The carrier card features two mezzanine slots with associated FPGAs (Xilinx Spartan-3A 1400), a Gigabit Ethernet PHY (Marvell 88E1111), a USB 2.0 controller, and an RS-485 controller for serial connections. Board-to-board communication is implemented using 16 single-ended wires between the FPGAs, which can be combined to 8 differential signal lines using the LVDS standard [6]. Global event timing can be realized by using a central clock that is distributed to all carrier cards of the system. On each carrier card a LMK03000 clock conditioner chip is used to create low-jitter clock signals that clock the FPGAs and mezzanine cards. The FPGAs, which run at 120 MHz, generate initial, low-resolution timestamps with a precision of 8.33 ns. A reference signal applied to the 9th DRS4 channel is intended to derive a second, high-resolution timestamp with nanoseconds precision. This timing performance of the system has not yet been demonstrated, however.