System for controlling multiple port/multiple channel I/O configuration according to communication request initiation status

Claim 1

A computer system in which each of a plurality of requests for a communications connection between at least one of a plurality of selectable peripheral devices and a computer causes said at least one of said plurality of selectable peripheral devices to be selected for connection and connected through an I/O interface to one of a predetermined number of channel members connected to said computer, said channel members being for receiving and transmitting communications, said communications including data organized in control and data frames, said communications connection having a communications initiation status representing at least one of a plurality of available states of said communications across said communications connection said computer system comprising: a channel subsystem having said predetermined number of channel members therein, each said channel member in said channel subsystem including transfer means for transmitting said control and data frames to said at least one selected peripheral device and for receiving said control and data frames from said at least one selected peripheral device; a port subsystem forming part of said channel subsystem and having a given number of individual independent ports connected with said plurality of selectable peripheral devices, each said port in said port subsystem being for carrying said communications between said plurality of selectable peripheral devices and any one of said channel members in said channel subsystem, with said given number of ports being greater than said predetermined number of channel members; connection status means connected to each of said channel members in said channel subsystem for indicating which of said ports in said port subsystem is connected to said each channel member; access means connected to said connection means for allowing no more than one of said ports in said port subsystem to be connected to any said channel member in said channel subsystem at any time; and switch state means connected to each of said channel members in said channel subsystem for indicating at least one of said available states of said initiation status of said requested communications connection and for controlling said communications connection between said each channel member in said channel subsystem and said at least one selected peripheral device, said available states including a first simplex state wherein said communications connection is requested by one of said channel members but not yet made and a second simplex state wherein said communications connection is requested by one of said selectable peripheral devices but not yet made and a first duplex state wherein said requested communications connection is made and a second duplex state wherein said communications connection is simultaneously requested by said one channel member and said one selectable peripheral device.