Abstract: An ATM line card is provided wherein a microprocessor bus is selectively coupled to a memory bus during maintenance time intervals. This allows direct transfer of connection memory data to the microprocessor system of the line card and thus to the RAM of the system. After the transfer is accomplished the busses are decoupled again so that further maintenance work of the connection memory and the transferred data can be done independently. If the access to the connection memory is due to a destructive read operation the corresponding memory locations in the connection memory are reset simultaneous to the transfer of the data which are read out from the DMA of the microprocessor system to the RAM. This results in a dramatic reduction of the time required for maintenance of the ATM system.