half and full duplex modem

 Modems can be classified based on their directional capacity as either "full-duplex" or "half-duplex."

Full-duplex modems are capable of transmitting and receiving data simultaneously. This means that data can be sent and received at the same time, allowing for a more efficient and faster communication. Examples of full-duplex modems include cable modems and fiber-optic modems.

Half-duplex modems, on the other hand, can only transmit or receive data at a given time. This means that data can only be sent or received one direction at a time, and the direction must be switched manually. Examples of half-duplex modems include dial-up modems and some older DSL modems.

It's important to note that full-duplex modems tend to be faster and more efficient than half-duplex modems, as they can send and receive data simultaneously. However, half-duplex modems are still in use in some areas where full-duplex modems are not yet available.