With firmware option CSR, U5303A 12-bit PCIe Digitizer enables engineers to perform acquisition and readout simultaneously and in continuous way. CB0 application option, implementing real-time digitizer data recorder, provides command line interface and data viewer. Recording performance up to 1 GBps is ensured in specific qualified system. Adding real-time digital down-converter functionality, CB1 option ensures recording performance up to 180 MHz.