sharing of multiple devices

Life of this patent

Interface system for computer port sharing of multiple devices

Life of this patent

Abstract

Claims29