Abstract: A real-time, high uptime transaction processing system includes many user terminals communicating with service providers via a communications network. A defective logic board is replaced or a board providing system expansion is installed without powering down the system by providing external auxiliary voltages and a reset signal to the board to put it in a passive state while it is being plugged into or unplugged from its backplane connector. Also under computer control the system is made inactive for a short period of time.

Abstract: A communication data system is designed for resiliency by automatically replacing or bypassing defective units. The system includes a number of input/output terminals which are connected to MODEMs through a relay bank. The MODEMs send serial data to a serial I/O module which converts the serial data to bytes which it places on a VMEbus. A network processor sends the data from the VMEbus to a general purpose computer which places the data into the communications network. A general purpose computer or a back-up general purpose computer may detect a defective communication link and automatically switch to a back-up network computer, or cause a control module to switch the relay module to a spare MODEM and spare SIO. The control module may also generate a remote line test to the link between the MODEM and the terminal to determine if that link is defective.

Abstract: Data communication equipment, including relay modules and MODEMS, are mounted on etched back planes. Etched conductors transfer communication line signal pairs to the relay modules, from the relay modules to the MODEMS and from the MODEMS to an output connector. Ribbon cables plugged into the output connectors transfer the MODEM output signals to logic boards, which are plugged into an etched VME bus panel. CPU's plugged into the etched VME bush panel receive signals from and transfer signals to the etched VME bus.