High performance cascadable simplex switch

A data communications system comprising:

• a first simplex serial crossbar switch having a plurality of first I/O ports of which (i) at least one of said plurality of first I/O ports is connected to a communications subsystem which passes data and control messages to other communications subsystems via said first simplex serial crossbar switch, and (ii) at ;least one of said plurality of first I/O ports is connected to a corresponding one of a plurality of second I/O ports on a second simplex serial crossbar switch, said second simplex serial crossbar switch also provided with at least one second I/O port which is connected to a communications subsystem which passes data and control messages to other communications subsystems via the second simplex serial crossbar switch;
• each of said plurality of first I/O ports on said first serial simplex switch having programmable latches for alternatively programming each of said first I/O ports to be connected to either (i) a communications subsystem, wherein a single first I/O port is connected to a single subsystem and said single first I/O port manages both data and control messages sent to and from the connected single subsystem, or (ii) one of said plurality of second I/O ports on said second simplex switch, wherein a pair of first I/O ports on said first switch are connected to a pair of similarly configured second I/O ports on said second simplex switch, and wherein one of said pair of first I/O ports manages the transfer of data and the other of said pair of first I/O ports manages the transfer of control messages.