The EDT HRC is a mezzanine board that pairs with a PCI/e main board for high speed data transfer. It supports both E4 or STS3 electrical signals and OC3/STM1 optical signals in numerous combinations. The four connector slots all support an electrical BNC 75-W CMI coaxial interface, or an optical LC 1310 nm NRZ single-mode transceiver. The BNCs can be set by programmable control as either input or output. Bi-directional operation is possible on two channels.